%0 journal article %@ 2077-1312 %A Mai, H., Wang, D., Chen, H., Qiu, C., Xu, H., Shang, X., Zhang, W. %D 2024 %J Journal of Marine Science and Engineering %N 5 %P 700 %R doi:10.3390/jmse12050700 %T Mid-deep Circulation in the Western South China Sea and the Impacts of the Central Depression Belt and Complex Topography %U https://doi.org/10.3390/jmse12050700 5 %X As a key component of meridional overturning circulation, mid-deep circulation plays a crucial role in the vertical and meridional distribution of heat. However, due to a lack of observation data, current knowledge of the dynamics of mid-deep circulation currents moving through basin boundaries and complicated seabed topographies is severely limited. In this study, we combined oceanic observation data, bathymetric data, and numerical modeling of the northwest continental margin of the South China Sea to investigate (i) the main features of mid-deep circulation currents traveling through the central depression belt and (ii) how atmospheric-forcing (winds) mesoscale oceanic processes such as eddies and current–topography interactions modulate the mid-deep circulation patterns. Comprehensive results suggest that the convergence of different water masses and current–topography interactions take primary responsibility for the generation of instability and enhanced mixing within the central depression belt. By contrast, winds and mesoscale eddies have limited influence on the development of local circulation patterns at mid-deep depths (>400 m). This study emphasizes that the intensification and bifurcation of mid-deep circulation; specifically, those induced by a large depression belt morphology determine the local material cycle (temperature, salinity, etc.) and energy distribution. These findings provide insights for a better understanding of mid-deep circulation structures on the western boundary of ocean basins such as the South China Sea. %0 journal article %@ 2941-0371 %A Bormann, H., Berkenbrink, C., Karrasch, L., Massmann, G., Ratter, B., Wessels, A., Weisse, R. %D 2024 %J Notfallvorsorge %P 17-25 %T Wasser an den Küsten Ostfrieslands (WAKOS): maßgeschneiderte Klimaservices für die Anpassung %U %X Wasser und damit verbundene Naturgefahren stellen die nordwestdeutsche Küstenregion seit jeher vor große Herausforderungen, sowohl kurzfristig für das Risikomanagement, als auch langfristig bei der Anpassung an den Klimawandel. Gemeinsam mit Praxispartnern in der Region untersucht das Projekt WAKOS, wie die Küstenregion gegenüber Ereignisbündeln, z. B. dem gleichzeitigen Auftreten von Sturmfluten und Starkregen, und vor den Folgen des Klimawandels nachhaltig geschützt werden kann. %0 journal article %@ 0301-4797 %A Stelzenmüller, V., Rehren, J., Örey, S., Lemmen, C., Krishna, S., Hasenbein, M., Püts, M., Probst, W.N., Diekmann, R., Scheffran, J., Bos, O.G., Wirtz, K. %D 2024 %J Journal of Environmental Management %P 119507 %R doi:10.1016/j.jenvman.2023.119507 %T Framing future trajectories of human activities in the German North Sea to inform cumulative effects assessments and marine spatial planning %U https://doi.org/10.1016/j.jenvman.2023.119507 %X The global industrialization of seascapes and climate change leads to an increased risk of severe impacts on marine ecosystem functioning. While broad scale spatio-temporal assessments of human pressures on marine ecosystems become more available, future trajectories of human activities at regional and local scales remain often speculative. Here we introduce a stepwise process to integrate bottom-up and expert-driven approaches for scenario development to inform cumulative effects assessments and related marine spatial planning (MSP). Following this guidance, we developed optimistic, realistic, and pessimistic scenarios for major human pressures in the German North Sea such as bottom trawling, offshore wind, nutrient discharge, and aggregate extraction. The forecasts comprise quantitative estimates in relation to spatial footprint, intensity, and technological advancements of those pressures for the years 2030 and 2060. Using network analyses, we assessed interactions of the current and future trajectories of pressures thereby accounting for climate change and the growing need for marine conservation. Our results show that future scenarios of spatial distributions could be developed for activities that are spatially refined and included in the current MSP process. Further our detailed analyses of interdependencies of development components revealed that forecasts regarding specific targets and intensities of human activities depend also strongly on future technological advances. For fisheries and nutrient discharge estimates were less certain due to critical socio-ecological interactions in the marine and terrestrial realm. Overall, our approach unraveled such trade-offs and sources of uncertainties. Yet, our quantitative predictive scenarios were built under a sustainability narrative on a profound knowledge of interactions with other sectors and components in and outside the management boundaries. We advocate that they enable a better preparedness for future changes of cumulative pressure on marine ecosystems. %0 journal article %@ 1561-8633 %A Meyer, E.M.I., Gaslikova, L. %D 2024 %J Natural Hazards and Earth System Sciences %N 2 %P 481-499 %R doi:10.5194/nhess-24-481-2024 %T Investigation of historical severe storms and storm tides in the German Bight with century reanalysis data %U https://doi.org/10.5194/nhess-24-481-2024 2 %X Century reanalysis models offer a possibility to investigate extreme events and gain further insights into their impact through numerical experiments. This paper is a comprehensive summary of historical hazardous storm tides in the German Bight (southern North Sea) with the aim of comparing and evaluating the potential of different century reanalysis data to be used for the reconstruction of extreme water levels. The composite analysis of historical water level extremes, underlying atmospheric situations and their uncertainties may further support decision-making on coastal protection and risk assessment. The analysis is done based on the results of the regional hydrodynamic model simulations forced by atmospheric century reanalysis data, e.g. 20th Century Reanalysis Project (20CR) ensembles, ERA5 and UERRA–HARMONIE. The eight selected historical storms lead either to the highest storm tide extremes for at least one of three locations around the German Bight or to extreme storm surge events during low tide. In general, extreme storm tides could be reproduced, and some individual ensemble members are suitable for the reconstruction of respective storm tides. However, the highest observed water level in the German Bight could not be simulated with any considered forcing. The particular weather situations with corresponding storm tracks are analysed to better understand their different impact on the peak storm tides, their variability and their predictability. Storms with more northerly tracks generally show less variability in wind speed and a better agreement with the observed extreme water levels for the German Bight. The impact of two severe historical storms that peaked at low tide is investigated with shifted tides. For Husum in the eastern German Bight this results in a substantial increase in the peak water levels reaching a historical maximum. %0 journal article %@ 1616-7341 %A Pein, J., Staneva, J. %D 2024 %J Ocean Dynamics %P 335–354 %R doi:10.1007/s10236-024-01607-w %T Eutrophication hotspots, nitrogen fluxes and climate impacts in estuarine ecosystems: a model study of the Odra estuary system %U https://doi.org/10.1007/s10236-024-01607-w %X The Odra estuary in the southern Baltic Sea comprises the Odra (Szczecin) Lagoon, the Pomeranian Bay and a number of other shallow water areas and channels. Known for its abundance of fish, eutrophication in the Odra Lagoon is a pressing issue for science and environmental management representing a global problem: What determines the seasonal variability of nitrogen and nitrogen turnover in shallow water areas, and how does seasonal variability change due to climatic changes such as warming and sea level rise? How do such changes affect nutrient exports to the regional ocean? This study employs a high-resolution unstructured model system to investigate physical-biogeochemical interactions, nitrogen turnover, and conditions leading to nitrogen export to the Baltic Sea within the Odra estuary. The research comprises hindcast and a climatic experiment with modified water level and temperature inputs. The model reproduces the thermohaline dynamics of brackish shallow water areas, phytoplankton blooms and the variability of inorganic nitrogen. The simulations identify the dynamic partitioning of the Odra Lagoon into the highly eutrophic, lake-like Small Lagoon and more frequently flushed, zooplankton-rich Great Lagoon. Although the two years of the hindcast simulation feature very different boundary conditions in terms of river forcing, comparable patterns of seasonal nitrogen export emerge. In a climate change experiment with increased sea levels and global temperatures, the system appears sensitive, but remains stable with regard to nutrient transport and is therefore predictable. The climate change experiment reveals enhanced primary producer biomass concentrations, suggesting heightened eutrophication. While in the shallow waters of Odra Lagoon oxygen concentration remains relatively stable, oxygen depletion intensifies as the lagoon outflows enter the Pomeranian Bay. This phenomenon is linked to increased denitrification within the stratified Odra plume. Deeper, meandering channels, such as Swina, demonstrate resilience to oxygen reduction, influenced by sea level rise and enhanced currents. Based on the temporal-spatial high-resolution coupled, validated simulations, it is possible to develop tailor-made management solutions without having to run expensive and complicated observation campaigns in the shallow waters with complex topography. %0 journal article %@ 2045-2322 %A Akhtar, N., Geyer, B., Schrum, C. %D 2024 %J Scientific Reports %P 6608 %R doi:10.1038/s41598-024-56731-w %T Larger wind turbines as a solution to reduce environmental impacts %U https://doi.org/10.1038/s41598-024-56731-w %X The EU aims for carbon neutrality by 2050, focusing on offshore wind energy. Investments in North Sea wind farms, with optimal wind resources, play a crucial role. We employed a high-resolution regional climate model, which incorporates a wind farm parametrization, to investigate and address potential mitigating impacts of large wind farms on power generation and air-sea fluxes. Specifically, we examined the effects of replacing 5 MW turbines with larger 15 MW turbines while maintaining total capacity. Our study found that substituting 15 MW turbines increases the capacity factor by 2–3%, enhancing efficiency. However, these turbines exhibit a slightly smaller impact on 10 m wind speed (1.2–1.5%) and near-surface kinetic energy (0.1–0.2%), leading to reduced effects on sea surface heat fluxes compared to 5 MW turbines. This was confirmed by a stronger reduction in net heat flux of about 0.6–1.3% in simulations with 5 MW compared to 15 MW wind turbines. Air-sea fluxes influence ocean dynamics and marine ecosystems; therefore, minimizing these impacts is crucial. Overall, deploying 15 MW turbines in offshore wind farms may offer advantages for ocean dynamics and marine ecosystems, supporting the EU's carbon–neutral objectives. %0 journal article %@ 0308-597X %A Gee, K., Arndt, P., Dahmen, M., Geitel, N.K., Hunke, A., Käppeler, B., Plug, D., Scheffler, U., Trümpler, K. %D 2024 %J Marine Policy %P 106006 %R doi:10.1016/j.marpol.2024.106006 %T A new maritime spatial plan for the German EEZ: Navigating multiple aspirations and spatial developments %U https://doi.org/10.1016/j.marpol.2024.106006 %X A new maritime spatial plan for the German EEZ has come into force in 2021, replacing the first plans for the North Sea and Baltic Sea dating back to 2009. This paper discusses key changes in the new plan, highlighting how it has adapted to changing circumstances and demands within the existing framework of spatial planning legislation. While the regulatory instruments available to MSP have remained unchanged, we find that the understanding of MSP has become more complex, not least in response to the EU MSPD. More uses and activities have been allocated priority and reservation areas and there is innovation in the use of overlapping, temporary and conditional priority areas. Changes are also apparent in the planning process which has become closely interlinked with the SEA process. Nonetheless, we also highlight challenges MSP in the EEZ still needs to navigate. These relate to the rapid expansion of offshore wind farming, the inclusion of climate change in MSP, application of the ecosystem approach, as well as transparency in the final stages of the MSP process. %0 journal article %@ 2352-4855 %A Hosseini, S.T., Siadatmousavi, S.M., Stanev, E., Pein, J., Schrum, C. %D 2024 %J Regional Studies in Marine Science %P 103525 %R doi:10.1016/j.rsma.2024.103525 %T Transitions Between Different Estuarine States in a Low-inflow Estuary of Arid Coasts (Mond Estuary, Persian Gulf) with a Focus on Freshwater Lenses %U https://doi.org/10.1016/j.rsma.2024.103525 %X This study shows that the Mond Estuary, Persian Gulf experiences notable time-dependent longitudinal salinity variations. Monthly-seasonal variability in salinity changes from a positive estuarine system in wintertime to inverse and salt-plug estuaries during summertime. A highly unsteady state (time scale of hours-days) occurs in the wintertime named the freshwater lens estuary (FLE), in which a low-salinity water mass (lens) is confined by both marine and riverine saltwater sources. Here, FLE dynamics is investigated using realistic and idealized numerical models and two 25-hour data sets collected immediately before a hypersaline runoff (weak FLE condition) and during another one (strong FLE condition). The Péclet Number (Pe) reveals a much stronger advective transports than diffusive one (Pe > 5.7) throughout the estuary. An exception from this behavior (stronger mixing with Pe = 0.8) is observed at the estuary downstream, where a significant amount of freshwater mixes with seawater during the weak FLE conditions. Also, the minimum hypersaline runoff of ∼400 m3/s estimated by the numerical model can dampen tidal waves at the head of the estuary. In an idealized basin, the model shows that FLE longitudinal flows form two cells of positive estuarine circulation separated by a maximum mixing zone (the potential energy anomaly <0.75 J/m3). In the Mond Estuary, a sea-level rise of 20 cm increases salinity in the FLE state and the positive estuary during winter. Conversely, it decreases salinity in the inverse and salt-plug estuaries in summer. %0 journal article %@ 1991-959X %A Klockmann, M., von Toussain, U., Zorita, E. %D 2024 %J Geoscientific Model Development %N 4 %P 1765–1787 %R doi:10.5194/gmd-17-1765-2024 %T Towards variance-conserving reconstructions of climate indices with Gaussian Process Regression in an embedding space %U https://doi.org/10.5194/gmd-17-1765-2024 4 %X We present a new framework for the reconstruction of climate indices based on proxy data such as tree rings. The framework is based on the supervised learning method Gaussian Process Regression (GPR) and aims at preserving the amplitude of past climate variability. It can adequately handle noise-contaminated proxies and variable proxy availability over time. To this end, the GPR is formulated in a modified input space, termed here embedding space. We test the new framework for the reconstruction of the Atlantic multi-decadal variability (AMV) in a controlled environment with pseudo-proxies derived from coupled climate-model simulations. In this test environment, the GPR outperforms benchmark reconstructions based on multi-linear principal component regression. On AMV-relevant timescales, i.e. multi-decadal, the GPR is able to reconstruct the true amplitude of variability even if the proxies contain a realistic non-climatic noise signal and become sparser back in time. Thus, we conclude that the embedded GPR framework is a highly promising tool for climate-index reconstructions. %0 journal article %@ 0078-3234 %A Omstedt, A., von Storch, H. %D 2024 %J Oceanologia %N 1 %P 1-8 %R doi:10.1016/j.oceano.2023.06.001 %T The BALTEX/Baltic Earth program: Excursions and returns %U https://doi.org/10.1016/j.oceano.2023.06.001 1 %X The Baltic Sea Experiment (BALTEX) started in 1993 as part of the Global Energy and Water Cycle Experiment (GEWEX). It was later organized into three programs: BALTEX I, BALTEX II, and Baltic Earth. Here, we examine in a brief overview the overall BALTEX achievements, including program goals, risks encountered during the research journey, and knowledge development when finalizing the programs. During three decades of climate and environmental studies of the Baltic Basin within the BALTEX/Baltic Earth programs, significant steps have been taken towards improved scientifically constructed knowledge and efforts to disseminate this knowledge to neighboring sciences and the public. These programs have illustrated the need to actively navigate the European research arena while remaining an independent science network. The well-organized International Baltic Earth Secretariat and many dedicated scientists made the research excursions safe and successful. The learning process relates to improved knowledge of the dynamics of the atmosphere–ocean–land climate system in the Baltic Sea region, the cycling of carbon and other substances, the region's anthropogenic climate and environmental changes, and how global warming and regional human activities can be detected outside natural variability. %0 journal article %@ %A Mathis, M., Lacroix, F., Hagemann, S., Nielsen, D.M., Ilyina, T., Schrum, C. %D 2024 %J Nature Climate Change %P 373–379 %R doi:10.1038/s41558-024-01956-w %T Enhanced CO2 uptake of the coastal ocean is dominated by biological carbon fixation %U https://doi.org/10.1038/s41558-024-01956-w %X Observational reconstructions indicate a contemporary increase in coastal ocean CO2 uptake. However, the mechanisms and their relative importance in driving this globally intensifying absorption remain unclear. Here we integrate coastal carbon dynamics in a global model via regional grid refinement and enhanced process representation. We find that the increasing coastal CO2 sink is primarily driven by biological responses to climate-induced changes in circulation (36%) and increasing riverine nutrient loads (23%), together exceeding the ocean CO2 solubility pump (41%). The riverine impact is mediated by enhanced export of organic carbon across the shelf break, thereby adding to the carbon enrichment of the open ocean. The contribution of biological carbon fixation increases as the seawater capacity to hold CO2 decreases under continuous climate change and ocean acidification. Our seamless coastal ocean integration advances carbon cycle model realism, which is relevant for addressing impacts of climate change mitigation efforts. %0 journal article %@ 1561-8633 %A Goulart, H.M.D, Benito Lazaro, I., van Garderen, L., van der Wiel, K., Le Bars, D., Koks, E., van den Hurk, B. %D 2024 %J Natural Hazards and Earth System Sciences %N 1 %P 29-45 %R doi:10.5194/nhess-24-29-2024 %T Compound flood impacts from Hurricane Sandy on New York City in climate-driven storylines %U https://doi.org/10.5194/nhess-24-29-2024 1 %X High impact events like Hurricane Sandy (2012) significantly affect society and decision-making around weather/climate adaptation. Our understanding of the potential effects of such events is limited to their rare historical occurrences. Climate change might alter these events to an extent that current adaptation responses become insufficient. Furthermore, internal climate variability in the current climate might also lead to slightly different events with possible larger societal impacts. Therefore, exploring high impact events under different conditions becomes important for (future) impact assessment. In this study, we create storylines of Sandy to assess compound coastal flooding on critical infrastructure in New York City under different scenarios, including climate change effects (on the storm and through sea level rise) and internal variability (variations in the storm's intensity and location). We find that 1 m of sea level rise increases average flood volumes by 4.2 times, while maximised precipitation scenarios (internal variability) lead to a 2.5-fold increase in flood volumes. The maximised precipitation scenarios impact inland critical infrastructure assets with low water levels, while sea level rise impacts fewer coastal assets though with high water levels. The diversity in hazards and impacts demonstrates the importance of building a set of relevant scenarios, including those representing the effects of climate change and internal variability. The integration of a modelling framework connecting meteorological conditions to local hazards and impacts provides relevant and accessible information that can directly be integrated into high impact event assessments. %0 journal article %@ 1561-8633 %A Krieger, D., Brune, S., Baehr, J., Weisse, R. %D 2024 %J Natural Hazards and Earth System Sciences %N 4 %P 1539-1554 %R doi:10.5194/nhess-24-1539-2024 %T Improving seasonal predictions of German Bight storm activity %U https://doi.org/10.5194/nhess-24-1539-2024 4 %X Extratropical storms are one of the major coastal hazards along the coastline of the German Bight, the southeastern part of the North Sea, and a major driver of coastal protection efforts. However, the predictability of these regional extreme events on a seasonal scale is still limited. We therefore improve the seasonal prediction skill of the Max Planck Institute Earth System Model (MPI-ESM) large-ensemble decadal hindcast system for German Bight storm activity (GBSA) in winter. We define GBSA as the 95th percentiles of three-hourly geostrophic wind speeds in winter, which we derive from mean sea-level pressure (MSLP) data. The hindcast system consists of an ensemble of 64 members, which are initialized annually in November and cover the winters of 1960/61–2017/18. We consider both deterministic and probabilistic predictions of GBSA, for both of which the full ensemble produces poor predictions in the first winter. To improve the skill, we observe the state of two physical predictors of GBSA, namely 70 hPa temperature anomalies in September, as well as 500 hPa geopotential height anomalies in November, in areas where these two predictors are correlated with winter GBSA. We translate the state of these predictors into a first guess of GBSA and remove ensemble members with a GBSA prediction too far away from this first guess. The resulting subselected ensemble exhibits a significantly improved skill in both deterministic and probabilistic predictions of winter GBSA. We also show how this skill increase is associated with better predictability of large-scale atmospheric patterns. %0 journal article %@ %A Ren, G., von Storch, H. %D 2024 %J Oxford Research Encyclopedia of Climate Science %R doi:10.1093/acrefore/9780190228620.013.957 %T On frequently used terms related to climate change %U https://doi.org/10.1093/acrefore/9780190228620.013.957 %X Using terms with the same meaning is a precondition of academic exchange and coordinated international actions to cope with the global climate issue. However, the understanding and usage of some terms in the climate change field are incompatible among researchers, policymakers, and publics. In particular, the Intergovernmental Panel on Climate Change (IPCC) and the United Nations Framework Convention on Climate Change have used significantly different definitions of climate change, which may result in unforeseen problems in coping with the global climate issue. Also, when referring to future changes, the terms climate change projection and climate prediction are frequently used inconsistently. Other terms not always used with the same meaning are global warming, global change, global climate change, abrupt climate change, climate change monitoring, climate change detection, and climate change attribution. With respect to the term climate change, it is suggested that it be defined in academic circles as a change in any key climate variables or climate extremes on timescales of multidecades or longer periods caused by any drivers (natural or human and external or internal), whereas the term climate variability should be used to refer to variations on all the spectrums of frequency provoked by natural internal drivers or on high-frequency spectrums caused by natural external drivers. Following the IPCC terminology, it is suggested that climate change projection be defined as estimating possible evolutions of the climate state in the future on scales of decades or longer, based on development scenarios and climate models, with the estimate considered possible, internally consistent, but not necessarily probable. It is also suggested that the term anthropogenic climate change be used to express large-scale climate change caused by various human activities, especially global warming caused by greenhouse gas emissions from human activities and the corresponding changes in other components of the climate system as noted in the IPCC reports and international climate negotiations. %0 journal article %@ 2366-7451 %A Borgers, R., Dirksen, M., Wijnant, I.L., Stepek, A., Stoffelen, A., Akhtar, N., Neirynck, J., Van de Walle, J., Meyers, J., P.M. van Lipzig, N.P.M. %D 2024 %J Wind Energy Science %N 3 %P 697-719 %R doi:https:/dx./doi.org/10.5194/wes-9-697-2024 %T Mesoscale modelling of North Sea wind resources with COSMO-CLM: model evaluation and impact assessment of future wind farm characteristics on cluster-scale wake losses %U https://doi.org/https:/dx./doi.org/10.5194/wes-9-697-2024 3 %X As many coastal regions experience a rapid increase in offshore wind farm installations, inter-farm distances become smaller, with a tendency to install larger turbines at high capacity densities. It is, however, not clear how the wake losses in wind farm clusters depend on the characteristics and spacing of the individual wind farms. Here, we quantify this based on multiple COSMO-CLM simulations, each of which assumes a different, spatially invariant combination of the turbine type and capacity density in a projected, future wind farm layout in the North Sea. An evaluation of the modelled wind climate with mast and lidar data for the period 2008–2020 indicates that the frequency distributions of wind speed and wind direction at turbine hub height are skillfully modelled and the seasonal and inter-annual variations in wind speed are represented well. The wind farm simulations indicate that for a typical capacity density and for SW winds, inter-farm wakes can reduce the capacity factor at the inflow edge of wind farms from 59 % to between 54 % and 30 % depending on the proximity, size and number of the upwind farms. The efficiency losses due to intra- and inter-farm wakes become larger with increasing capacity density as the layout-integrated, annual capacity factor varies between 51.8 % and 38.2 % over the considered range of 3.5 to 10 MW km−2. Also, the simulated efficiency of the wind farm layout is greatly impacted by switching from 5 MW turbines to next-generation, 15 MW turbines, as the annual energy production increases by over 27 % at the same capacity density. In conclusion, our results show that the wake losses in future wind farm clusters are highly sensitive to the inter-farm distances and the capacity densities of the individual wind farms and that the evolution of turbine technology plays a crucial role in offsetting these wake losses. %0 journal article %@ 2196-6311 %A Arlinghaus, P., Schrum, C., Kröncke, I., Zhang, W. %D 2024 %J Earth Surface Dynamics %P 537-558 %R doi:10.5194/esurf-12-537-2024 %T Benthos as a key driver of morphological change in coastal regions %U https://doi.org/10.5194/esurf-12-537-2024 %X Benthos has long been recognized as an important factor influencing local sediment stability, deposition, and erosion rates. However, its role in long-term (annual to decadal scale) and large-scale coastal morphological change remains largely speculative. This study aims to derive a quantitative understanding of the importance of benthos in the morphological development of a tidal embayment (Jade Bay) as representative of tidal coastal regions. To achieve this, we first applied a machine-learning-aided species abundance model to derive a complete map of benthos (functional groups, abundance, and biomass) in the study area, based on abundance and biomass measurements. The derived data were used to parameterize the benthos effect on sediment stability, erosion rates and deposition rates, erosion and hydrodynamics in a 3-dimensional hydro-eco-morphodynamic model, which was then applied to Jade Bay to hindcast the morphological and sediment change for 2000–2009. Simulation results indicate significantly improved performance with the benthos effect included. Simulations including benthos show consistency with measurements regarding morphological and sediment changes, while abiotic drivers (tides, storm surges) alone result in a reversed pattern in terms of erosion and deposition contrary to measurement. Based on comparisons among scenarios with various combinations of abiotic and biotic factors, we further investigated the level of complexity of the hydro-eco-morphodynamic models that is needed to capture long-term and large-scale coastal morphological development. The accuracy in the parameterization data was crucial for increasing model complexity. When the parameterization uncertainties were high, the increased model complexity decreased the model performance. %0 journal article %@ 2352-4855 %A Nguyen, T.T., Staneva, J., Grayek, S., Bonaduce, A., Hagemann, S., Pham, N.T., Kumar, R., Rakovec, O. %D 2024 %J Regional Studies in Marine Science %P 103476 %R doi:10.1016/j.rsma.2024.103476 %T Impacts of Extreme River Discharge on Coastal Dynamics and Environment: Insights from High-Resolution Modeling in the German Bight %U https://doi.org/10.1016/j.rsma.2024.103476 %X The intricate relationship between extreme river discharge and its consequential effects on coastal basins’ environment and dynamics remains a subject of profound significance. The impact of extreme river discharge on coastal basin dynamics and environment is a complex phenomenon, particularly relevant in the context of the German Bight. The inflow of freshwater from rivers into the German Bight plays a crucial role in driving the complex thermohaline circulation. Addressing the challenges posed by local hydro-meteorological extremes, compounded by strong wind waves, currents and tides is vital for comprehensive impact assessment. Utilizing the Geesthacht Coupled cOAstal model SysTem (GCOAST) with high-resolution configuration, we investigate the sensitivity of the thermohaline properties to the river forcings. By incorporating river discharge as lateral land forcing in a coupled hydrodynamic and wave model, we conducted five sensitivity experiments. Our findings reveal that the simulated temperatures closely match measurements in all experiments. The salinity, however, is remarkably sensitive to the variation of freshwater from the rivers Elbe and Ems in the German Bight, causing the haline stratification. The statistical evaluation, as demonstrated by the Taylor diagram at the Marnet DB station, underscores the skill of the Mesoscale Hydrologic Model (mHM) in generating the freshwater discharge that drives the thermohaline characteristics of the German Bight, especially during events like the June 2013 flooding. Significantly, the use of climatological runoff proves to be ineffective in simulating stratification during extreme flooding events. In essence, this investigation enhances our understanding of the pivotal role played by high-frequency river freshwater buoyancy. It emerges as a driving force behind salinity fluctuations during extreme floods, providing valuable insights into coastal dynamics within the German Bight. %0 journal article %@ 2475-9066 %A Lemmen, C., Hokamp, S., Örey, S., Scheffran, J. %D 2024 %J The Journal of Open Source Software %N 95 %P 5731 %R doi:10.21105/joss.05731 %T Viable North Sea (ViNoS): A NetLogo Agent-based Model of German North Sea Small-scale fisheries %U https://doi.org/10.21105/joss.05731 95 %X Viable North Sea (ViNoS) is an Agent-based Model (ABM) of the German Small-scale Fisheries. As a Social-Ecological Systems model it focusses on the adaptive behaviour of fishers facing regulatory, economic, and resource changes. Small-scale fisheries are an important part both of the cultural perception of the German North Sea coast and of its fishing industry. These fisheries are typically family-run operations that use smaller boats and bottom trawling gear to catch a variety of demersal species, foremost plaice, sole, and brown shrimp. Fishers in the North Sea face area competition with other uses of the sea—long practiced ones like shipping, gas exploration and sand extraction, and currently increasing ones like marine protection and offshore wind farming: German authorities released a maritime spatial plan implementing (1) the need for 30% of protection areas demanded by the United Nations High Seas Treaty and (2) aiming at up to 70 GW of domestic offshore wind power generation by 2045; the European Union is aiming to reduce fisheries in all Marine Protected Areas. Fisheries in the North Sea also have to adjust to the northward migration of their established resources following the climate heating of the water. And they have to re-evaluate their economic balance by figuring in the foreseeable rise in oil price and the need for re-investing into their aged fleet. %0 journal article %@ 1616-7341 %A Saçu, Ş., Şen, O., Erdik, T., Öztürk, İ., Stanev, E.V. %D 2024 %J Ocean Dynamics %P 287-305 %R doi:10.1007/s10236-024-01604-z %T Water exchange in the Dardanelles: variations on synoptic to interannual time scales %U https://doi.org/10.1007/s10236-024-01604-z %X The bidirectional mass exchange between the Marmara Sea and the Aegean Sea provides one part of the critical hydrodynamic links between the Black Sea and the Mediterranean Sea. In this study, we examined exchange in the Dardanelles based on a 3-D numerical model simulation covering an 11-year period under realistic atmospheric forcing. The model includes the Black Sea, the Marmara Sea, and a part of the Aegean Sea to include the remote effects of basin dynamics. The main features as one-, two-, and three-layered flow structures are successfully reproduced by the model in comparison to earlier observations. It is found that the strait is subject to submaximal exchange by only one control near the Nara Pass. According to long-term modeling results, most variability occurs on synoptic time scales, and wind stress has a dominant role in those variations. The seasonal and interannual variability of exchange flow is relatively low and displays a close relationship with freshwater input to the Black Sea. %0 journal article %@ 2296-7745 %A Hosseini, S.T., Stanev, E., Pein, J., Valle-Levinson, A., Schrum, C. %D 2023 %J Frontiers in Marine Science %P 1152625 %R doi:10.3389/fmars.2023.1152625 %T Longitudinal and Lateral Circulation and Tidal Impacts in Salt-Plug Estuaries %U https://doi.org/10.3389/fmars.2023.1152625 %X This study presents a comparison of forcings between density gradient and tides in idealized funnel-shaped salt-plug estuaries. Three-dimensional numerical model results also examine longitudinal and lateral circulations. In salt-plug estuaries, a positive longitudinal estuarine circulation is observed landward of a salinity maximum zone or salt plug. Seaward of the salt plug, the estuary shows an inverse circulation cell. The longitudinal flows show a fortnightly variability inside the salt plug. Also, the salt plug is saltier in spring tides than in neap tidal cycles mainly owing to higher landward salt transport by tidal advection during the spring tides. The lateral circulation and divergence dv/dy have the influence of Coriolis acceleration. In the absence of Earth’s rotation, the tidally averaged lateral circulations have nearly the same directions within the positive and inverse cells. Directions of lateral flow reverse in the salt-plug area. Inside this area, the lateral circulation also shows clear neap–spring variability, including downwelling cells during spring tides and upwelling in neap tides. The salinity maximum zone exhibits a vertically homogeneous condition particularly in meso-tidal salt-plug estuaries. Finally, this study introduces the threshold of “log(tidal Froude number)=3” (tidal forcing 3 orders of magnitude ≥ density gradients) for salt-plug estuaries as the condition under which the tidal forcing can overcome the density gradient, and consequently salinity inside the salt plug zone is reinforced by tides with a landward movement. This robust salinity maximum zone is also identified by a high Ekman number (log(Ekman number)>0.25). %0 journal article %@ 2698-4016 %A Tim, N., Zorita, E., Hünicke, B., Ivanciu, I. %D 2023 %J Weather and Climate Dynamics %N 2 %P 381-397 %R doi:10.5194/wcd-4-381-2023 %T The impact of the Agulhas Current system on precipitation in southern Africa in regional climate simulations covering the recent past and future %U https://doi.org/10.5194/wcd-4-381-2023 2 %X The southern African climate is strongly impacted by climate change. Precipitation is a key variable in this region, as it is linked to agriculture and water supply. Simulations with a regional atmospheric model over the past decades and the 21st century display a decrease in the past precipitation over some coastal areas of South Africa and an increase over the rest of southern Africa. However, precipitation is projected to decrease over the whole southern part of the domain in the future. This study shows that the Agulhas Current system, including the current and the leakage, which surrounds the continent in the east and south, impacts this precipitation trend. A reduction in the strength of the Agulhas Current is linked to a reduction in precipitation along the southeast coast. The Agulhas leakage, the part of the Agulhas Current that leaves the system and flows into the South Atlantic, impacts winter precipitation in the southwest of the continent. A more intense Agulhas leakage is linked to a reduction in precipitation in this region. %0 journal article %@ 2296-7745 %A Christiansen, N., Carpenter, J.R., Daewel, U., Suzuki, N., Schrum, C. %D 2023 %J Frontiers in Marine Science %P 1178330 %R doi:10.3389/fmars.2023.1178330 %T The large-scale impact of anthropogenic mixing by offshore wind turbine foundations in the shallow North Sea %U https://doi.org/10.3389/fmars.2023.1178330 %X Structure drag from offshore wind turbines and its physical impacts on the marine environment of the German Bight are investigated in this study. The flow past vertical cylinders, such as wind turbine foundations, and associated turbulent mixing has long been studied, but questions remain about anticipated regional implications of offshore wind infrastructure on physical and biogeochemical conditions. Here, we present two existing modeling approaches for simulating wind turbine foundation effects in regional ocean models and discuss the problematic use of very high resolution in hydrostatic modeling. By implementing a low-resolution structure drag parameterization in an unstructured-grid model, we demonstrate the impacts of monopile drag on hydrodynamic conditions, validated against recent in-situ measurements. Although the anthropogenic mixing is confined at wind farm sites, our simulations show that structure-induced mixing affects much larger, regional scales. The additional turbulence production emerges as the driving mechanism behind the monopile impacts, leading to changes in both the current velocities and stratification, with magnitudes of about 10%, similar in magnitude to regional annual and interannual variabilities. This study provides new insights into the hydrodynamic impact of offshore wind farms at their current development levels and emphasizes the need for further research in view of potential restructuring of the future coastal environment. %0 journal article %@ 2296-7745 %A Grayek, S., Wiese, A., Ho-Hagemann, H.T.M., Staneva, J. %D 2023 %J Frontiers in Marine Science %P 1104027 %R doi:10.3389/fmars.2023.1104027 %T Added Value of Including Waves into a Coupled Atmosphere-Ocean Model System within the North Sea Area %U https://doi.org/10.3389/fmars.2023.1104027 %X In this study, the effects of fully coupling the atmosphere, waves, and ocean compared with two-way-coupled simulations of either atmosphere and waves or atmosphere and ocean are analyzed. Two-year-long simulations (2017 and 2018) are conducted using the atmosphere–ocean–wave (AOW) coupled system consisting of the atmosphere model CCLM, the wave model WAM, and the ocean model NEMO. Furthermore, simulations with either CCLM and WAM or CCLM and NEMO are done in order to estimate the impacts of including waves or the ocean into the system. For the North Sea area, it is assessed whether the influence of the coupling of waves and ocean on the atmosphere varies throughout the year and whether the waves or the ocean have the dominant effect on the atmospheric model. It is found that the effects of adding the waves into the system already consisting of atmosphere and ocean model or adding the ocean to the system of atmosphere and wave model vary throughout the year. Which component has a dominant effect and whether the effects enhance or diminish each other depends on the season and variable considered. For the wind speed, during the storm season, adding the waves has the dominant effect on the atmosphere, whereas during summer, adding the ocean has a larger impact. In summer, the waves and the ocean have similar influences on mean sea level pressure (MSLP). However, during the winter months, they have the opposite effect. For the air temperature at 2 m height (T_2m), adding the ocean impacts the atmosphere all year around, whereas adding the waves mainly influences the atmosphere during summer. This influence, however, is not a straight feedback by the waves to the atmosphere, but the waves affect the ocean surface temperature, which then also feedbacks to the atmosphere. Therefore, in this study we identified a season where the atmosphere is affected by the interaction between the waves and the ocean. Hence, in the AOW-coupled simulation with all three components involved, processes can be represented that uncoupled models or model systems consisting of only two models cannot depict. %0 journal article %@ 1991-959X %A Bieser, J., Amptmeijer, D.J., Daewel, U., Kuss, J., Soerensen, A.L., Schrum, C. %D 2023 %J Geoscientific Model Development %N 9 %P 2649-2688 %R doi:10.5194/gmd-16-2649-2023 %T The 3D biogeochemical marine mercury cycling model MERCY v2.0 – linking atmospheric Hg to methylmercury in fish %U https://doi.org/10.5194/gmd-16-2649-2023 9 %X Mercury (Hg) is a pollutant of global concern. Due to anthropogenic emissions, the atmospheric and surface ocean Hg burden has increased substantially since preindustrial times. Hg emitted into the atmosphere gets transported on a global scale and ultimately reaches the oceans. There it is transformed into highly toxic methylmercury (MeHg) that effectively accumulates in the food web. The international community has recognized this serious threat to human health and in 2017 regulated Hg use and emissions under the UN Minamata Convention on Mercury. Currently, the first effectiveness evaluation of the Minamata Convention is being prepared, and, in addition to observations, models play a major role in understanding environmental Hg pathways and in predicting the impact of policy decisions and external drivers (e.g., climate, emission, and land-use change) on Hg pollution. Yet, the available model capabilities are mainly limited to atmospheric models covering the Hg cycle from emission to deposition. With the presented model MERCY v2.0 we want to contribute to the currently ongoing effort to improve our understanding of Hg and MeHg transport, transformation, and bioaccumulation in the marine environment with the ultimate goal of linking anthropogenic Hg releases to MeHg in seafood. Here, we present the equations and parameters implemented in the MERCY model and evaluate the model performance for two European shelf seas, the North and Baltic seas. With the model evaluation, we want to establish a set of general quality criteria that can be used for evaluation of marine Hg models. The evaluation is based on statistical criteria developed for the performance evaluation of atmospheric chemistry transport models. We show that the MERCY model can reproduce observed average concentrations of individual Hg species in water (normalized mean bias: HgT 17 %, Hg0 2 %, MeHg −28 %) in the two regions mentioned above. Moreover, it is able to reproduce the observed seasonality and spatial patterns. We find that the model error for HgT(aq) is mainly driven by the limitations of the physical model setup in the coastal zone and the availability of data on Hg loads in major rivers. In addition, the model error in calculating vertical mixing and stratification contributes to the total HgT model error. For the vertical transport we find that the widely used particle partitioning coefficient for organic matter of log(kd)=5.4 is too low for the coastal systems. For Hg0 the model performance is at a level where further model improvements will be difficult to achieve. For MeHg, our understanding of the processes controlling methylation and demethylation is still quite limited. While the model can reproduce average MeHg concentrations, this lack of understanding hampers our ability to reproduce the observed value range. Finally, we evaluate Hg and MeHg concentrations in biota and show that modeled values are within the range of observed levels of accumulation in phytoplankton, zooplankton, and fish. The model performance demonstrates the feasibility of developing marine Hg models with similar predictive capability to established atmospheric chemistry transport models. Our findings also highlight important knowledge gaps in the dynamics controlling methylation and bioaccumulation that, if closed, could lead to important improvements of the model performance. %0 journal article %@ 2296-7745 %A Pein, J., Staneva, J., Mayer, B., Palmer, M.D., Schrum, C. %D 2023 %J Frontiers in Marine Science %P 1102485 %R doi:10.3389/fmars.2023.1102485 %T A framework for estuarine future sea level scenarios: Response of the industrialised Elbe estuary to projected mean sea level rise and internal variability %U https://doi.org/10.3389/fmars.2023.1102485 %X In this study, we apply probabilistic estimates of mean sea level (MSL) rise and a sub-set of regional climate model ensemble simulations to force a numerical model of the southern North Sea, downscaling projected sea level variability to the Elbe estuary that serves as a prototype for an industrialised meso-tidal estuary. The specific forcing combination enables a localised projection of future estuarine hydrodynamics accounting for the spread of projected global sea level rise and the spread of the regional climate projection due to internal variability. Under the applied high-emission scenario, the Elbe estuary shows high decadal rates of mean water level (MWL) rise beyond 19 mm y-1, increase in the tidal range of up to 14 mm y-1 and increase in extreme water levels of up to 18 mm y-1. The bandwidth of the estuarine response is also high. For example, the range of average monthly extreme water levels is up to 0.57 m due to the spread of projected global sea level rise, up to 0.58 m due to internal variability whereas seasonal range attains 1.99 m locally. In the lower estuary, the spread of projected global sea level rise dominates over internal variability. Internal variability, represented by ensemble spread, notably impacts the range of estuarine water levels and tidal current asymmetry in the shallow upper estuary. This area demonstrates large seasonal fluctuations of MWLs, the M2 tidal amplitude and monthly extreme water levels. On the monthly and inter-annual time scales, the MWL and M2 amplitude reveal opposite trends, indicative of a locally non-linear response to the decadal MSL rise enforced at the open boundary. Overall, imposed by the climate projections decadal change and MSL rise enhance the horizontal currents and turbulent diffusivities whereas internal variability locally mitigates sea level rise–driven changes in the water column. This work establishes a framework for providing consistent regionalised scenario-based climate change projections for the estuarine environment to support sustainable adaptation development. %0 journal article %@ 2296-7745 %A Meyerjürgens, J., Ricker, M., Aden, C., Albinus, M., Barrelet, J., Freund, H., Hahner, F., Lettmann, K.A., Mose, I., Schaal, P., Schöneich-Argent, R.I., Stanev, E.V., Wolff, J.O., Zielinski, O., Badewien, T.H. %D 2023 %J Frontiers in Marine Science %P 1148714 %R doi:10.3389/fmars.2023.1148714 %T Sources, pathways, and abatement strategies of macroplastic pollution: an interdisciplinary approach for the southern North Sea %U https://doi.org/10.3389/fmars.2023.1148714 %X The issue of marine plastic pollution has been extensively studied by various scientific disciplines in recent decades due to its global threat. However, owing to its complexity, it requires an interdisciplinary approach to develop effective management strategies. The multidisciplinary scientific approach presented here focuses on understanding the sources and pathways of macroplastic litter and developing abatement strategies in the southern North Sea region. Over 2.5 years, more than 63,400 biodegradable wooden drifters were deployed with the help of citizen science to study the sources, pathways, and accumulation areas of floating marine litter. Rivers act as sinks of most of the floating marine litter released within their waterways. Short-term field experiments were also conducted to analyse the hydrodynamic and atmospheric processes that govern the transport of floating litter particles at the sea surface. Numerical models were used to examine the transport of virtual litter particles in the entire North Sea and in coastal regions. It was found that there are no permanent accumulation areas in the North Sea, and the Skagerrak and fronts can increase the residence times of floating marine litter and favour sinking. Field surveys revealed that the majority of litter objects originate from fisheries and consumer waste. To develop effective abatement strategies, the key stakeholder landscape was analysed on a regional level. The interdisciplinary approach developed in this study highlights the importance of synergizing scientific resources from multiple disciplines for a better understanding of marine plastic pollution and the development of effective management strategies. %0 journal article %@ 2296-7745 %A Chen, W., Jacob, B., Valle-Levinson, A., Stanev, E., Staneva, J., Badewien, T.H. %D 2023 %J Frontiers in Marine Science %P 1105626 %R doi:10.3389/fmars.2023.1105626 %T Subtidal secondary circulation induced by eddy viscosity-velocity shear covariance in a predominantly well-mixed tidal inlet %U https://doi.org/10.3389/fmars.2023.1105626 %X The secondary circulation in a predominantly well-mixed estuarine tidal inlet is examined with three-dimensional numerical simulations of the currents and density field in the German Bight. Simulations analyze two complete neap and spring tidal cycles, inspired by cross-section measurements in the tidal inlet, with a focus on subtidal time scales. The study scrutinizes the lateral momentum balance and quantifies the individual forces that drive the residual flow on the cross-section. Forces (per unit mass) from the covariance between eddy viscosity and tidal vertical shear (ESCO) play a role in the lateral momentum budget. During neap tide, the ESCO-driven flow is weak. Accelerations driven by advection dominate the subtidal secondary circulation, which shows an anti-clockwise rotation. During spring tide, the ESCO acceleration, together with the baroclinicity and centrifugal acceleration, drives a clockwise circulation (looking seaward). This structure counteracts the advection-induced flow, leading to the reversal of the secondary circulation. The decomposition of the lateral ESCO term contributors reveals that the difference in ESCO between neap and spring tides is attributed to the change in the vertical structure of lateral tidal currents, which are maximum near the bottom in spring tide. The findings highlight the role of the tidally varying vertical shears in the ESCO mechanism. %0 journal article %@ 1561-8633 %A Heinrich, P., Hagemann, S., Weisse, R., Schrum, C., Daewel, U., Gaslikova, L. %D 2023 %J Natural Hazards and Earth System Sciences %N 5 %P 1967-1985 %R doi:10.5194/nhess-23-1967-2023 %T Compound flood events: analysing the joint occurrence of extreme river discharge events and storm surges in northern and central Europe %U https://doi.org/10.5194/nhess-23-1967-2023 5 %X The simultaneous occurrence of extreme events gained more and more attention from scientific research in the last couple of years. Compared to the occurrence of single extreme events, co-occurring or compound extremes may substantially increase risks. To adequately address such risks, improving our understanding of compound flood events in Europe is necessary and requires reliable estimates of their probability of occurrence together with potential future changes. In this study compound flood events in northern and central Europe were studied using a Monte Carlo-based approach that avoids the use of copulas. Second, we investigate if the number of observed compound extreme events is within the expected range of 2 standard deviations of randomly occurring compound events. This includes variations of several parameters to test the stability of the identified patterns. Finally, we analyse if the observed compound extreme events had a common large-scale meteorological driver. The results of our investigation show that rivers along the west-facing coasts of Europe experienced a higher amount of compound flood events than expected by pure chance. In these regions, the vast majority of the observed compound flood events seem to be related to the cyclonic westerly general weather pattern (Großwetterlage). %0 journal article %@ 2041-1723 %A Lehmann, N., Stacke, T., Lehmann, S., Lantuit, H., Gosse, J., Mears, C., Hartmann, J., Thomas, H. %D 2023 %J Nature Communications %P 1648 %R doi:10.1038/s41467-023-37165-w %T Alkalinity responses to climate warming destabilise the Earth´s thermostat %U https://doi.org/10.1038/s41467-023-37165-w %X Alkalinity generation from rock weathering modulates Earth’s climate at geological time scales. Although lithology is thought to dominantly control alkalinity generation globally, the role of other first-order controls appears elusive. Particularly challenging remains the discrimination of climatic and erosional influences. Based on global observations, here we uncover the role of erosion rate in governing riverine alkalinity, accompanied by areal proportion of carbonate, mean annual temperature, catchment area, and soil regolith thickness. We show that the weathering flux to the ocean will be significantly altered by climate warming as early as 2100, by up to 68% depending on the environmental conditions, constituting a sudden feedback of ocean CO2 sequestration to climate. Interestingly, warming under a low-emissions scenario will reduce terrestrial alkalinity flux from mid-latitudes (–1.6 t(bicarbonate) a−1 km−2) until the end of the century, resulting in a reduction in CO2 sequestration, but an increase (+0.5 t(bicarbonate) a−1 km−2) from mid-latitudes is likely under a high-emissions scenario, yielding an additional CO2 sink. %0 journal article %@ 1561-8633 %A Wahle, K., Stanev, E., Staneva, J. %D 2023 %J Natural Hazards and Earth System Sciences %N 2 %P 415-428 %R doi:10.5194/nhess-23-415-2023 %T Detecting anomalous sea-level states in North Sea tide gauge data using an autoassociative neural network %U https://doi.org/10.5194/nhess-23-415-2023 2 %X The sea level in the North Sea is densely monitored by tide gauges. The data they provide can be used to solve different scientific and practical problems, including the validation of numerical models and the detection of extreme events. This study focuses on the detection of sea-level states with anomalous spatial correlations using autoassociative neural networks (AANNs), trained with different sets of observation- and model-based data. Such sea-level configurations are related to nonlinear ocean dynamics; therefore, neural networks appear to be the right candidate for their identification. The proposed network can be used to accurately detect such anomalies and localize them. We demonstrate that the atmospheric conditions under which anomalous sea-level states occur are characterized by high wind tendencies and pressure anomalies. The results show the potential of AANNs for accurately detecting the occurrence of such events. We show that the method works with AANNs trained on tide gauge records as well as with AANN trained with model-based sea surface height outputs. The latter can be used to enhance the representation of anomalous sea-level events in ocean models. Quantitative analysis of such states may help assess and improve numerical model quality in the future as well as provide new insights into the nonlinear processes involved. This method has the advantage of being easily applicable to any tide gauge array without preprocessing the data or acquiring any additional information. %0 journal article %@ 0037-0746 %A Wilckens, H., Schwenk, T., Lüdmann, T., Betzler, C., Zhang, W., Chen, J., Hernández-Molina, F., Lefebvre, A., Cattaneo, A., Spieß, V., Miramontes, E. %D 2023 %J Sedimentology %N 5 %P 1472-1495 %R doi:10.1111/sed.13093 %T Factors controlling the morphology and internal sediment architecture of moats and their associated contourite drifts %U https://doi.org/10.1111/sed.13093 5 %X The interaction of sedimentary systems with oceanographic processes in deep-water environments is not well understood yet, despite its importance for palaeoenvironmental reconstructions, and for a full understanding of source-to-sink sediment transport. The aim of this study is to improve the understanding of how contourite moats, elongated depressions formed by bottom currents associated with contourite drifts, develop and of the link between moat-drift system morphology and bottom current dynamics. This study provides a systematic comparison of 185 cross-sections of moat-drift systems distributed at 39 different locations worldwide, and a detailed analysis of the morphology of six moats that cover a wide range of typical geological and hydrodynamic settings. Additionally, in situ measured current data were analysed to better link hydrodynamics to moat morphology. The median of all profiles across all moat-drift systems reveals a 50 m relief, a width of 2.3 km, a relief to width ratio of 0.022, a slope angle of 6°, a drift angle of 3° and a concave-up shaped morphology. Moats can be over 100 km long. Some moats are driven by sediment erosion while others are depositional and primarily exist due to differential sedimentation inside the moat compared to the drift alongside the moat. A new sub-classification of moat-drift systems based on their stratigraphy is proposed. This classification distinguishes moats depending on the degree of erosion versus deposition. No relation is found between latitude and moat-drift morphology or stratigraphy in the analysed examples. The combined data indicate that a steeper slope focuses the current more than a gentle slope, resulting in an increase of the relief-width ratio and drift angle. Thus, this study provides new insides into the interaction of ocean currents with sedimentary morphology, which thereby affects the evolution of a poorly understood deepwater sedimentary system. %0 journal article %@ 0967-0645 %A Xu, Y., Zhou, F., Meng, Q., Zeng, D., Yan, T., Zhang, W. %D 2023 %J Deep-Sea Research Part II %P 105261 %R doi:10.1016/j.dsr2.2023.105261 %T How do topography and thermal front influence the water transport from the northern Laotieshan Channel to the Bohai Sea interior in summer? %U https://doi.org/10.1016/j.dsr2.2023.105261 %X Water renewal through the Bohai Strait largely dominates the water quality of the semi-enclosed Bohai Sea (BS), which connects only to the northern Yellow Sea (NYS) through the strait. Although the peak water transport through the Bohai Strait occurs in summer, the spatially averaged water residence time of the BS shows no significant decrease compared to other periods. A three-dimensional model is applied to unravel the detailed structure and dynamic processes of the summertime NYS water transport from the northern Laotieshan Channel to the BS interior. Model results from both climatological and hindcasting cases show that despite a large amount of the NYS water enters the strait, they are confined to the Laotieshan Channel between the Central Bank and Dalian surrounded by a strong Ω-shaped tidal front and could not move further north into the Liaodong Bay. The strong along-front flow steered by the topography forms a counter-clockwise circulation pattern in the strait zone, resulting in most of water southward movement east of the Central Bank, then join the outflow south of the strait and leave for the NYS. The Central Bank and the topographic sill north of the Laotieshan Channel act as a barrier that significantly reduces the water exchange between the strait zone and the BS interior, in particular the Liaodong Bay. Particle-tracking experiments suggest that less than 10% of particles released in the NYS could finally reach the BS interior, and among of them only a small portion of them could move further north into the Liaodong Bay. Momentum diagnostics suggest that the water transport northwest of the strait is dominated by geostrophic balance in the Ω-shaped frontal region. Sensitivity experiments indicate that tides promote the surface water transport from the NYS to the BS interior. The realistic wind forcing including synoptic events may facilitate the water transport from the strait to the BS interior by modulating the barotropic and baroclinic pressure gradient than that with the climatological wind case. %0 journal article %@ 2169-897X %A Tian, D., Zhang, H., Wang, S., Zhang, W., Sun, X., Zhou, Y., Zheng, G., Jiang, H., Yang, S., Zhou, F. %D 2023 %J Journal of Geophysical Research : Atmospheres %N 3 %P e2022JD037235 %R doi:10.1029/2022JD037235 %T Sea Surface Wind Structure in the Outer Region of Tropical Cyclones Observed by Wave Gliders %U https://doi.org/10.1029/2022JD037235 3 %X Understanding the sea surface wind structure during tropical cyclones (TCs) is the key for study of ocean response and parameterization of air-sea surface in numerical simulation. However, field observations are scarce. In 2019, three wave gliders were deployed in the South China Sea and the adjacent Western Pacific region, which acquired sea surface wind structure of eight TCs. Analysis of the field data suggests that the wave glider-observed surface winds are consistent with most analysis/reanalysis data (i.e., ERA5, Cross-Calibrated Multi-Platform, and National Centers for Environmental Prediction-Global Data Assimilation System) and Soil Moisture Active Passive. Both wave glider observations and analysis/reanalysis data indicate that TC wind fields induce an obvious increase in speed toward the sea surface together with a sharp change in direction, showing an asymmetric wind structure which is sensitive to TC translation speed and intensity. Larger mean values of wind speed and inflow angle are located on the right side along TC tracks. The inflow angle shows a highly dynamic dependence on the radial distance from the TC center, the TC intensity, as well as the TC-relative azimuth. Comparisons between field observations and theoretical models indicate that the most widely used, ideal TC wind profile models can largely represent the observed sea surface wind structure, but generally underestimate the wind speed due to lack of consideration of background wind. Moreover, simple ideal models (e.g., the modified Rankine vortex model) may outperform complex models when accurate information of TCs is limited. Wave glider observations have potential for better understanding of air-sea exchanges and for improvements of the corresponding parameterization schemes. %0 journal article %@ 2296-7745 %A Ma, M., Zhang, W., Chen, W., Deng, J., Schrum, C. %D 2023 %J Frontiers in Marine Science %P 1072080 %R doi:10.3389/fmars.2023.1072080 %T Impacts of morphological change and sea-level rise on stratification in the Pearl River Estuary %U https://doi.org/10.3389/fmars.2023.1072080 %X The Pearl River Delta (PRD), where several megacities are located, has undergone drastic morphological changes caused by anthropogenic impact during the past few decades. In its main estuary, the water area has been reduced by 21% whilst the average water depth has increased by 2.24 m from 1970s to 2010s. The mainly human-induced morphological change together with sea level rise has jointly led to a remarkable change in the water stratification. However, the spatial and temporal variability of stratification in the estuary and associated driving mechanisms remain less understood. In this study, stratification in the Pearl River Estuary (PRE) in response to morphological change and external forcing is investigated by 3-dimensional numerical modeling. Simulation results indicate that stratification in the PRE exhibits distinct spatial and temporal variabilities. At a tidal-to-monthly time scale, variation of stratification is mainly driven by advection and straining through tidal forcing. At a monthly-to-seasonal scale, monsoon-driven river runoff and associated plume and fronts dominate the variation of stratification. Human-induced morphological change leads to an enhancement of stratification by up to four times in the PRE. Compared to an overwhelming human impact in the past few decades, future sea level rise would further enhance stratification, but to a much lesser extent than past human impacts. In addition, stratification in different areas of the estuary also responds differently to the driving factors. The western shoal of the estuary is most sensitive to changes in morphology and sea level due to its shallowness, followed by the channels and other parts of the estuary, which are less sensitive. %0 journal article %@ 1023-5809 %A von Storch, H. %D 2023 %J Nonlinear Processes in Geophysics %N 1 %P 31-36 %R doi:10.5194/npg-30-31-2023 %T Brief communication: Climate science as a social process – history, climatic determinism, Mertonian norms and post-normality %U https://doi.org/10.5194/npg-30-31-2023 1 %X Climate science finds itself in a “post-normal” condition, which leads to a frequent dominance of political utility over methodical rigor. %0 journal article %@ 2169-9275 %A Liu, X., Köhl, A., Stammer, D. %D 2023 %J Journal of Geophysical Research : Oceans %N 1 %P e2022JC018796 %R doi:10.1029/2022JC018796 %T Causes for Atlantic Freshwater Content Variability in the GECCO3 Ocean Synthesis %U https://doi.org/10.1029/2022JC018796 1 %X Regional freshwater content (FWC) changes are studied over the period 1961–2018 using the GECCO3 ocean synthesis. In four dynamically distinct regions of the Atlantic, the study identifies causes for FWC variability with a focus on interannual and decadal time-scale changes. Results show that in each region, it is a combination of the surface freshwater flux and the net freshwater transport across the region's boundaries that act jointly in changing the respective FWC. Surface flux mainly contributes to the FWC variability on multi-decadal time scales. The impact of surface flux also increases toward the tropics. On shorter time scales, it is especially horizontal transport fluctuations, leading to FWC changes in mid and high latitudes. Going from north to the south, the transport across a single meridional boundary becomes less correlated with the FWC changes but the net transport across both boundaries plays an increasingly important role. Moreover, the subpolar box is mainly gyre driven, which differs from the other two, essentially overturning driven, North Atlantic boxes. In the tropical Atlantic, the shallow overturning cell and the deep overturning contribute about equal amounts to the freshwater variations. %0 journal article %@ 1561-8633 %A Teutsch, I., Brühl, M., Weisse, R., Wahls, S. %D 2023 %J Natural Hazards and Earth System Sciences %N 6 %P 2053-2073 %R doi:10.5194/nhess-23-2053-2023 %T Contribution of solitons to enhanced rogue wave occurrence in shallow depths: a case study in the southern North Sea %U https://doi.org/10.5194/nhess-23-2053-2023 6 %X The shallow waters off the coast of Norderney in the southern North Sea are characterised by a higher frequency of rogue wave occurrences than expected. Here, rogue waves refer to waves exceeding twice the significant wave height. The role of nonlinear processes in the generation of rogue waves at this location is currently unclear. Within the framework of the Korteweg–de Vries (KdV) equation, we investigated the discrete soliton spectra of measured time series at Norderney to determine differences between time series with and without rogue waves. For this purpose, we applied a nonlinear Fourier transform (NLFT) based on the Korteweg–de Vries equation with vanishing boundary conditions (vKdV-NLFT). At measurement sites where the propagation of waves can be described by the KdV equation, the solitons in the discrete nonlinear vKdV-NLFT spectrum correspond to physical solitons. We do not know whether this is the case at the considered measurement site. In this paper, we use the nonlinear spectrum to classify rogue wave and non-rogue wave time series. More specifically, we investigate if the discrete nonlinear spectra of measured time series with visible rogue waves differ from those without rogue waves. Whether or not the discrete part of the nonlinear spectrum corresponds to solitons with respect to the conditions at the measurement site is not relevant in this case, as we are not concerned with how these spectra change during propagation. For each time series containing a rogue wave, we were able to identify at least one soliton in the nonlinear spectrum that contributed to the occurrence of the rogue wave in that time series. The amplitudes of these solitons were found to be smaller than the crest height of the corresponding rogue wave, and interaction with the continuous wave spectrum is needed to fully explain the observed rogue wave. Time series with and without rogue waves showed different characteristic soliton spectra. In most of the spectra calculated from rogue wave time series, most of the solitons clustered around similar heights, but the largest soliton was outstanding, with an amplitude significantly larger than all other solitons. The presence of a clearly outstanding soliton in the spectrum was found to be an indicator pointing towards the enhanced probability of the occurrence of a rogue wave in the time series. Similarly, when the discrete spectrum appears as a cluster of solitons without the presence of a clearly outstanding soliton, the presence of a rogue wave in the observed time series is unlikely. These results suggest that soliton-like and nonlinear processes substantially contribute to the enhanced occurrence of rogue waves off Norderney. %0 journal article %@ 0022-3670 %A Teutsch, I., Weisse, R. %D 2023 %J Journal of Physical Oceanography %N 1 %P 269-286 %R doi:10.1175/JPO-D-22-0059.1 %T Rogue Waves in the Southern North Sea-The Role of Modulational Instability %U https://doi.org/10.1175/JPO-D-22-0059.1 1 %X The role of the modulational instability for rogue wave generation in the ocean is still under debate. We investigated a continuous data set, consisting of buoy and radar wave elevation data of different frequency resolutions, from eight measurement stations in the southern North Sea. For periods with rogue waves, we evaluated the presence of conditions for the modulational instability to work, that is, a narrow-banded wave spectrum in both, frequency and angular direction. We found rogue waves exceeding twice the significant wave height indeed to occur at slightly lower frequency bandwidths than usual. For rogue waves that are defined only by high crests, this was, however, not the case. The results were dependent on the measurement frequency. The directional spreading of the buoy spectra yielded no information on the presence of a rogue wave. In general, all spectra estimated from the data set were found to be broad in frequency and angular direction, while the Benjamin–Feir index yielded no indication on a high nonlinearity of the sea states. These are unfavorable conditions for the evolution of a rogue wave through modulational instability. We conclude that the modulational instability did not play a substantial role in the formation of the rogue waves identified in our data set from the southern North Sea. %0 journal article %@ 0078-3234 %A Hagemann, Stefan, Stacke, Tobias %D 2023 %J Oceanologia %N 1 %P 230-248 %R doi:10.1016/j.oceano.2022.07.003 %T Complementing ERA5 and E-OBS with high-resolution river discharge over Europe %U https://doi.org/10.1016/j.oceano.2022.07.003 1 %X The 0.5° resolution of many global observational or quasi-observational datasets is not sufficient for the evaluation of current state-of-the-art regional climate models or the forcing of ocean model simulations over Europe. While higher resolved products are available for meteorological data, e.g. ERA5 reanalysis and the E-OBS vs 22 (EOBS22) datasets, they lack crucial information at the land-ocean boundary. ERA5 is frequently used to force regional climate models (RCMs) or ocean models and both datasets are commonly used as reference datasets for the evaluation of RCMs. Therefore, we extended both datasets with high-resolution river discharge for the period 1979–2018. On the one hand, our discharge data close the water cycle at the land-ocean interface so that the discharges can be used as lateral freshwater input for ocean models applied in the European region. On the other hand, the data can be used to identify trends in discharge that are induced by recent climate change as ERA5 and EOBS22 are rather independent datasets. The experimental setup to generate the discharges was chosen in a way that it could be easily adapted in a climate or Earth system modelling framework. Consequently, the recently developed 5 Min. horizontal resolution version of the hydrological discharge (HD) model was used to simulate discharge. It has already been applied in multiple climate modelling studies and is coupled within several global and regional Earth system models. As the HD model currently does not regard direct human impacts of the river runoff, it is well suited to investigate climate change-related discharge trends. In order to calculate the necessary gridded input fields for the HD model from ERA5 and EOBS22 data, we used the HydroPy global hydrological model. For both experiments, we found that the general behavior of discharge is captured well for many European rivers, which is consistent to earlier results. For the EOBS22 based discharges, a widespread low bias in simulated discharge occurs, which is likely caused by the missing undercatch correction in the underlying precipitation data. The analysis of trends over Southeastern Europe was hampered by missing data in EOBS22 after 2004. Using both experiments, we identified consistent trend patterns in various discharge statistics, with increases in low flow characteristics over Northern Europe and general drying trends over Central and Southern Europe. In summary, we introduced an experimental setup that is useful to generate high-resolution river runoff data consistent with the meteorological forcing for historical periods and future scenarios from any climate model data instead of having to rely on observed time series. %0 journal article %@ 0078-3234 %A Porz, L., Zhang, W., Schrum, C. %D 2023 %J Oceanologia %N 1 %P 182-193 %R doi:10.1016/j.oceano.2022.03.005 %T Natural and anthropogenic influences on the development of mud depocenters in the southwestern Baltic Sea %U https://doi.org/10.1016/j.oceano.2022.03.005 1 %X The morphological evolution of two mud depocenters in the southwestern Baltic Sea is investigated by comparison of numerical model results to geological and oceanographic data. The pathways of dense currents during episodic dense-water inflows from the North Sea are shown to correspond to current pathways inferred from contouritic depositional geometries in the flow-confining channels within the study area. A favorable comparison of model results to published current speed observations shows that the mesoscale dynamics of individual inflow events are reproduced by the model, indicating that external forcing and basin geometry rather than internal dynamics control the mesoscale dynamics of inflow events. The bottom current directions during inflows show high stability in the flow-confining channels and explain the contouritic depositional geometries. Asymmetric depositional features in the channels are qualitatively reproduced in the model. Bottom currents are less stable in areas without contouritic features, possibly resulting in an overall diffusive effect on sediment distribution in those areas. In a simulation of resuspension by bottom-contacting fishing gear, inter-basin sediment transport is increased by 4–30%, depending on the area, compared to the case of natural hydrodynamic resuspension. The model predicts an increased winnowing of the finest sediment fraction due to bottom trawling, leading to an overall coarsening-to-fining trend in the direction of net sediment transport. The results show that rather than hemi-pelagic background sedimentation, episodic events with high bottom current velocities as well as bottom-trawling induced resuspension are responsible for the present-day and future morphological configuration of the mud depocenters in the southwestern Baltic Sea. %0 journal article %@ 0078-3234 %A von Storch, H. %D 2023 %J Oceanologia %N 1 %P 44-49 %R doi:10.1016/j.oceano.2021.08.005 %T Perceptions of an endangered Baltic Sea %U https://doi.org/10.1016/j.oceano.2021.08.005 1 %X The results are not representative – neither for the separate surveys, nor for the selection of the sites of surveying. However, when taken all surveys together, the emergence of consistent perceptions may be considered evidence for a general attitude among students and young scholars in the Baltic regions. However, differences between groups – in terms of nationality, seniority and discipline - may be related to sampling randomness. %0 journal article %@ 1365-2400 %A Kühn, B., Kempf, A., Brunel, T., Cole, H., Mathis, M., Sys, K., Trijoulet, V., Vermard, Y., Taylor, M. %D 2023 %J Fisheries Management and Ecology %N 4 %P 360-377 %R doi:10.1111/fme.12629 %T Adding to the mix – challenges of mixed fisheries management in the North Sea under climate change and technical interactions %U https://doi.org/10.1111/fme.12629 4 %X Technical interactions (multiple fleets fishing multiple species with various gears, as either target or bycatch), bycatch regulations through a landing obligation, and biological and economic effects of climate change, affecting fisheries yield and profits, provide a challenge for demersal mixed fisheries of the North Sea. A multi-stock, multi-fleet, bioeconomic model was used to understand management options under these combined influences. Scenarios considered climate change effects on recruitment of three main gadoid stocks (cod – Gadus morhua, saithe – Pollachius virens, whiting – Merlangius merlangus), possible future developments of fuel and fish prices, and strict implementation of a landing obligation. The latter leads to decreased yield and profits in the short term due to increased choke effects, mainly of North Sea cod, being influenced by climate-induced productivity changes. Allowing fishing above FMSY, but within sustainable limits, or limiting year-to-year quota changes, could help buffer initial losses at the expense of decreased profits in the mid- to long-term. Economic performance of individual fleets was linked to their main target's stock status, cost structure, and fuel and fish prices. The results highlight a need to consider both biological and economic consequences of climate change in the management of mixed fisheries. %0 journal article %@ 2073-4433 %A Schwarzkopf, D.A., Petrik, R., Hahn, J., Ntziachristos, L., Matthias, V., Quante, M. %D 2023 %J Atmosphere %N 5 %P 879 %R doi:10.3390/atmos14050879 %T Future Ship Emission Scenarios with a Focus on Ammonia Fuel %U https://doi.org/10.3390/atmos14050879 5 %X Current efforts by the International Maritime Organization (IMO) to decarbonize the shipping sector have gained momentum, although the exact path to achieve this goal is currently unclear. However, it can be safely assumed that alternative cleaner and zero-carbon fuels will be key components in the strategy. In this work, three ship emission scenarios for 2025, 2040, and 2050 were developed that cover the area of the North and Baltic Seas. They aim at a fundamental transition in the usage of marine fuels towards ammonia as the mainly used fuel in 2050, via an intermediate step in 2040 with liquefied natural gas as the main fuel. Additionally, expected trends and developments for the shipping sector were implemented, i.e., a fleet growth by vessel size and number. Efficiency improvements were included that are in accordance with the Energy Efficiency Design Index of the IMO. The scenarios were created using a novel method based on modifications to a virtual shipping fleet. The vessels in this fleet were subject to decommission and renewal cycles that adapt them to the scenario’s target year. Emissions for this renewed shipping fleet were calculated with the Modular Ship Emission Modeling System (MoSES). With respect to ammonia engine technology, two cases were considered. The first case deals with compression ignition engines and marine gas oil as pilot fuel, while the second case treats spark ignition engines and hydrogen as the pilot fuel. The first case is considered more feasible until 2050. Reductions with the first case in 2050 compared to 2015 were 40% for CO2 emissions. However, CO2 equivalents were only reduced by 22%, with the difference mainly resulting from increased N2O emissions. NOX emissions were reduced by 39%, and different PM components and SO2 were between 73% and 84% for the same target year. The estimated NH3 slip from ammonia-fueled ships in the North and Baltic Seas was calculated to be 930 Gg in 2050. For the second ammonia engine technology that is considered more advanced, emission reductions were generally stronger and ammonia emissions smaller. %0 journal article %@ 1758-678X %A Petzold, J., Hawxwell, T., Jantke, K., Gonçalves Gresse, E., Mirbach, C., Ajibade, I., Bhadwal, S., Bowen, K., Fischer, A.P., Joe, E.T., Kirchhoff, C.J., Mach, K.J., Reckien, D., Segnon, A.C., Singh, C., Ulibarri, N., Campbell, D., Cremin, E., Färber, L., Hegde, G., Jeong, J., Nunbogu, A.M., Pradhan, H.K., Schröder, L.S., Shah, M.A.R., Reese, P., Sultana, F., Tello, C., Xu, J., The Global Adaptation Mapping Initiative Team, Garschagen, M. %D 2023 %J Nature Climate Change %P 1250-1257 %R doi:doi.org/10.1038/s41558-023-01824-z %T A global assessment of actors and their roles in climate change adaptation %U https://doi.org/doi.org/10.1038/s41558-023-01824-z %X An assessment of the global progress in climate change adaptation is urgently needed. Despite a rising awareness that adaptation should involve diverse societal actors and a shared sense of responsibility, little is known about the types of actors, such as state and non-state, and their roles in different types of adaptation responses as well as in different regions. Based on a large n-structured analysis of case studies, we show that, although individuals or households are the most prominent actors implementing adaptation, they are the least involved in institutional responses, particularly in the global south. Governments are most often involved in planning and civil society in coordinating responses. Adaptation of individuals or households is documented especially in rural areas, and governments in urban areas. Overall, understanding of institutional, multi-actor and transformational adaptation is still limited. These findings contribute to debates around ‘social contracts’ for adaptation, that is, an agreement on the distribution of roles and responsibilities, and inform future adaptation governance. %0 journal article %@ 2752-0706 %A Ciliberti, S.A., Alvarez Fanjul, E., Pearlman, J., Wilmer-Becker, K., Bahurel, P., Ardhuin, F., Arnaud, A., Bell, M., Berthou, S., Bertino, L., Capet, A., Chassignet, E., Ciavatta, S., Cirano, M., Clementi, E., Cossarini, G., Coro, G., Corney, S., Davidson, F., Drevillon, M., Drillet, Y., Dussurget, R., El Serafy, G., Fennel, K., Garcia Sotillo, M., Heimbach, P., Hernandez, F., Hogan, P., Hoteit, I., Joseph, S., Josey, S., Le Traon, P.Y., Libralato, S., Mancini, M., Matte, P., Melet, A., Miyazawa, Y., Moore, A.M., Novellino, A., Porter, A., Regan, H., Romero, L., Schiller, A., Siddorn, J., Staneva, J., Thomas-Courcoux, C., Tonani, M., Garcia-Valdecasas, J.M., Veitch, J., von Schuckmann, K., Wan, L., Wilkin, J., Zufic, R. %D 2023 %J State of the Planet %R doi:10.5194/sp-1-osr7-2-2023 %T Evaluation of operational ocean forecasting systems from the perspective of the users and the experts %U https://doi.org/10.5194/sp-1-osr7-2-2023 %X %0 journal article %@ 2296-7745 %A Kossack, J., Mathis, M., Daewel, U., Zhang, Y.J., Schrum, C. %D 2023 %J Frontiers in Marine Science %P 1206062 %R doi:10.3389/fmars.2023.1206062 %T Barotropic and baroclinic tides increase primary production on the North-West European Shelf %U https://doi.org/10.3389/fmars.2023.1206062 %X High biological productivity and the efficient export of carbon-enriched subsurface waters to the open ocean via the continental shelf pump mechanism make mid-latitude continental shelves like the northwest European shelf (NWES) significant sinks for atmospheric CO2. Tidal forcing, as one of the regionally dominant physical forcing mechanisms, regulates the mixing-stratification status of the water column that acts as a major control for biological productivity on the NWES. Because of the complexity of the shelf system and the spatial heterogeneity of tidal impacts, there still are large knowledge gaps on the role of tides for the magnitude and variability of biological carbon fixation on the NWES. In our study, we utilize the flexible cross-scale modeling capabilities of the novel coupled hydrodynamic–biogeochemical modeling system SCHISM–ECOSMO to quantify the tidal impacts on primary production on the NWES. We assess the impact of both the barotropic tide and the kilometrical-scale internal tide field explicitly resolved in this study by comparing simulated hindcasts with and without tidal forcing. Our results suggest that tidal forcing increases biological productivity on the NWES and that around 16% (14.47 Mt C) of annual mean primary production on the shelf is related to tidal forcing. Vertical mixing of nutrients by the barotropic tide particularly invigorates primary production in tidal frontal regions, whereas resuspension and mixing of particulate organic matter by tides locally hinders primary production in shallow permanently mixed regions. The tidal impact on primary production is generally low in deep central and outer shelf areas except for the southwestern Celtic Sea, where tidal forcing substantially increases annual mean primary production by 25% (1.53 Mt C). Tide-generated vertical mixing of nutrients across the pycnocline, largely attributed to the internal tide field, explains one-fifth of the tidal response of summer NPP in the southwestern Celtic Sea. Our results therefore suggest that the tidal NPP response in the southwestern Celtic Sea is caused by a combination of processes likely including tide-induced lateral on-shelf transport of nutrients. The tidally enhanced turbulent mixing of nutrients fuels new production in the seasonally stratified parts of the NWES, which may impact the air–sea CO2 exchange on the shelf. %0 journal article %@ 2296-7745 %A El Serafy, G., Mészáros, L., Fernández, V., Capet, A., She, J., Sotillo, M.G., Melet, A., Legrand, S., Mourre, B., Campuzano, F., Federico, I., Guarnieri, A., Rubio, A., Dabrowski, T., Umgiesser, G., Staneva, J., Ursella, L., Pairaud, I., Bruschi, A., Frigstad, H., Baetens, K., Creach, V., Charria, G., Alvarez Fanjul, E. %D 2023 %J Frontiers in Marine Science %P 1177615 %R doi:10.3389/fmars.2023.1177615 %T EuroGOOS roadmap for operational coastal downstream services %U https://doi.org/10.3389/fmars.2023.1177615 %X The EuroGOOS Coastal working group examines the entire coastal value chain from coastal observations to services for coastal users. The main objective of the working group is to review the status quo, identify gaps and future steps needed to secure and improve the sustainability of the European coastal service provision. Within this framework, our white paper defines a EuroGOOS roadmap for sustained “community coastal downstream service” provision, provided by a broad EuroGOOS community with focus on the national and local scale services. After defining the coastal services in this context, we describe the main components of coastal service provision and explore community benefits and requirements through sectoral examples (aquaculture, coastal tourism, renewable energy, port, cross-sectoral) together with the main challenges and barriers to user uptake. Technology integration challenges are outlined with respect to multiparameter observations, multi-platform observations, the land-coast-ocean continuum, and multidisciplinary data integration. Finally, the technological, financial, and institutional sustainability of coastal observing and coastal service provision are discussed. The paper gives special attention to the delineation of upstream and downstream services, public-private partnerships and the important role of Copernicus in better covering the coastal zone. Therefore, our white paper is a policy and practice review providing a comprehensive overview, in-depth discussion and actionable recommendations (according to key short-term or medium-term priorities) on the envisaged elements of a roadmap for sustained coastal service provision. EuroGOOS, as an entity that unites European national operational oceanography centres, research institutes and scientists across various domains within the broader field of operational oceanography, offers to be the engine and intermediary for the knowledge transfer and communication of experiences, best practices and information, not only amongst its members, but also amongst the different (research) infrastructures, institutes and agencies that have interests in coastal oceanography in Europe. %0 journal article %@ 1400-0350 %A Jordan, P., Döring, M., Fröhle, P., Ratter, B.M.W. %D 2023 %J Journal of Coastal Conservation %P 2 %R doi:10.1007/s11852-022-00921-z %T Exploring past and present dynamics of coastal protection as possible signposts for the future? %U https://doi.org/10.1007/s11852-022-00921-z %X Coastal protection comprises shoreline preservation and stabilisation as well as flood protection. Besides these technical aspects, coastal protection also represents a genuine social endeavour. Within this interplay of technical and social dimensions, planning and acting for the safety of people and assets along the coastline has become increasingly difficult for the responsible authorities. Within this context, Nature-based Solutions (NbS) for coastal protection offer a promising addition to and adaptation for existing protection measures such as dikes, sea walls or groynes. They bear the potential to adapt to shifting boundary conditions caused by climate change and cater the growing social call for sustainable solutions that benefit water, nature and people alike. This paper analyses, how NbS can fit into the entangled and historically grown system of coastal protection. As a paradigmatic example, the German islands of Amrum and Föhr were chosen. To contextualise the topic, a brief recap of the formation of these North Frisian Islands and their social history regarding coastal protection is given. This will be followed by a review of the relevant literature on the development of coastal protection on the two islands including its historical development. Using the theory of Social Representations (SRs), these historical insights are analytically contrasted with a synchronic snapshot gained from stakeholder interviews about the assessment of protective measures, and their anticipated future development with regard to the possible feasibility and implementation of NbS. This analysis reveals that, historically and synchronically seen, coastal protection on both islands is rather characterised by a dynamic rationale and the constant testing of and experimenting with different measures and concepts. However, well-established measures like diking or the construction of brushwood groynes for foreland creation are not being questioned while new approaches running against this rationale such as NbS are in many cases initially met with scepticism and doubt. Out of this follows that past and present dynamics in coastal protection play a vital role in planning. Hence, the implementation of NbS as signposts for the future requires an integrated and balanced interdisciplinary approach that considers the socio-technical dimensions of coastal protection for future coastal adaptation. %0 journal article %@ 2296-6463 %A von Storch, H. %D 2023 %J Frontiers in Earth Science %P 1259629 %R doi:doi.org/10.3389/feart.2023.1259629 %T Editorial: Modelling; simulating and forecasting regional climate and weather Volume 2 %U https://doi.org/doi.org/10.3389/feart.2023.1259629 %X However, the regional and local scales matter in terms of the impact of climate and weather on people and ecosystems. Therefore, the scientific development in the last years was mostly in two directions–towards global Earth system models, and towards the description of regional and local dynamics, and more and more so on the regional and local impact of climate and climate change. The present Research Topic deals with the latter. %0 journal article %@ 0964-5691 %A Tafon, R., Armoskaite, A., Gee, K., Gilek, M., Ikauniece, A., Saunders, F. %D 2023 %J Ocean and Coastal Management %P 106681 %R doi:10.1016/j.ocecoaman.2023.106681 %T Mainstreaming coastally just and equitable marine spatial planning: Planner and stakeholder experiences and perspectives on participation in Latvia %U https://doi.org/10.1016/j.ocecoaman.2023.106681 %X Community participation and influence are vitally important for meeting the multidimensional sustainability aims of marine spatial planning (MSP) and more specifically for procedural and distributive justice. While participation has received substantial research interest, we identify a need to: 1) develop equity-based principles for coastal community participation that can be used to assess and reform MSP practices; 2) generate rich empirical accounts of coastal community participation and representation linked to real-world MSP practices. Here we present the results of a study that synthesizes critical MSP and blue justice scholarship to develop principles and indicators of coastally equitable and just planning. Drawing on interviews with planners and stakeholders and analysis of planning and legal documents, these principles are used to assess participatory processes linked to Latvian MSP practices in the period 2015 to 2019. Our analysis shows that equitable and just MSP needs to be based on participation that is timely, inclusive, supportive & localized, collaborative, methodical and impactful. When applied to the Latvian case these six principles provide a comprehensive and versatile heuristic approach to assess participation in MSP. In the context of Latvian MSP practices, we revealed a fundamental challenge of maintaining inclusive and localized participation throughout the full planning cycle. To counteract the successive narrowing/hardening of participatory space our results indicate a need for continuously promoting diversity of voices and perspectives, opportunities for collaborative sense making, visioning and critique. This will help to bridge diverse MSP divides (e.g., between land and sea, between local, national, and global values and priorities, between science and local knowledge, and between blue growth, conservation, and justice goals). If applied more generally in research and as part of MSP evaluation an equity-based approach can promote the mainstreaming of coastally just and equitable MSP practices. Finally, considering contextual factors (e.g., history, culture, power, legislation) that shape participation and representation is crucial when applying the equity principles to a particular MSP setting to acknowledge and accommodate its particular characteristics and challenges. %0 journal article %@ 2752-0706 %A Gramcianinov, C.B., Staneva, J., Souza, C.R.G., Linhares, P., de Camargo, R., da Silva Dias, P.L. %D 2023 %J State of the Planet %R doi:10.5194/sp-1-osr7-12-2023 %T Recent changes in extreme wave events in the south-western South Atlantic %U https://doi.org/10.5194/sp-1-osr7-12-2023 %X Over the past decades, the South Atlantic Ocean has experienced several changes, including a reported increase in coastal erosion and floods. This study aims to investigate the recent changes in the extreme wave events over the south-western South Atlantic (SWSA) – which hosts the most economically important harbours in South America, high oil and gas production demands, and rich biodiversity. This investigation considers not only the occurrence of extreme wave events but also extreme wave indicators that characterise the potential wave impact on offshore and coastal areas. Extreme wave events are obtained using the averaged monthly 95th percentile of significant wave height (Hs) from 1993 to 2021, combining the CMEMS global wave reanalysis and near-real-time products. Annual and seasonal statistics are derived to analyse mean and extreme wave climate and trends in the study region, focusing on Hs, peak period, and wave power. The analysis gives an overview of the wave climate in the study domain, including a discussion about seasonal differences. For a more direct application to future risk assessment and management, we perform an analysis considering the regional monitoring and warning system division established by the Brazilian Navy. We used a coastal hazard database that covers a portion of the coast to investigate how the trends given by the CMEMS wave products may impact the coastal zone. Our findings showed significant changes in the SWSA mainly associated with an increase in mean values of Hs, wave period, and consequently the wave power. Narrowing down to the coastal impact, we found an increase in the number of coastal hazards in the State of São Paulo associated with waves, which agrees with the increase in the number of extreme wave events in the adjacent ocean sector. However, the increased number of coastal events is also driven by local factors. %0 journal article %@ 1616-7341 %A Jacob, B., Dolch, T., Wurpts, A., Staneva, J. %D 2023 %J Ocean Dynamics %P 699-727 %R doi:10.1007/s10236-023-01577-5 %T Evaluation of seagrass as a nature-based solution for coastal protection in the German Wadden Sea %U https://doi.org/10.1007/s10236-023-01577-5 %X Global climate change increases the overall risks for coastal flooding and erosion. Meanwhile, nature-based solutions (NbS) are increasingly becoming a focus of coastal protection measures to improve the climate adaptability. In this study, the present and potential future role of seagrass in coastal risk reduction strategies were explored for the highly energetic Wadden Sea area of the German Bight. The methodology in this study combined seagrass coverage data (Zostera marina and Zostera noltei) obtained by field surveys and what-if scenario simulations using the SCHISM unstructured grid model framework, coupling hydrodynamics, waves, sediments, and a seagrass module. The results suggest that the introduction of seagrass meadows locally can reduce both current velocities and significant wave heights in the order of up to 30 in the deeper areas and above 90 in the shallow areas. Reduction in bottom shear stress of a similar relative magnitude significantly reduced sediment mobilisation on the order of 2 g/L in the 95th quantile of bottom layer sediment concentrations. Effectively altering hydromorphodynamic conditions favouring sediment accumulation, seagrass expansion could help tidal flats height growths to keep up with SLR, thus further maintaining the bathymetry-induced tidal dampening and lowering flooding and erosion risks as well the amount of energy at dike infrastructure. The accumulated effect of seagrass under calm weather conditions is considered more important than the increased attenuation in absolute values it provides during extreme conditions. The overall conclusion is that seagrass expansion could be a useful addition to engineered coastal protection measures. %0 journal article %@ 1748-9326 %A Essell, H., Krusic, P., Esper, J., Wagner, S., Braconnot, P., Jungclaus, J., Muschitiello, F., Oppenheimer, C., Büntgen, U. %D 2023 %J Environmental Research Letters %N 11 %P 114022 %R doi:10.1088/1748-9326/ad0065 %T A frequency-optimised temperature record for the Holocene %U https://doi.org/10.1088/1748-9326/ad0065 11 %X Existing global mean surface temperature reconstructions for the Holocene lack high-frequency variability that is essential for contextualising recent trends and extremes in the Earth's climate system. Here, we isolate and recombine archive-specific climate signals to generate a frequency-optimised record of interannual to multi-millennial temperature changes for the past 12 000 years. Average temperatures before ∼8000 years BP and after ∼4000 years BP were 0.26 (±2.84) °C and 0.07 (±2.11) °C cooler than the long-term mean (0–12 000 years BP), while the Holocene Climate Optimum ∼7000–4000 years BP was 0.40 (±1.86) °C warmer. Biased towards Northern Hemisphere summer temperatures, our multi-proxy record captures the spectral properties of transient Earth system model simulations for the same spatial and season domain. The new frequency-optimised trajectory emphasises the importance and complex interplay of natural climate forcing factors throughout the Holocene, with an approximation of the full range of past temperature changes providing novel insights for policymakers addressing the risks of recent anthropogenic warming. %0 journal article %@ 2296-7745 %A Breckwoldt, A., Ratter, B., Wang, W.C., von Storch, H. %D 2023 %J Frontiers in Marine Science %P 1334086 %R doi:10.3389/fmars.2023.1334086 %T Editorial: Fishing for human perceptions in coastal and island marine resource use systems; volume II %U https://doi.org/10.3389/fmars.2023.1334086 %X This Research Topic is the second volume or Relaunch of “Fishing for human perceptions in coastal and island marine resource use systems”, which can be found here. As human perceptions, decision-making and (pro-) environmental behaviour are closely connected, there continues to be an increasing interest for research evolving around perception studies, and how their use and value in academia, research and decision-making can be improved by stronger multilateral acknowledgement and tailored integration. %0 journal article %@ 1616-7341 %A Lin, L., von Storch, H., Chen, X., Jiang, W., Tang, S. %D 2023 %J Ocean Dynamics %P 793-806 %R doi:10.1007/s10236-023-01583-7 %T Link between the internal variability and the baroclinic instability in the Bohai and Yellow Sea %U https://doi.org/10.1007/s10236-023-01583-7 %X A regional ocean ensemble simulation with slightly different initial conditions demonstrates that internal variability is formed (not only) in the Bohai and Yellow Sea. In this paper, we analyze the relationship between the internal variability and the baroclinic instability, (represented by the Eady predicted theoretical diffusivity Kt; the larger the Kt, the stronger the baroclinic instability level). In the ensemble, with tidal forcing, the spatial correlation between the Eady predicted theoretical diffusivity Kt and the internal variability amounts to 0.80. Also, the time evolution trends of baroclinic instability and internal variability are similar. Based on this evidence, baroclinic instability may be a significant driver for internal variability. This hypothesis is validated using an additional ensemble of simulations, which is identical to the first ensemble, but this time, the tides are inactivated. This modification leads to an increase in internal variability, combined with the strengthening of baroclinic instability. In addition, the baroclinic instability level and internal variability variation co-vary consistently when comparing summer and winter seasons, both with and without tides. Our interpretation is that a stronger baroclinic instability causes more potential energy to be transformed into kinetic energy, allowing the unforced disturbances to grow. %0 journal article %@ 1814-9324 %A Malmierca-Vallet, I., Sime, L.C., Abe-Ouchi, A., Born, A., Bouttes, N., Ditlevsen, P., Erb, M.P., Feulner, G., Gowan, E.J., Gregoire, L., Guo, C., Harrison, S.P., Andres, H., Kageyama, M., Klockmann, M., Lambert, F., LeGrande, A.N., Merkel, U., Nazarenko, L.S., Nisancioglu, K.H., Oliver, K., Otto-Bliesner, B., Peltier, W.R., Prange, M., Rehfeld, K., Robinson, A.J., Tarasov, L., Valdes, P.J., Vettoretti, G., Weitzel, N., Zhang, Q., Zhang, X. %D 2023 %J Climate of the Past %N 5 %P 915-942 %R doi:10.5194/cp-19-915-2023 %T Dansgaard–Oeschger events in climate models: review and baseline Marine Isotope Stage 3 (MIS3) protocol %U https://doi.org/10.5194/cp-19-915-2023 5 %X Dansgaard–Oeschger (D–O) events, millennial-scale climate oscillations between stadial and interstadial conditions (of up to 10–15 ∘C in amplitude at high northern latitudes), occurred throughout the Marine Isotope Stage 3 (MIS3; 27.8–59.4 ka) period. The climate modelling community up to now has not been able to answer the question of whether our climate models are too stable to simulate D–O events. To address this, this paper lays the ground-work for a MIS3 D–O protocol for general circulation models which are used in the International Panel for Climate Change (IPCC) assessments. We review the following: D–O terminology, community progress on simulating D–O events in these IPCC-class models (processes and published examples), and evidence about the boundary conditions under which D–O events occur. We find that no model exhibits D–O-like behaviour under pre-industrial conditions. Some, but not all, models exhibit D–O-like oscillations under MIS3 and/or full glacial conditions. Greenhouse gases and ice sheet configurations are crucial. However most models have not run simulations of long enough duration to be sure which models show D–O-like behaviour, under either MIS3 or full glacial states. We propose a MIS3 baseline protocol at 34 ka, which features low obliquity values, medium to low MIS3 greenhouse gas values, and the intermediate ice sheet configuration, which our review suggests are most conducive to D–O-like behaviour in models. We also provide a protocol for a second freshwater (Heinrich-event-preconditioned) experiment, since previous work suggests that this variant may be helpful in preconditioning a state in models which is conducive to D–O events. This review provides modelling groups investigating MIS3 D–O oscillations with a common framework, which is aimed at (1) maximising the chance of the occurrence of D–O-like events in the simulations, (2) allowing more precise model–data evaluation, and (3) providing an adequate central point for modellers to explore model stability. %0 journal article %@ 2366-7451 %A von Brandis, A., Centurelli, G., Schmidt, J., Vollmer, L., Djath, B., Dörenkämper, M. %D 2023 %J Wind Energy Science %N 4 %P 589-606 %R doi:10.5194/wes-8-589-2023 %T An investigation of spatial wind direction variability and its consideration in engineering models %U https://doi.org/10.5194/wes-8-589-2023 4 %X We propose that considering mesoscale wind direction changes in the computation of wind farm cluster wakes could reduce the uncertainty of engineering wake modeling tools. The relevance of mesoscale wind direction changes is investigated using a wind climatology of the German Bight area covering 30 years, derived from the New European Wind Atlas (NEWA). Furthermore, we present a new solution for engineering modeling tools that accounts for the effect of such changes on the propagation of cluster wakes. The mesoscale wind direction changes relevant to the operation of wind farm clusters in the German Bight are found to exceed 11∘ in 50 % of all cases. Particularly in the lower partial load range, which is associated with strong wake formation, the wind direction changes are the most pronounced, with quartiles reaching up to 20∘. Especially on a horizontal scale of several tens of kilometers to 100 km, wind direction changes are relevant. Both the temporal and spatial scales at which large wind direction changes occur depend on the presence of synoptic pressure systems. Furthermore, atmospheric conditions which promote far-reaching wakes were found to align with a strong turning in 14.6 % of the cases. In order to capture these mesoscale wind direction changes in engineering model tools, a wake propagation model was implemented in the Fraunhofer IWES wind farm and wake modeling software flappy (Farm Layout Program in Python). The propagation model derives streamlines from the horizontal velocity field and forces the single turbine wakes along these streamlines. This model has been qualitatively evaluated by simulating the flow around wind farm clusters in the German Bight with data from the mesoscale atlas of the NEWA and comparing the results to synthetic aperture radar (SAR) measurements for selected situations. The comparison reveals that the flow patterns are in good agreement if the underlying mesoscale data capture the velocity field well. For such cases, the new model provides an improvement compared to the baseline approach of engineering models, which assumes a straight-line propagation of wakes. The streamline and the baseline models have been further compared in terms of their quantitative effect on the energy yield. Simulating two neighboring wind farm clusters over a time period of 10 years, it is found that there are no significant differences across the models when computing the total energy yield of both clusters. However, extracting the wake effect of one cluster on the other, the two models show a difference of about 1 %. Even greater differences are commonly observed when comparing single situations. Therefore, we claim that the model has the potential to reduce uncertainty in applications such as site assessment and short-term power forecasting. %0 journal article %@ 0941-2948 %A Cañadillas, B., Wang, S., Ahlert, Y., Djath, B., Barekzai, M., Foreman, R., Lampert, A. %D 2023 %J Meteorologische Zeitschrift %N 3 %P 207-228 %R doi:10.1127/metz/2022/1166 %T Coastal horizontal wind speed gradients in the North Sea based on observations and ERA5 reanalysis data %U https://doi.org/10.1127/metz/2022/1166 3 %X The transition from land to sea affects the wind field in coastal regions. From the perspective of near-coastal offshore wind farms, the coastal transition complicates the task of energy resource assessment by, for example, introducing non-homogeneity into the free wind field. To help elucidate the matter, we quantify the average horizontal wind speed gradients at progressively increasing distances from the German coast using two years of hourly ERA5 reanalysis data, and further describe the dependence of wind speed gradients on the measurement height, atmospheric stability, and season. A vertical wind lidar located on Norderney Island near the German mainland acts as our observational reference for the ERA5 data, where a good agreement ( R 2 = 0 . 9 3 $R^2 =\nobreak 0.93$ ) is found despite the relatively coarse ERA5 data resolution. Interestingly, the comparison of lidar data with the higher-resolution Weather Research and Forecasting (WRF) mesoscale model yields good but relatively weaker agreement ( R 2 = 0 . 8 5 $R^2 =\nobreak 0.85$ ). The ERA5 data reveal that, for flow over the North Sea originating from the German mainland from the south, the wind speed at 10 m (110 m) above sea level increases by 30 % (20 %) some 80 km from the coast on average, and by 5 % at larger heights. An increased stratification increases the horizontal wind speed gradient at 10 m above sea level but decreases it at 110 m. Case studies using satellite and flight measurements are first analyzed to help reveal some of the underlying mechanisms governing horizontal wind speed gradients, including cases of decreasing wind speed with increasing distance from the coast, in which stable flow of warm air over the colder sea leads to an overall deceleration of the flow. The accuracy of offshore resource assessment appears to profit from utilising the horizontal wind speed gradient information contained in ERA5 reanalysis data. %0 journal article %@ 1616-7341 %A Gramcianinov, C.B., Staneva, J., de Camargo, R., da Silva Dias, P.L. %D 2023 %J Ocean Dynamics %P 663-678 %R doi:10.1007/s10236-023-01575-7 %T Changes in extreme wave events in the southwestern South Atlantic Ocean %U https://doi.org/10.1007/s10236-023-01575-7 %X The southwestern South Atlantic (SWSA) has faced several extreme events that caused coastal and ocean hazards associated with high waves. This study aimed to investigate the extreme wave climate trends in the SWSA using percentile- and storm-based approaches to determine potential coastal impacts. Changes in extreme wave event characteristics were evaluated through distribution maps and directional density distributions. Our results showed an overall increase in the 95th-percentile of the significant wave height (Hs), mostly in the northern and southern portions of the domain. There was a general increase in the area affected by the events and in their lifetimes in the austral summer. In contrast, winter events had higher maximum intensities, which were not homogeneous throughout the domain. Changes in the wave power direction affected most of the analysed locations, showing a clockwise shift of summer events and a large directional spread of events from the southern quadrant (SW–SE). These changes were related to the southwards shift of the subtropical branch of the storm track, reflecting increased cyclonic activity at 30∘ S (summer) and 45∘ S (winter). These storm track shifts allowed the development of large fetches on the southern edge of the domain, promoting the propagation of long waves. %0 journal article %@ 2632-2153 %A Schanz, T., Möller, K.O., Rühl, S., Greenberg, D.S. %D 2023 %J Machine Learning: Science and Technology %N 3 %P 035007 %R doi:10.1088/2632-2153/ace417 %T Robust detection of marine life with label-free image feature learning and probability calibration %U https://doi.org/10.1088/2632-2153/ace417 3 %X Advances in in situ marine life imaging have significantly increased the size and quality of available datasets, but automatic image analysis has not kept pace. Machine learning has shown promise for image processing, but its effectiveness is limited by several open challenges: the requirement for large expert-labeled training datasets, disagreement among experts, under-representation of various species and unreliable or overconfident predictions. To overcome these obstacles for automated underwater imaging, we combine and test recent developments in deep classifier networks and self-supervised feature learning. We use unlabeled images for pretraining deep neural networks to extract task-relevant image features, allowing learning algorithms to cope with scarcity in expert labels, and carefully evaluate performance in subsequent label-based tasks. Performance on rare classes is improved by applying data rebalancing together with a Bayesian correction to avoid biasing inferred in situ class frequencies. A divergence-based loss allows training on multiple, conflicting labels for the same image, leading to better estimates of uncertainty which we quantify with a novel accuracy measure. Together, these techniques can reduce the required label counts ∼100-fold while maintaining the accuracy of standard supervised training, shorten training time, cope with expert disagreement and reduce overconfidence. %0 journal article %@ 1752-0894 %A Laepple, T., Ziegler, E., Weitzel, N., Hébert, R., Ellerhoff, B., Schoch, P., Martrat, B., Bothe, O., Moreno-Chamarro, E., Chevalier, M., Herbert, A., Rehfeld, K. %D 2023 %J Nature Geoscience %P 958–966 %R doi:10.1038/s41561-023-01299-9 %T Regional but not global temperature variability underestimated by climate models at supradecadal timescales %U https://doi.org/10.1038/s41561-023-01299-9 %X Knowledge of the characteristics of natural climate variability is vital when assessing the range of plausible future climate trajectories in the next decades to centuries. The reliable detection of climate fluctuations on multidecadal to centennial timescales depends on proxy reconstructions and model simulations, as the instrumental record extends back only a few decades in most parts of the world. Systematic comparisons between model-simulated and proxy-based inferences of natural variability, however, often seem contradictory. Locally, simulated temperature variability is consistently smaller on multidecadal and longer timescales than is indicated by proxy-based reconstructions, implying that climate models or proxy interpretations might have deficiencies. In contrast, at global scales, studies found agreement between simulated and proxy reconstructed temperature variations. Here we review the evidence regarding the scale of natural temperature variability during recent millennia. We identify systematic reconstruction deficiencies that may contribute to differing local and global model–proxy agreement but conclude that they are probably insufficient to resolve such discrepancies. Instead, we argue that regional climate variations persisted for longer timescales than climate models simulating past climate states are able to reproduce. This would imply an underestimation of the regional variability on multidecadal and longer timescales and would bias climate projections and attribution studies. Thus, efforts are needed to improve the simulation of natural variability in climate models accompanied by further refining proxy-based inferences of variability. %0 journal article %@ 2624-9553 %A Heinrich, P., Hagemann, S., Weisse, R., Gaslikova, L. %D 2023 %J Frontiers in Climate %P 1227613 %R doi:10.3389/fclim.2023.1227613 %T Changes in Compound Flood Event Frequency in Northern and Central Europe under Climate Change %U https://doi.org/10.3389/fclim.2023.1227613 %X The simultaneous occurrence of increased river discharge and high coastal water levels may cause compound flooding. Compound flood events can potentially cause greater damage than the separate occurrence of the underlying extreme events, making them essential for risk assessment. Even though a general increase in the frequency and/or severity of compound flood events is assumed due to climate change, there have been very few studies conducted for larger regions of Europe. Our work, therefore, focuses on the high-resolution analysis of changes in extreme events of coastal water levels, river discharge, and their concurrent appearance at the end of this century in northern and central Europe (2070–2099). For this, we analyze downscaled data sets from two global climate models (GCMs) for the two emissions scenarios RCP2.6 and RCP8.5. First, we compare the historical runs of the downscaled GCMs to historical reconstruction data to investigate if they deliver comparable results for northern and central Europe. Then we study changes in the intensity of extreme events, their number, and the duration of extreme event seasons under climate change. Our analysis shows increases in compound flood events over the whole European domain, mostly due to the rising mean sea level. In some areas, the number of compound flood event days increases by a factor of eight at the end of the current century. This increase is concomitant with an increase in the annual compound flood event season duration. Furthermore, the sea level rise associated with a global warming of 2K will result in double the amounts of compound flood event days for nearly every European river estuary considered. %0 journal article %@ 0094-8276 %A Koul, V., Brune, S., Akimova, A., Düsterhus, A., Pieper, P., Hövel, L., Parekh, A., Schrum, C., Baehr, J. %D 2023 %J Geophysical Research Letters %N 18 %P e2023GL103975 %R doi:doi.org/10.1029/2023GL103975 %T Seasonal Prediction of Arabian Sea Marine Heatwaves %U https://doi.org/doi.org/10.1029/2023GL103975 18 %X Marine heatwaves are known to have a detrimental impact on marine ecosystems, yet predicting when and where they will occur remains a challenge. Here, using a large ensemble of initialized predictions from an Earth System Model, we demonstrate skill in predictions of summer marine heatwaves over large marine ecosystems in the Arabian Sea seven months ahead. Retrospective forecasts of summer (June to August) marine heatwaves initialized in the preceding winter (November) outperform predictions based on observed frequencies. These predictions benefit from initialization during winters of medium to strong El Niño conditions, which have an impact on marine heatwave characteristics in the Arabian Sea. Our probabilistic predictions target spatial characteristics of marine heatwaves that are specifically useful for fisheries management, as we demonstrate using an example of Indian oil sardine (Sardinella longiceps). %0 journal article %@ 2077-1312 %A Schulz-Stellenfleth, J., Blauw, A., Laakso, L., Mourre, B., She, J., Wehde, H. %D 2023 %J Journal of Marine Science and Engineering %N 9 %P 1817 %R doi:10.3390/jmse11091817 %T Fit-for-Purpose Information for Offshore Wind Farming Applications—Part-II: Gap Analysis and Recommendations %U https://doi.org/10.3390/jmse11091817 9 %X Offshore wind energy installations in coastal areas have grown massively over the last decade. This development comes with a large number of technological, environmental, economic, and scientific challenges, which need to be addressed to make the use of offshore wind energy sustainable. One important component in these optimization activities is suitable information from observations and numerical models. The purpose of this study is to analyze the gaps that exist in the present monitoring systems and their respective integration with models. This paper is the second part of two manuscripts and uses results from the first part about the requirements for different application fields. The present solutions to provide measurements for the required information products are described for several European countries with growing offshore wind operations. The gaps are then identified and discussed in different contexts, like technology evolution, trans-European monitoring and modeling initiatives, legal aspects, and cooperation between industry and science. The monitoring gaps are further quantified in terms of missing observed quantities, spatial coverage, accuracy, and continuity. Strategies to fill the gaps are discussed, and respective recommendations are provided. The study shows that there are significant information deficiencies that need to be addressed to ensure the economical and environmentally friendly growth of the offshore wind farm sector. It was also found that many of these gaps are related to insufficient information about connectivities, e.g., concerning the interactions of wind farms from different countries or the coupling between physical and biological processes. %0 journal article %@ 2077-1312 %A She, J., Blauw, A., Laakso, L., Mourre, B., Schulz-Stellenfleth, J., Wehde, H. %D 2023 %J Journal of Marine Science and Engineering %N 8 %P 1630 %R doi:10.3390/jmse11081630 %T Fit-for-Purpose Information for Offshore Wind Farming Applications Part-I: Identification of Needs and Solutions. %U https://doi.org/10.3390/jmse11081630 8 %X The rapid expansion of offshore wind farms (OWFs) in European seas is accompanied by many challenges, including efficient and safe operation and maintenance, environmental protection, and biodiversity conservation. Effective decision-making for industry and environmental agencies relies on timely, multi-disciplinary marine data to assess the current state and predict the future state of the marine system. Due to high connectivity in space (land–estuarial–coastal sea), socioeconomic (multi-sectoral and cross-board), and environmental and ecological processes in sea areas containing OWFs, marine observations should be fit for purpose in relation to multiple OWF applications. This study represents an effort to map the major observation requirements (Part-I), identify observation gaps, and recommend solutions to fill those gaps (Part-II) in order to address multi-dimension challenges for the OWF industry. In Part-I, six targeted areas are selected, including OWF operation and maintenance, protection of submarine cables, wake and lee effects, transport and security, contamination, and ecological impact assessments. For each application area, key information products are identified, and integrated modeling–monitoring solutions for generating the information products are proposed based on current state-of-the-art methods. The observation requirements for these solutions, in terms of variables and spatial and temporal sampling needs, are therefore identified. %0 journal article %@ 0142-7873 %A Garcia-Oliva, O., Hantzsche, F., Boersma, M., Wirtz, K. %D 2022 %J Journal of Plankton Research %N 2 %P 224-240 %R doi:10.1093/plankt/fbac013 %T Phytoplankton and particle size spectra indicate intense mixotrophic dinoflagellates grazing from summer to winter %U https://doi.org/10.1093/plankt/fbac013 2 %X Mixotrophic dinoflagellates (MTD) are a diverse group of organisms often responsible for the formation of harmful algal blooms. However, the development of dinoflagellate blooms and their effects on the plankton community are still not well explored. Here we relate the species succession of MTD with parallel changes of phytoplankton size spectra during periods of MTD dominance. We used FlowCAM analysis to acquire size spectra in the range 2–200 μm every one or two weeks from July to December 2007 at Helgoland Roads (Southern North Sea). Most size spectra of dinoflagellates were bimodal, whereas for other groups, e.g. diatoms and autotrophic flagellates, the spectra were unimodal, which indicates different resource use strategies of autotrophs and mixotrophs. The biomass lost in the size spectrum correlates with the potential grazing pressure of MTD. Based on size-based analysis of trophic linkages, we suggest that mixotrophy, including detritivory, drives species succession and facilitates the formation of bimodal size spectra. Bimodality in particular indicates niche differentiation through grazing of large MTD on smaller MTD. Phagotrophy of larger MTD may exceed one of the smaller MTD since larger prey was more abundant than smaller prey. Under strong light limitation, a usually overlooked refuge strategy may derive from detritivory. The critical role of trophic links of MTD as a central component of the plankton community may guide future observational and theoretical research. %0 journal article %@ 2190-4979 %A Meier, H., Kniebusch, M., Dieterich, C., Gröger, M., Zorita, E., Elmgren, R., Myrberg, K., Ahola, M. P., Bartosova, A., Bonsdorff, E., Börgel, F., Capell, R., Carlén, I., Carlund, T., Carstensen, J., Christensen, O. B., Dierschke, V., Frauen, C., Frederiksen, M., Gaget, E., Galatius, A., Haapala, J. J., Halkka, A., Hugelius, G., Hünicke, B., Jaagus, J., Jüssi, M., Käyhkö, J., Kirchner, N., Kjellström, E., Kulinski, K., Lehmann, A., Lindström, G., May, W., Miller, P. A., Mohrholz, V., Müller-Karulis, B., Pavón-Jordán, D., Quante, M., Reckermann, M., Rutgersson, A., Savchuk, O. P., Stendel, M., Tuomi, L., Viitasalo, M., Weisse, R., Zhang, W. %D 2022 %J Earth System Dynamics %N 1 %P 457-593 %R doi:10.5194/esd-13-457-2022 %T Climate change in the Baltic Sea region: a summary %U https://doi.org/10.5194/esd-13-457-2022 1 %X Based on the Baltic Earth Assessment Reports of this thematic issue in Earth System Dynamics and recent peer-reviewed literature, current knowledge of the effects of global warming on past and future changes in climate of the Baltic Sea region is summarised and assessed. The study is an update of the Second Assessment of Climate Change (BACC II) published in 2015 and focuses on the atmosphere, land, cryosphere, ocean, sediments, and the terrestrial and marine biosphere. Based on the summaries of the recent knowledge gained in palaeo-, historical, and future regional climate research, we find that the main conclusions from earlier assessments still remain valid. However, new long-term, homogenous observational records, for example, for Scandinavian glacier inventories, sea-level-driven saltwater inflows, so-called Major Baltic Inflows, and phytoplankton species distribution, and new scenario simulations with improved models, for example, for glaciers, lake ice, and marine food web, have become available. In many cases, uncertainties can now be better estimated than before because more models were included in the ensembles, especially for the Baltic Sea. With the help of coupled models, feedbacks between several components of the Earth system have been studied, and multiple driver studies were performed, e.g. projections of the food web that include fisheries, eutrophication, and climate change. New datasets and projections have led to a revised understanding of changes in some variables such as salinity. Furthermore, it has become evident that natural variability, in particular for the ocean on multidecadal timescales, is greater than previously estimated, challenging our ability to detect observed and projected changes in climate. In this context, the first palaeoclimate simulations regionalised for the Baltic Sea region are instructive. Hence, estimated uncertainties for the projections of many variables increased. In addition to the well-known influence of the North Atlantic Oscillation, it was found that also other low-frequency modes of internal variability, such as the Atlantic Multidecadal Variability, have profound effects on the climate of the Baltic Sea region. Challenges were also identified, such as the systematic discrepancy between future cloudiness trends in global and regional models and the difficulty of confidently attributing large observed changes in marine ecosystems to climate change. Finally, we compare our results with other coastal sea assessments, such as the North Sea Region Climate Change Assessment (NOSCCA), and find that the effects of climate change on the Baltic Sea differ from those on the North Sea, since Baltic Sea oceanography and ecosystems are very different from other coastal seas such as the North Sea. While the North Sea dynamics are dominated by tides, the Baltic Sea is characterised by brackish water, a perennial vertical stratification in the southern subbasins, and a seasonal sea ice cover in the northern subbasins. %0 journal article %@ 2072-4292 %A Djath, B., Schulz-Stellenfleth, J., Cañadillas, B. %D 2022 %J Remote Sensing %N 7 %P 1688 %R doi:10.3390/rs14071688 %T Study of Coastal Effects Relevant for Offshore Wind Energy Using Spaceborne Synthetic Aperture Radar (SAR) %U https://doi.org/10.3390/rs14071688 7 %X Coastal wind speed gradients relevant for offshore windfarming are analysed based on synthetic aperture radar (SAR) data. The study concentrates on situations with offshore wind directions in the German Bight using SAR scenes from the European satellites Sentinel-1A and Sentinel-1B. High resolution wind fields at 10 m height are derived from the satellite data set and respective horizontal wind speed gradients are investigated up to about 170 km offshore. The wind speed gradients are classified according to their general shape with about 60% of the cases showing an overall increase of wind speeds with growing distance from the coast. About half of the remaining cases show an overall wind speed decrease and the other half a decrease with a subsequent increase at larger distances from the coast. An empirical model is fitted to the horizontal wind speed gradients, which has three main parameters, namely, the wind speed over land, the equilibrium wind speed over sea far offshore, and a characteristic adjustment length scale. For the cases with overall wind speed increase, a mean absolute difference of about 2.6 m/s is found between wind speeds over land and wind speeds far offshore. The mean normalised wind speed increase with respect to the land conditions is estimated as 40%. In terms of wind power density at 10 m height this corresponds to an absolute average growth by 0.3 kW/m2 and a normalised increase by 160%. The distance over which the wind speed grows to 95% of the maximum wind speed shows large variations with maximum above 170 km and a mean of 67 km. The impact of the atmospheric boundary layer stability on horizontal wind speed gradients is investigated using additional information on air and sea temperature differences. The absolute SAR-derived wind speed increase offshore is usually higher in unstable situations and the respective adjustment distance is shorter. Furthermore, we have found atypical cases with a wind speed decrease offshore to be often connected to stable atmospheric conditions. A particular low-level jet (LLJ) situation is analysed in more detail using vertical wind speed profiles from a wind LIDAR system. %0 journal article %@ 0278-4343 %A Şen, O., Saçu, Ş., Erdik, T., Öztürk, İ., Stanev, E. %D 2022 %J Continental Shelf Research %P 104723 %R doi:10.1016/j.csr.2022.104723 %T Assessing the potential impacts of the Canal Istanbul on the physical oceanography of the Turkish Straits System %U https://doi.org/10.1016/j.csr.2022.104723 %X The Turkish Straits System (TSS) is a region of intense mixing between the Black Sea and the Mediterranean Sea exerting crucial control on the water & substance exchange through the Bosphorus and Dardanelles straits between these two sea basins. A waterway project, namely the Canal Istanbul, was proposed to be built within this system parallel to the Bosphorus. Even tough environmental impacts of the project have been of concern, a few studies that address these scientific and public concerns under the light of scientific methods are available. In order to fill this gap in the literature, a three-dimensional hydrodynamic model with realistic forcing has been set up for long-term integration. The study includes simulating of two scenarios for the adjacent basins; (i) existing configuration of the TSS, and (ii) the proposed extension with the recent planned route of Canal Istanbul that was added to the validated model. The results reveals that the canal project would increase the exchange flow between the Black Sea and the Mediterranean Sea in both directions while causing slight changes in temperature & salinity along the TSS. Findings of this study can be used in further research that would analyze the impacts of the proposed Canal Istanbul on the water quality and ecosystem of the TSS. %0 journal article %@ 2296-7745 %A Li, D., Feng, J., Zhu, Y., Staneva, J., Qi, J., Behrens, A., Lee, D., Min, S.-K., Yin, B. %D 2022 %J Frontiers in Marine Science %P 844113 %R doi:10.3389/fmars.2022.844113 %T Dynamical Projections of the Mean and Extreme Wave Climate in the Bohai Sea, Yellow Sea and East China Sea %U https://doi.org/10.3389/fmars.2022.844113 %X Few studies have focused on the projected future changes in wave climate in the Chinese marginal seas. For the first time, we investigate the projected changes of the mean and extreme wave climate over the Bohai Sea, Yellow Sea, and East China Sea (BYE) during two future periods (2021–2050 and 2071–2100) under the RCP2.6 and RCP8.5 scenarios from the WAM wave model simulations with a resolution of 0.1°. This is currently the highest-resolution wave projection dataset available for the study domain. The wind forcings for WAM are from high-resolution (0.22°) regional climate model (RCM) CCLM-MPIESM simulations. The multivariate bias-adjustment method based on the N-dimensional probability density function transform is used to correct the raw simulated significant wave height (SWH), mean wave period (MWP), and mean wave direction (MWD). The annual and seasonal mean SWH are generally projected to decrease (-0.15 to -0.01 m) for 2021–2050 and 2071–2100 under the RCP2.6 and RCP8.5 scenarios, with statistical significance at a 0.1 level for most BYE in spring and for most of the Bohai Sea and Yellow Sea in annual and winter/autumn mean. There is a significant decrease in the spring MWP for two future periods under both the RCP2.6 and RCP8.5 scenarios. In contrast, the annual and summer/winter 99th percentile SWH are generally projected to increase for large parts of the study domain. Results imply that the projected changes in the mean and 99th percentile extreme waves are very likely related to projected changes in local mean and extreme surface wind speeds, respectively. %0 journal article %@ 2169-9275 %A Breivik, Ø., Carrasco, A., Haakenstad, H., Aarnes, O.J., Behrens, A., Bidlot, J.-R., Björkqvist, J.-V., Bohlinger, P., Furevik, B.R., Staneva, J., Reistad, M. %D 2022 %J Journal of Geophysical Research : Oceans %N 3 %P e2021JC018196 %R doi:10.1029/2021JC018196 %T The Impact of a Reduced High-Wind Charnock Parameter on Wave Growth With Application to the North Sea, the Norwegian Sea, and the Arctic Ocean %U https://doi.org/10.1029/2021JC018196 3 %X As atmospheric models move to higher resolution and resolve smaller scales, the maximum modeled wind speed also tends to increase. Wave models tuned to coarser wind fields tend to overestimate the wave growth under strong winds. A recently developed semiempirical parameterization of the Charnock parameter, which controls the roughness length over surface waves, substantially reduces the aerodynamic drag of waves in high winds (above a threshold of 30 m s−1). Here, we apply the formulation in a recent version of the wave model WAM (Cycle 4.7), which uses a modified version of the physics parameterizations by Ardhuin et al. (2010, https://doi.org/10.1175/2010jpo4324.1) as well as subgrid obstructions for better performance around complex topography. The new Charnock formulation is tested with wind forcing from NORA3, a recently completed nonhydrostatic atmospheric downscaling of the global reanalysis ERA5 for the North Sea, the Norwegian Sea and the Barents Sea. Such high-resolution atmospheric model integrations tend to have stronger (and more realistic) upper-percentile winds than what is typically found in coarser atmospheric models. A 2-year comparison (2011–2012) of a control run against the run with the modified Charnock parameter shows a dramatic reduction of the wave height bias in high-wind cases. The added computational cost of the new physics and the reduction of the Charnock parameter compared to the earlier WAM physics is modest (14%). A longer (1998–2020) hindcast integration with the new Charnock parameter is found to compare well against in situ and altimeter wave measurements both for intermediate and high sea states. %0 journal article %@ 1811-1602 %A Atwood, A., Bothe, O., Eggleston, S., Falster, G., Henley, B., Jones, M., Jonkers, L., Kaushal, N., Martrat, B., McGregor, H., Orsi, A., Phipps, S., Sayani, H. %D 2022 %J Past Global Changes Magazine %N 1 %P 52 %R doi:10.22498/pages.30.1.52 %T Phase 4 of the PAGES 2k Network: Hydroclimate of the Common Era %U https://doi.org/10.22498/pages.30.1.52 1 %X The PAGES 2k Network (pastglobalchanges.org/2k), founded in 2008, is one of the longest-running PAGES working groups. It has consistently achieved a high degree of community engagement and delivered significant datasets and publications. These have fundamentally improved our understanding of global climate changes through the Common Era. The 2k reconstructions of global temperature variability were featured in Figure 1 of the Summary for Policymakers of the IPCC’s Working Group I contribution to the Sixth Assessment Report (AR6; IPCC 2021). %0 journal article %@ 2296-7745 %A Samuelsen, A., Schrum, C., Yumruktepe, C., Daewel, U., Roberts, E. %D 2022 %J Frontiers in Marine Science %P 737164 %R doi:10.3389/fmars.2022.737164 %T Environmental Change at Deep-Sea Sponge Habitats Over the Last Half Century: A Model Hindcast Study for the Age of Anthropogenic Climate Change %U https://doi.org/10.3389/fmars.2022.737164 %X Deep-sea sponges inhabit multiple areas of the deep North Atlantic at depths below 250 m. Living in the deep ocean, where environmental properties below the permanent thermocline generally change slowly, they may not easily acclimatize to abrupt changes in the environment. Until now consistent monitoring timeseries of the environment at deep sea sponge habitats are missing. Therefore, long-term simulation with coupled bio-physical models can shed light on the changes in environmental conditions sponges are exposed to. To investigate the variability of North Atlantic sponge habitats for the past half century, the deep-sea conditions have been simulated with a 67-year model hindcast from 1948 to 2014. The hindcast was generated using the ocean general circulation model HYCOM, coupled to the biogeochemical model ECOSMO. The model was validated at known sponge habitats with available observations of hydrography and nutrients from the deep ocean to evaluate the biases, errors, and drift in the model. Knowing the biases and uncertainties we proceed to study the longer-term (monthly to multi-decadal) environmental variability at selected sponge habitats in the North Atlantic and Arctic Ocean. On these timescales, these deep sponge habitats generally exhibit small variability in the water-mass properties. Three of the sponge habitats, the Flemish Cap, East Greenland Shelf and North Norwegian Shelf, had fluctuations of temperature and salinity in 4–6 year periods that indicate the dominance of different water masses during these periods. The fourth sponge habitat, the Reykjanes Ridge, showed a gradual warming of about 0.4°C over the simulation period. The flux of organic matter to the sea floor had a large interannual variability, that, compared to the 67-year mean, was larger than the variability of primary production in the surface waters. Lateral circulation is therefore likely an important control mechanism for the influx of organic material to the sponge habitats. Simulated oxygen varies interannually by less than 1.5 ml/l and none of the sponge habitats studied had oxygen concentrations below hypoxic levels. The present study establishes a baseline for the recent past deep conditions that future changes in deep sea conditions from observations and climate models can be evaluated against. %0 journal article %@ 0043-1656 %A van Garderen, L., Mindlin, J. %D 2022 %J Weather %N 6 %P 212-218 %R doi:10.1002/wea.4185 %T A storyline attribution of the 2011/2012 drought in Southeastern South America %U https://doi.org/10.1002/wea.4185 6 %X The 2011/2012 summer drought in Southeastern South America (SESA) was a short but devastating event. What would this event have looked like under pre-industrial conditions, or in a +2 degC world? We find that climate change causes the region to be at a higher risk of drought. However, we found no large-scale changes in the half-month water budgets. We show that the climate change induced positive precipitation trend in the region outweighs the increased temperatures and potential evapotranspiration during the 2011/2012 drought. %0 journal article %@ 2662-138X %A Dastoor, A., Angot, H., Bieser, J., Christensen, J.H., Douglas, T.A., Heimbürger-Boavida, L.-E., Jiskra, M., Mason, R.P., McLagan, D.S., Obrist, D., Outridge, P.M., Petrova, M.V., Ryjkov, A., St. Pierre, K.A., Schartup, A.T., Soerensen, A.L., Toyota, K., Travnikov, O., Wilson, S.J., Zdanowicz, C. %D 2022 %J Nature Reviews. Earth & Environment %N 4 %P 270-286 %R doi:10.1038/s43017-022-00269-w %T Arctic mercury cycling %U https://doi.org/10.1038/s43017-022-00269-w 4 %X Anthropogenic mercury (Hg) emissions have driven marked increases in Arctic Hg levels, which are now being impacted by regional warming, with uncertain ecological consequences. This Review presents a comprehensive assessment of the present-day total Hg mass balance in the Arctic. Over 98% of atmospheric Hg is emitted outside the region and is transported to the Arctic via long-range air and ocean transport. Around two thirds of this Hg is deposited in terrestrial ecosystems, where it predominantly accumulates in soils via vegetation uptake. Rivers and coastal erosion transfer about 80 Mg year−1 of terrestrial Hg to the Arctic Ocean, in approximate balance with modelled net terrestrial Hg deposition in the region. The revised Arctic Ocean Hg mass balance suggests net atmospheric Hg deposition to the ocean and that Hg burial in inner-shelf sediments is underestimated (up to >100%), needing seasonal observations of sediment-ocean Hg exchange. Terrestrial Hg mobilization pathways from soils and the cryosphere (permafrost, ice, snow and glaciers) remain uncertain. Improved soil, snowpack and glacial Hg inventories, transfer mechanisms of riverine Hg releases under accelerated glacier and soil thaw, coupled atmosphere–terrestrial modelling and monitoring of Hg in sensitive ecosystems such as fjords can help to anticipate impacts on downstream Arctic ecosystems. %0 journal article %@ 0941-2948 %A Schulz-Stellenfleth, J., Emeis, S., Dorenkamper, M., Bange, J., Canadillas, B., Neumann, T., Schneemann, J., Weber, I., Zum Berge, K., Platis, A., Djath, B., Gottschall, J., Vollmer, L., Rausch, T., Barekzai, M., Hammel, J., Steinfeld, G., Lampert, A. %D 2022 %J Meteorologische Zeitschrift %N 4 %P 289-315 %R doi:10.1127/metz/2022/1109 %T Coastal impacts on offshore wind farms - a review focussing on the German Bight area %U https://doi.org/10.1127/metz/2022/1109 4 %X The atmospheric boundary layer experiences multiple changes in coastal regions, especially with wind directions from land towards the sea, where the wind speed usually increases due to the smaller roughness of the ocean surface. These effects are of particular relevance for offshore wind energy utilization; they are summarized under the term coastal effects. This paper provides an overview of coastal effects and their potential impact on the operating conditions of offshore wind farms with a focus on the German Bight. Common numerical and experimental tools to study coastal effects and developing internal boundary layers (IBL) are introduced, and a review on the current state of research is given. The German Bight is an interesting example to illustrate impacts of coastal effects on offshore wind energy, because of the large number of wind turbines with a coastal distance of 100 km or less. Phenomena related to the stability of the boundary layer, like low level jets, are discussed. Spatial variations of vertical heat fluxes in the coastal zone related to variable water depths or Wadden Sea areas are analysed. The study illustrates that due to the increasing size of offshore wind farms, horizontal wind speed gradients caused by coastal effects can lead to significant wind variations within a single farm. Research topics which still need further attention are discussed in the framework of the rapidly developing wind energy sector with increasing wind turbine hub heights and rotor diameters as well as growing wind farm sizes. One example is the interaction of coastal effects with offshore wind farm wakes. The necessity to consider a large spectrum of spatial and temporal scales to understand and describe coastal effects is highlighted. We summarize modelling and observation tools, which are suitable for the investigation and prediction of the boundary layer dynamics in coastal areas. Existing applications and results are described based on several examples with collocated observation and model results obtained in the X‑Wakes project. The study puts particular focus on the large potential provided by the combination of different measurements and modelling techniques and gives recommendations for future developments of integrated approaches including the formulation of priorities. %0 journal article %@ 0034-4257 %A Martin, A., Gommenginger, C., Jacob, B., Staneva, J. %D 2022 %J Remote Sensing of Environment %P 112758 %R doi:10.1016/j.rse.2021.112758 %T First multi-year assessment of Sentinel-1 radial velocity products using HF radar currents in a coastal environment %U https://doi.org/10.1016/j.rse.2021.112758 %X Finally, 1 km resolution maps of climatological S1A radial currents obtained over 2.5 years reveal strong coastal jets and fine scale details of the coastal circulation that closely match the known bathymetry and deep-water coastal channels in this region. The wealth of oceanographic information in corrected S1 RVL data is encouraging for Doppler oceanography from space and its application to observing small scale ocean dynamics, atmosphere and ocean vertical exchanges and marine ecosystem response to environmental change. %0 journal article %@ 2296-7745 %A Miesner, A., Brune, S., Pieper, P., Koul, V., Baehr, J., Schrum, C. %D 2022 %J Frontiers in Marine Science %P 777427 %R doi:10.3389/fmars.2021.777427 %T Exploring the Potential of Forecasting Fish Distributions in the North East Atlantic With a Dynamic Earth System Model, Exemplified by the Suitable Spawning Habitat of Blue Whiting %U https://doi.org/10.3389/fmars.2021.777427 %X Local oceanographic variability strongly influences the spawning distribution of blue whiting (Micromesistius poutassou). Here, we explore the potential of using a dynamic Earth System Model (ESM) to forecast the suitable spawning habitat of blue whiting to assist management. Retrospective forecasts of temperature and salinity with the Max Planck Institute ESM (MPI-ESM) show significant skill within blue whiting’s spawning region and spawning depth (250–600 m) during the peak months of spawning. While persistence forecasts perform well at shorter lead times (≤2 years), retrospective forecasts with MPI-ESM are clearly more skilful than persistence in predicting salinity at longer lead times. Our results indicate that retrospective forecasts of the suitable spawning habitat of blue whiting based on predicted salinity outperform those based on calibrated species distribution models. In particular, we find high predictive skill for the suitable spawning habitat based on salinity predictions around one year ahead in the area of Rockall-Hatton Plateau. Our approach shows that retrospective forecasts with MPI-ESM show a better ability to differentiate between the presence and absence of suitable habitat over Rockall Plateau compared to persistence. Our study highlights that physical-biological forecasts based on ESMs could be crucial for developing distributional forecasts of marine organisms in the North East Atlantic. %0 journal article %@ 2296-7745 %A Koul, V., Brune, S., Baehr, J., Schrum, C. %D 2022 %J Frontiers in Marine Science %P 778335 %R doi:10.3389/fmars.2021.778335  %T Impact of Decadal Trends in the Surface Climate of the North Atlantic Subpolar Gyre on the Marine Environment of the Barents Sea %U https://doi.org/10.3389/fmars.2021.778335  %X The Barents Sea is a key region in the Earth System and is home to highly productive marine resources. An integrated approach for strategic sustainable management of marine resources in such shelf-sea marine ecosystems requires, among many other aspects, a robust understanding of the impact of climate on local oceanic conditions. Here, using a combined observational and modelling approach, we show that decadal climatic trends associated with the North Atlantic Subpolar Gyre (SPG), within the period 1960–2019, have an impact on oceanic conditions in the Barents Sea. We relate hydrographic conditions in the Barents Sea to the decadal variability of the SPG through its impact on the Atlantic Inflow via the Faroe-Shetland Channel and the Barents Sea Opening. When the SPG warms, an increase in the throughput of subtropical waters across the Greenland-Scotland Ridge is followed by an increase in the volume of Atlantic Water entering the Barents Sea. These changes are reflected in pronounced decadal trends in the sea-ice concentration and primary production in the Barents Sea, which follow the SPG after an advective delay of 4–5 years. This impact of the SPG on sea-ice and primary production provides a dynamical explanation of the recently reported 7-year lagged statistical relationship between SPG and cod (Gadus morhua) biomass in the Barents Sea. Overall, these results highlight a potential for decadal ecosystem predictions in the Barents Sea. %0 journal article %@ 2212-4209 %A de Guttry, C., Ratter, B. %D 2022 %J International Journal of Disaster Risk Reduction %P 102719 %R doi:10.1016/j.ijdrr.2021.102719 %T Expiry date of a disaster: Memory anchoring and the storm surge 1962 in Hamburg, Germany %U https://doi.org/10.1016/j.ijdrr.2021.102719 %X Disasters are events often perceived to be confined in time and in space. In this paper we challenge this assumption by focusing on the memory of disaster as key aspect through which it is possible to go beyond the “there and then” of a disaster. By applying the concept of memory anchoring, we illustrate the importance of memory for its repercussions on the present “here and now” as well as on the future way of dealing with disasters. We apply the framework of memory anchors to the case study of the Storm Surge 1962 and the following flood disaster, which took place in Hamburg, Germany and marked a turning point in Hamburg's disaster history. This disaster is locally constructed as memory anchor by those who directly experienced it, and those who have to deal with natural hazards in the city's administration. We scrutinize how different actors enact the memory anchoring process and with what aims. The process of memory anchoring is reflected in locational and societal representations and therefore supports the imaginaries of space and time of the disaster. However, which role can memory anchors play in future disaster awareness and management? Which role do they play in policy decisions on flood management? And how can memory anchors impact future generations in their dealing with disasters? The question remains on how (and if) it is possible to prevent disappearance of memory anchors without the need of a further disaster. %0 journal article %@ 2296-7745 %A Christiansen, N., Daewel, U., Djath, B., Schrum, C. %D 2022 %J Frontiers in Marine Science %P 818501 %R doi:10.3389/fmars.2022.818501 %T Emergence of Large-Scale Hydrodynamic Structures Due to Atmospheric Offshore Wind Farm Wakes %U https://doi.org/10.3389/fmars.2022.818501 %X The potential impact of offshore wind farms through decreasing sea surface wind speed on the shear forcing and its consequences for the ocean dynamics are investigated. Based on the unstructured-grid model SCHISM, we present a new cross-scale hydrodynamic model setup for the southern North Sea, which enables high-resolution analysis of offshore wind farms in the marine environment. We introduce an observational-based empirical approach to parameterize the atmospheric wakes in a hydrodynamic model and simulate the seasonal cycle of the summer stratification in consideration of the recent state of wind farm development in the southern North Sea. The simulations show the emergence of large-scale attenuation in the wind forcing and associated alterations in the local hydro- and thermodynamics. The wake effects lead to unanticipated spatial variability in the mean horizontal currents and to the formation of large-scale dipoles in the sea surface elevation. Induced changes in the vertical and lateral flow are sufficiently strong to influence the residual currents and entail alterations of the temperature and salinity distribution in areas of wind farm operation. Ultimately, the dipole-related processes affect the stratification development in the southern North Sea and indicate potential impact on marine ecosystem processes. In the German Bight, in particular, we observe large-scale structural change in stratification strength, which eventually enhances the stratification during the decline of the summer stratification toward autumn. %0 journal article %@ 2169-8961 %A Meng, Q., Zhang, W., Zhou, F., Liao, Y., Yu, P., Tang, Y., Ma, X., Di, T., Ding, R., Ni, X., Zeng, D., Schrum, C. %D 2022 %J Journal of Geophysical Research : Biogeosciences %N 2 %P e2021JG006705 %R doi:10.1029/2021JG006705 %T Water Oxygen Consumption Rather Than Sediment Oxygen Consumption Drives the Variation of Hypoxia on the East China Sea Shelf %U https://doi.org/10.1029/2021JG006705 2 %X Sediment oxygen consumption (SOC) is important in modulating the oxygen budget in the East China Sea where seasonal hypoxia occurs. Porewater advection, molecular diffusion and bioturbation supply oxygen for sedimentary organic matter degradation. A pelagic‒benthic coupled model was applied to quantify the SOC. A comparison with observations showed good model performance in reproducing the hydrographic and ecological environments, particularly for the interannual variation in the hypoxic zone. Simulation results show that porewater-advection-induced flux is the predominant component of the SOC in sandy areas on the Changjiang bank and outer shelves, while the bioturbation‒induced flux is predominant at mud depocenters. By comparing SOC to the water oxygen consumption (WOC) below the pycnocline, the contribution of SOC is generally below ∼40% in the hypoxic zone. The spatial distribution of SOC in summer is relatively steady from year to year, while the high WOC patches explain more about the interannual variation in the hypoxic zone. WOC rather than SOC drives the variation of hypoxia. Particularly on the Changjiang bank, milder hydrodynamics are favorable for both the higher WOC and bioturbation-induced benthic oxygen flux but substantially suppress the porewater advective flux, which results in the net lower contribution of SOC to hypoxia. This finding may shed light on other pelagic‒benthic coupling processes in coastal shelf seas where hypoxia occurs on permeable sediments. %0 journal article %@ 0930-7575 %A Büntgen, U., Smith, S.H., Wagner, S., Krusic, P., Esper, J., Piermattei, A., Crivellaro, A., Reinig, F., Tegel, W., Kirdyanov, A., Trnka, M., Oppenheimer, C. %D 2022 %J Climate Dynamics %P 531-546 %R doi:10.1007/s00382-022-06141-3 %T Global tree-ring response and inferred climate variation following the mid-thirteenth century Samalas eruption %U https://doi.org/10.1007/s00382-022-06141-3 %X The largest explosive volcanic eruption of the Common Era in terms of estimated sulphur yield to the stratosphere was identified in glaciochemical records 40 years ago, and dates to the mid-thirteenth century. Despite eventual attribution to the Samalas (Rinjani) volcano in Indonesia, the eruption date remains uncertain, and the climate response only partially understood. Seeking a more global perspective on summer surface temperature and hydroclimate change following the eruption, we present an analysis of 249 tree-ring chronologies spanning the thirteenth century and representing all continents except Antarctica. Of the 170 predominantly temperature sensitive high-frequency chronologies, the earliest hints of boreal summer cooling are the growth depressions found at sites in the western US and Canada in 1257 CE. If this response is a result of Samalas, it would be consistent with an eruption window of circa May–July 1257 CE. More widespread summer cooling across the mid-latitudes of North America and Eurasia is pronounced in 1258, while records from Scandinavia and Siberia reveal peak cooling in 1259. In contrast to the marked post-Samalas temperature response at high-elevation sites in the Northern Hemisphere, no strong hydroclimatic anomalies emerge from the 79 precipitation-sensitive chronologies. Although our findings remain spatially biased towards the western US and central Europe, and growth-climate response patterns are not always dominated by a single meteorological factor, this study offers a global proxy framework for the evaluation of paleoclimate model simulations. %0 journal article %@ 2624-9553 %A Bouwer, L., Cheong, S., Jacot Des Combes, H., Frölicher, T., McInnes, K., Ratter, B., Rivera-Arriaga, E. %D 2022 %J Frontiers in Climate %P 785641 %R doi:10.3389/fclim.2021.785641 %T Risk Management and Adaptation for Extremes and Abrupt Changes in Climate and Oceans: Current Knowledge Gaps %U https://doi.org/10.3389/fclim.2021.785641 %X Perspectives for risk management and adaptation have received ample attention in the recent IPCC Special Report on Changes in the Oceans and Cryosphere (SROCC). However, several knowledge gaps on the impacts of abrupt changes, cascading effects and compound extreme climatic events have been identified, and need further research. We focus on specific climate change risks identified in the SROCC report, namely: changes in tropical and extratropical cyclones; marine heatwaves; extreme ENSO events; and abrupt changes in the Atlantic Meridional Overturning Circulation. Several of the socioeconomic impacts from these events are not yet well-understood, and the literature is also sparse on specific recommendations for integrated risk management and adaptation options to reduce such risks. Also, past research has mostly focussed on concepts that have seen little application to real-world cases. We discuss relevant research needs and priorities for improved social-ecological impact assessment related to these major physical changes in the climate and oceans. For example, harmonised approaches are needed to better understand impacts from compound events, and cascading impacts across systems. Such information is essential to inform options for adaptation, governance and decision-making. Finally, we highlight research needs for developing transformative adaptation options and their governance. %0 journal article %@ 0025-3227 %A Chen, H., Zhang, W., Xie, X., Gao, Y., Liu, S., Ren, J., Wang, D., Su, M. %D 2022 %J Marine Geology %P 106714 %R doi:10.1016/j.margeo.2021.106714 %T Linking oceanographic processes to contourite features: Numerical modelling of currents influencing a contourite depositional system on the northern South China Sea margin %U https://doi.org/10.1016/j.margeo.2021.106714 %X The results of this study show a clear link between bottom currents' behaviours (e.g., mean flow condition and variability) and contouritic depositional patterns, which suggest that continental slopes can be effectively shaped by large-scale ocean circulations through the topography-current interaction. The weakest hydrodynamic condition and highest sediment accumulation rate, occurring in the ~800 m thick transition domain between two water masses in the study area, facilitate the development of plastered drifts at the seaward side of contourite terraces. The outcomes of our study may have broad implications for understanding the relationship between processes and products in continental margins. %0 journal article %@ 1561-8633 %A Liu, X., Meinke, I., Weisse, R. %D 2022 %J Natural Hazards and Earth System Sciences %N 1 %P 97-116 %R doi:10.5194/nhess-22-97-2022 %T Still normal? Near-real-time evaluation of storm surge events in the context of climate change %U https://doi.org/10.5194/nhess-22-97-2022 1 %X Storm surges represent a major threat to many low-lying coastal areas in the world. In the aftermath of an extreme event, the extent to which the event was unusual and the potential contribution of climate change in shaping the event are often debated. Commonly analyzes that allow for such assessments are not available right away but are only provided with often considerable time delay. To address this gap, a new tool was developed and applied to storm surges along the German North Sea and Baltic Sea coasts. The tool integrates real-time measurements with long-term statistics to put ongoing extremes or the course of a storm surge season into a climatological perspective in near real time. The approach and the concept of the tool are described and discussed. To illustrate the capabilities, several exemplary cases from the storm surge seasons 2018/2019 and 2019/2020 are discussed. It is concluded that the tool provides support in the near-real-time assessment and evaluation of storm surge extremes. It is further argued that the concept is transferable to other regions and/or coastal hazards. %0 journal article %@ 2190-4979 %A Reckermann, M., Omstedt, A., Soomere, T., Aigars, J., Akhtar, N., Bełdowska, M., Bełdowski, J., Cronin, T., Czub, M., Eero, M., Hyytiäinen, K.P., Jalkanen, J.-P., Kiessling, A., Kjellström, E., Kuliński, K., Larsén, X.G., McCrackin, M., Meier, H.E.M., Oberbeckmann, S., Parnell, K., Pons-Seres De Brauwer, C., Poska, A., Saarinen, J., Szymczycha, B., Undeman, E., Wörman, A., Zorita, E. %D 2022 %J Earth System Dynamics %N 1 %P 1-80 %R doi:10.5194/esd-13-1-2022 %T Human impacts and their interactions in the Baltic Sea region %U https://doi.org/10.5194/esd-13-1-2022 1 %X Coastal environments, in particular heavily populated semi-enclosed marginal seas and coasts like the Baltic Sea region, are strongly affected by human activities. A multitude of human impacts, including climate change, affect the different compartments of the environment, and these effects interact with each other. As part of the Baltic Earth Assessment Reports (BEAR), we present an inventory and discussion of different human-induced factors and processes affecting the environment of the Baltic Sea region, and their interrelations. Some are naturally occurring and modified by human activities (i.e. climate change, coastal processes, hypoxia, acidification, submarine groundwater discharges, marine ecosystems, non-indigenous species, land use and land cover), some are completely human-induced (i.e. agriculture, aquaculture, fisheries, river regulations, offshore wind farms, shipping, chemical contamination, dumped warfare agents, marine litter and microplastics, tourism, and coastal management), and they are all interrelated to different degrees. We present a general description and analysis of the state of knowledge on these interrelations. Our main insight is that climate change has an overarching, integrating impact on all of the other factors and can be interpreted as a background effect, which has different implications for the other factors. Impacts on the environment and the human sphere can be roughly allocated to anthropogenic drivers such as food production, energy production, transport, industry and economy. The findings from this inventory of available information and analysis of the different factors and their interactions in the Baltic Sea region can largely be transferred to other comparable marginal and coastal seas in the world. %0 journal article %@ 2523-3521 %A Tian, D., Zhou, F., Zhang, W., Zhang, H., Ma, X., Guo, X. %D 2022 %J Journal of Oceanology and Limnology %N 2 %P 515-529 %R doi:10.1007/s00343-021-0440-3 %T Effects of dissolved oxygen and nutrients from the Kuroshio on hypoxia off the Changjiang River estuary %U https://doi.org/10.1007/s00343-021-0440-3 2 %X The intrusion of the Kuroshio into the East China Sea (ECS) affects the development of hypoxia off the Changjiang (Yangtze) River estuary; however, quantitative analysis of its impacts is lacking. In this study, the Regional Ocean Modeling Systems (ROMS) model coupled with the Carbon, Silicate and Nitrogen Ecosystem (CoSiNE) model was used to investigate the relative importance of dissolved oxygen (DO) and different nutrients (silicate, nitrate, and phosphate) in the Kuroshio on hypoxia in the ECS. Results show that changes in DO concentrations in the Kuroshio modify the distribution and intensity of hypoxia through direct onshore transport by hydrodynamic processes. An increase in Kuroshio DO concentration by 25% or 50% would result in a decrease of the maximum hypoxia extent (MHE) in the ECS by 76% or 86%, respectively, while a 25% decrease in Kuroshio DO would increase the MHE by up to 219%. The contribution of DO in the Taiwan Strait is almost negligible. In contrast to Kuroshio DO, nutrients affect hypoxia in the ECS through onshore transport by hydrodynamic and biochemical processes. Changes in phosphate and nitrate concentrations by 25% in the Kuroshio would change the MHE by up to 30% and 18%, respectively, accompanied by apparent changes in surface chlorophyll-a concentrations. The effect of silicate on hypoxia is negligible because a 25% change in silicate concentrations in the Kuroshio would result in less than 1% change in the MHE. Our results reveal a hierarchical rank of importance for environmental variables in the Kuroshio (i.e., DO > phosphate > nitrate > silicate) in modifying the development of hypoxia in the ECS. %0 journal article %@ 0930-7575 %A Liu, F., Mikolajewicz, U., Six, K. %D 2022 %J Climate Dynamics %P 2065-2077 %R doi:10.1007/s00382-021-05714-y %T Drivers of the decadal variability of the North Ionian Gyre upper layer circulation during 1910–2010: a regional modelling study %U https://doi.org/10.1007/s00382-021-05714-y %X A long simulation over the period 1901–2010 with an eddy-permitting ocean circulation model is used to study the variability of the upper layer circulation in the North Ionian Gyre (NIG) in the Eastern Mediterranean Sea (EMed). The model is driven by the atmospheric forcing from the twentieth century reanalysis data set ERA-20C, ensuring a consistent performance of the model over the entire simulation period. The main modes of variability known in the EMed, in particular the decadal reversals of the NIG upper layer circulation observed since the late 1980s are well reproduced. We find that the simulated NIG upper layer circulation prior to the observational period is characterized by long-lasting cyclonic phases with weak variability during years 1910–1940 and 1960–1985, while in the in-between period (1940–1960) quasi-decadal NIG circulation reversals occur with similar characteristics to those observed in the recent decades. Our simulation indicates that the NIG upper layer circulation is rather prone to the cyclonic mode with occasional kicks to the anticyclonic mode. The coherent variability of the NIG upper layer circulation mode and of the Adriatic Deep Water (AdDW) outflow implies that atmospheric forcing triggering strong AdDW formation is required to kick the NIG into an anticyclonic circulation 1–2 years later. A sensitivity experiment mimicking a cold winter event over the Adriatic Sea supports this hypothesis. Our simulation shows that it is the multi-decadal variability of the salinity in the Adriatic Sea that leads to periods where low salinity prevents strong AdDW formation events. This explains the absence of quasi-decadal NIG reversals during 1910–1940 and 1960–1985. %0 journal article %@ 2041-1723 %A Payne, M., Danabasoglu, G., Keenlyside. N., Matei, D., Miesner, A., Yang, S., Yeager, S. %D 2022 %J Nature Communications %P 2660 %R doi:10.1038/s41467-022-30280-0 %T Skilful decadal-scale prediction of fish habitat and distribution shifts %U https://doi.org/10.1038/s41467-022-30280-0 %X Many fish and marine organisms are responding to our planet’s changing climate by shifting their distribution. Such shifts can drive international conflicts and are highly problematic for the communities and businesses that depend on these living marine resources. Advances in climate prediction mean that in some regions the drivers of these shifts can be forecast up to a decade ahead, although forecasts of distribution shifts on this critical time-scale, while highly sought after by stakeholders, have yet to materialise. Here, we demonstrate the application of decadal-scale climate predictions to the habitat and distribution of marine fish species. We show statistically significant forecast skill of individual years that outperform baseline forecasts 3–10 years ahead; forecasts of multi-year averages perform even better, yielding correlation coefficients in excess of 0.90 in some cases. We also demonstrate that the habitat shifts underlying conflicts over Atlantic mackerel fishing rights could have been foreseen. Our results show that climate predictions can provide information of direct relevance to stakeholders on the decadal-scale. This tool will be critical in foreseeing, adapting to and coping with the challenges of a changing future climate, particularly in the most ocean-dependent nations and communities. %0 journal article %@ 0044-7447 %A Heath, M., Benkort, D., Brierley, A., Daewel, U., Laverick, J., Proud, R., Speirs, D. %D 2022 %J Ambio %N 2 %P 456-470 %R doi:10.1007/s13280-021-01616-9 %T Ecosystem approach to harvesting in the Arctic: Walking the tightrope between exploitation and conservation in the Barents Sea %U https://doi.org/10.1007/s13280-021-01616-9 2 %X Projecting the consequences of warming and sea-ice loss for Arctic marine food web and fisheries is challenging due to the intricate relationships between biology and ice. We used StrathE2EPolar, an end-to-end (microbes-to-megafauna) food web model incorporating ice-dependencies to simulate climate-fisheries interactions in the Barents Sea. The model was driven by output from the NEMO-MEDUSA earth system model, assuming RCP 8.5 atmospheric forcing. The Barents Sea was projected to be > 95% ice-free all year-round by the 2040s compared to > 50% in the 2010s, and approximately 2 °C warmer. Fisheries management reference points (FMSY and BMSY) for demersal fish (cod, haddock) were projected to increase by around 6%, indicating higher productivity. However, planktivorous fish (capelin, herring) reference points were projected to decrease by 15%, and upper trophic levels (birds, mammals) were strongly sensitive to planktivorous fish harvesting. The results indicate difficult trade-offs ahead, between harvesting and conservation of ecosystem structure and function. %0 journal article %@ 2296-7745 %A Thewes, D., Stanev, E., Zielinski, O. %D 2022 %J Frontiers in Marine Science %P 818383 %R doi:10.3389/fmars.2022.818383 %T Steps Toward Modelling the Past and Future North Sea Ecosystem With a Focus on Light Climate %U https://doi.org/10.3389/fmars.2022.818383 %X With ongoing manmade climate change, it is important to understand its impact on regional ecosystems. Furthermore, it is known that the North Sea light climate is subject to ongoing change. The combined effects of climate change and coastal darkening are investigated in this work. We used a three-dimensional ecosystem model, forced with data from a climate model, to project three plausible biogeochemical states for the years 2050–2054, following three representative concentration and shared socioeconomic pathways (RCP2.6-SSP1, RCP4.5-SSP2 and RCP8.5-SSP5). We also performed a historic experiment for the years 1950–1954 and 2000–2004 for comparison. Our results suggest significant reductions of phytoplankton biomass as a consequence of sinking nutrient levels for all future scenarios. Additionally, a modelling study was carried out, in which we raised background SPM levels by 40% to reflect potential changes in the future. This revealed that for RCP2.6-SSP1, the ecosystem is more sensitive to changes in the light climate than for the other scenarios, due to higher nutrient availability. %0 journal article %@ 0377-0265 %A Lin, L., von Storch, H., Guo, D., Tang, S., Zheng, P., Chen, X. %D 2022 %J Dynamics of Atmospheres and Oceans %P 101301 %R doi:10.1016/j.dynatmoce.2022.101301 %T The effect of tides on internal variability in the Bohai and Yellow Sea %U https://doi.org/10.1016/j.dynatmoce.2022.101301 %X The first result was that in all three ensembles, noise emerged but with different intensities. In the ensemble with tidal forcing, unprovoked variability emerged primarily at smaller scales. When the tides were weakened or turned off, the S/N ratios were reduced, more so in the Yellow Sea than in the Bohai. The increase in the S/N ratio was largest for large scales and for depth-averaged velocities. The reduction in tidal forcing resulted in an approximately 30% increase in S/N ratios in the Bohai at large scales. Thus, the absence of tidal forcing favored the emergence of increased unprovoked variability at large and medium scales but not at small scales. A hypothesis for explaining this scale-selective effect of tides, based on the stochastic climate model, was suggested. %0 journal article %@ 1561-8633 %A Chen, W., Staneva, J., Grayek, S., Schulz-Stellenfleth, J., Greinert, J. %D 2022 %J Natural Hazards and Earth System Sciences %N 5 %P 1683-1698 %R doi:10.5194/nhess-22-1683-2022 %T The role of heat wave events in the occurrence and persistence of thermal stratification in the southern North Sea %U https://doi.org/10.5194/nhess-22-1683-2022 5 %X Temperature extremes not only directly affect the marine environment and ecosystems but also indirectly influence hydrodynamics and marine life. In this study, the role of heat wave events in the occurrence and persistence of thermal stratification was analysed by simulating the water temperature of the North Sea from 2011 to 2018 using a fully coupled hydrodynamic and wave model within the framework of the Geesthacht Coupled cOAstal model SysTem (GCOAST). The model results were assessed against reprocessed satellite data and in situ observations from field campaigns and fixed Marine Environmental Monitoring Network (MARNET) stations. To quantify the degree of stratification, the potential energy anomaly throughout the water column was calculated. The air temperatures and potential energy anomalies in the North Sea (excluding the Norwegian Trench and the area south of 54∘ N) were linearly correlated. Different from the northern North Sea, where the water column is stratified in the warm season each year, the southern North Sea is seasonally stratified in years when a heat wave occurs. The influences of heat waves on the occurrence of summer stratification in the southern North Sea are mainly in the form of two aspects, i.e. a rapid rise in sea surface temperature at the early stage of the heat wave period and a higher water temperature during summer than the multiyear mean. Another factor that enhances the thermal stratification in summer is the memory of the water column to cold spells earlier in the year. Differences between the seasonally stratified northern North Sea and the heat wave-induced stratified southern North Sea were ultimately attributed to changes in water depth. %0 journal article %@ 1991-959X %A Yumruktepe, V., Samuelsen, A., Daewel, U. %D 2022 %J Geoscientific Model Development %N 9 %P 3901-3921 %R doi:10.5194/gmd-15-3901-2022 %T ECOSMO II(CHL): a marine biogeochemical model for the North Atlantic and the Arctic %U https://doi.org/10.5194/gmd-15-3901-2022 9 %X ECOSMO II is a fully coupled bio-physical model of 3D hydrodynamics with an intermediate-complexity NPZD (nutrient, phytoplankton, zooplankton, detritus) type biology including sediment-water column exchange processes originally formulated for the North Sea and Baltic Sea. Here we present an updated version of the model incorporating chlorophyll a as a prognostic state variable: ECOSMO II(CHL). The version presented here is online coupled to the HYCOM ocean model. The model is intended to be used for regional configurations for the North Atlantic and the Arctic incorporating coarse to high spatial resolutions for hind-casting and operational purposes. We provide the full descriptions of the changes in ECOSMO II(CHL) from ECOSMO II and provide the evaluation for the inorganic nutrients and chlorophyll a variables, present the modelled biogeochemistry of the Nordic Seas and the Arctic, and experiment on various parameterization sets as use cases targeting chlorophyll a dynamics. We document the performance of each parameter set objectively analysing the experiments against in situ, satellite and climatology data. The model evaluations for each experiment demonstrated that the simulations are consistent with the large-scale climatological nutrient setting and are capable of representing regional and seasonal changes. Explicitly resolving chlorophyll a allows for more dynamic seasonal and vertical variations in phytoplankton biomass to chlorophyll a ratio and improves model chlorophyll a performance near the surface. Through experimenting with the model performance, we document the general biogeochemisty of the Nordic Seas and the Arctic. The Norwegian and Barents seas primary production show distinct seasonal patterns with a pronounced spring bloom dominated by diatoms and low biomass during winter months. The Norwegian Sea annual primary production is around double that of the Barents Sea while also having an earlier spring bloom. %0 journal article %@ 2296-7745 %A Christiansen, N., Daewel, U., Schrum, C. %D 2022 %J Frontiers in Marine Science %P 1006647 %R doi:10.3389/fmars.2022.1006647 %T Tidal mitigation of offshore wind wake effects in coastal seas %U https://doi.org/10.3389/fmars.2022.1006647 %X With increasing offshore wind development, more and more marine environments are confronted with the effects of atmospheric wind farm wakes on hydrodynamic processes. Recent studies have highlighted the impact of the wind wakes on ocean circulation and stratification. In this context, however, previous studies indicated that wake effects appear to be attenuated in areas strongly determined by tidal energy. In this study, we therefore determine the role of tides in wake-induced hydrodynamic perturbations and assess the importance of the local hydrodynamic conditions on the magnitude of the emerging wake effects on hydrodynamics. By using an existing high-resolution model setup for the southern North Sea, we performed different scenario simulations to identify the tidal impact. The results show the impact of the alignment between wind and ocean currents in relation to the hydrodynamic changes that occur. In this regard, tidal currents can deflect emerging changes in horizontal surface currents and even mitigate the mean changes in horizontal flow due to periodic perturbations of wake signals. We identified that, particularly in shallower waters, tidal stirring influences how wind wake effects translate to changes in vertical transport and density stratification. In this context, tidal mixing fronts can serve as a natural indicator of the expected magnitude of stratification changes due to atmospheric wakes. Ultimately, tide-related hydrodynamic features, like periodic currents and mixing fronts, influence the development of wake effects in the coastal ocean. Our results provide important insights into the role of hydrodynamic conditions in the impact of atmospheric wake effects, which are essential for assessing the consequences of offshore wind farms in different marine environments. %0 journal article %@ 1561-8633 %A Krieger, D., Brune, S., Pieper, P., Weisse, R., Baehr, J. %D 2022 %J Natural Hazards and Earth System Sciences %N 12 %P 3993-4009 %R doi:10.5194/nhess-22-3993-2022 %T Skillful decadal prediction of German Bight storm activity %U https://doi.org/10.5194/nhess-22-3993-2022 12 %X We evaluate the prediction skill of the Max Planck Institute Earth System Model (MPI-ESM) decadal hindcast system for German Bight storm activity (GBSA) on a multiannual to decadal scale. We define GBSA every year via the most extreme 3-hourly geostrophic wind speeds, which are derived from mean sea-level pressure (MSLP) data. Our 64-member ensemble of annually initialized hindcast simulations spans the time period 1960–2018. For this period, we compare deterministically and probabilistically predicted winter MSLP anomalies and annual GBSA with a lead time of up to 10 years against observations. The model produces poor deterministic predictions of GBSA and winter MSLP anomalies for individual years but fair predictions for longer averaging periods. A similar but smaller skill difference between short and long averaging periods also emerges for probabilistic predictions of high storm activity. At long averaging periods (longer than 5 years), the model is more skillful than persistence- and climatology-based predictions. For short aggregation periods (4 years and less), probabilistic predictions are more skillful than persistence but insignificantly differ from climatological predictions. We therefore conclude that, for the German Bight, probabilistic decadal predictions (based on a large ensemble) of high storm activity are skillful for averaging periods longer than 5 years. Notably, a differentiation between low, moderate, and high storm activity is necessary to expose this skill. %0 journal article %@ 2624-9553 %A Mayer, B., Mathis, M., Mikolajewicz, U., Pohlmann, T. %D 2022 %J Frontiers in Climate %P 992119 %R doi:10.3389/fclim.2022.992119 %T RCP8.5-projected changes in German Bight storm surge characteristics from regionalized ensemble simulations for the end of the twenty-first century %U https://doi.org/10.3389/fclim.2022.992119 %X This study investigates climate-induced changes in height, frequency and duration of storm surges in the German Bight. The regionally coupled climate model system MPIOM-REMO with a focus on the North Sea has been utilized to dynamically downscale 30 members of the global climate model system MPI-ESM1.1-LR for the historical period 1950–2005 and a continuation until 2099 with the RCP8.5 scenario. Results of all members have been collected into the historical (1970–1999) and the rcp85 (2070–2099) data pools amounting to 900 years of the corresponding climate state. The global mean sea level rise was not considered. Nevertheless, the mean ensemble German Bight SSH trend amounts to about 13 ± 1 cm/century (PI control: 3 cm/century) due to adaptation of the ocean circulation to the changing climatic conditions. Storm surges were defined as SSH above mean high tidal water plus 1.5, 2.5, 3.5 m for “regular”, heavy, extreme storm surges, and then clustered to events. Our simulated storm surge events show a clear location-dependent increase in frequency (6–11%), median duration (4–24%), and average duration (9–20%) in the German Bight. Only along the central German Bight coast (Cuxhaven), longer lasting events gain more relevance. Heavy storm surge events show also a strong increase in frequency (7–34%) and average duration (10–22%). Maximum sea levels during storm events increase strongest and most significant along the northern German Bight and Danish coasts with more than 30 cm/century for the 60-year return period at Hörnum and 10–15 cm/century for shorter return periods. Levels of return periods shorter than a few years significantly increase everywhere along the southern German Bight coasts (around 5 cm/century for the 2-year return period). Highest SSH maxima do not change, and consequently, extreme storm surge events show hardly any response to climate change. Furthermore, our results indicate a shift of seasonality from the last to the first quarter of a year. As the main driver for the encountered alteration of German Bight storm surge characteristics, we identified a change in wind conditions with a pronounced increase of frequency of strong westerly winds. %0 journal article %@ 1942-2466 %A Jungclaus, J.H., Lorenz, S.J., Schmidt, H., Brovkin, V., Brüggemann, N., Chegini, F., Crüger, T., De-Vrese, P., Gayler, V., Giorgetta, M.A., Gutjahr, O., Haak, H., Hagemann, S., Hanke, M., Ilyina, T., Korn, P., Kröger, J., Linardakis, L., Mehlmann, C., Mikolajewicz, U., Müller, W.A., Nabel, J.E.M.S., Notz, D., Pohlmann, H., Putrasahan, D.A., Raddatz, T., Ramme, L., Redler, R., Reick, C.H., Riddick, T., Sam, T., Schneck, R., Schnur, R., Schupfner, M., von Storch, J.-S., Wachsmann, F., Wieners, K.-H., Ziemen, F., Stevens, B., Marotzke, J., Claussen, M. %D 2022 %J Journal of Advances in Modeling Earth Systems : JAMES %N 4 %P e2021MS002813 %R doi:10.1029/2021MS002813 %T The ICON Earth System Model version 1.0 %U https://doi.org/10.1029/2021MS002813 4 %X This work documents the ICON-Earth System Model (ICON-ESM V1.0), the first coupled model based on the ICON (ICOsahedral Non-hydrostatic) framework with its unstructured, icosahedral grid concept. The ICON-A atmosphere uses a nonhydrostatic dynamical core and the ocean model ICON-O builds on the same ICON infrastructure, but applies the Boussinesq and hydrostatic approximation and includes a sea-ice model. The ICON-Land module provides a new framework for the modeling of land processes and the terrestrial carbon cycle. The oceanic carbon cycle and biogeochemistry are represented by the Hamburg Ocean Carbon Cycle module. We describe the tuning and spin-up of a base-line version at a resolution typical for models participating in the Coupled Model Intercomparison Project (CMIP). The performance of ICON-ESM is assessed by means of a set of standard CMIP6 simulations. Achievements are well-balanced top-of-atmosphere radiation, stable key climate quantities in the control simulation, and a good representation of the historical surface temperature evolution. The model has overall biases, which are comparable to those of other CMIP models, but ICON-ESM performs less well than its predecessor, the Max Planck Institute Earth System Model. Problematic biases are diagnosed in ICON-ESM in the vertical cloud distribution and the mean zonal wind field. In the ocean, sub-surface temperature and salinity biases are of concern as is a too strong seasonal cycle of the sea-ice cover in both hemispheres. ICON-ESM V1.0 serves as a basis for further developments that will take advantage of ICON-specific properties such as spatially varying resolution, and configurations at very high resolution. %0 journal article %@ 2662-4435 %A Erikson, L., Morim, J., Hemer, M., Young, I., Wang, X.L., Mentaschi, L., Mori, N., Semedo, A., Stopa, J., Grigorieva, V., Gulev, S., Aarnes, O., Bidlot, J.-R., Breivik, Ø., Bricheno, L., Shimura, T., Menendez, M., Markina, M., Sharmar, V., Trenham, C., Wolf, J., Appendini, C., Caires, S., Groll, N., Webb, A. %D 2022 %J Communications Earth & Environment %N 1 %P 320 %R doi:10.1038/s43247-022-00654-9 %T Global ocean wave fields show consistent regional trends between 1980 and 2014 in a multi-product ensemble %U https://doi.org/10.1038/s43247-022-00654-9 1 %X Historical trends in the direction and magnitude of ocean surface wave height, period, or direction are debated due to diverse data, time-periods, or methodologies. Using a consistent community-driven ensemble of global wave products, we quantify and establish regions with robust trends in global multivariate wave fields between 1980 and 2014. We find that about 30–40% of the global ocean experienced robust seasonal trends in mean and extreme wave height, period, and direction. Most of the Southern Hemisphere exhibited strong upward-trending wave heights (1–2 cm per year) and periods during winter and summer. Ocean basins with robust positive trends are far larger than those with negative trends. Historical trends calculated over shorter periods generally agree with satellite records but vary from product to product, with some showing a consistently negative bias. Variability in trends across products and time-periods highlights the importance of considering multiple sources when seeking robust change analyses. %0 journal article %@ 1814-9324 %A Zhang, Z., Wagner, S., Klockmann, M., Zorita, E. %D 2022 %J Climate of the Past %N 12 %P 2643-2668 %R doi:10.5194/cp-18-2643-2022 %T Evaluation of statistical climate reconstruction methods based on pseudoproxy experiments using linear and machine-learning methods %U https://doi.org/10.5194/cp-18-2643-2022 12 %X Three different climate field reconstruction (CFR) methods are employed to reconstruct spatially resolved North Atlantic–European (NAE) and Northern Hemisphere (NH) summer temperatures over the past millennium from proxy records. These are tested in the framework of pseudoproxy experiments derived from two climate simulations with comprehensive Earth system models. Two of these methods are traditional multivariate linear methods (principal component regression, PCR, and canonical correlation analysis, CCA), whereas the third method (bidirectional long short-term memory neural network, Bi-LSTM) belongs to the category of machine-learning methods. In contrast to PCR and CCA, Bi-LSTM does not need to assume a linear and temporally stable relationship between the underlying proxy network and the target climate field. In addition, Bi-LSTM naturally incorporates information about the serial correlation of the time series. Our working hypothesis is that the Bi-LSTM method will achieve a better reconstruction of the amplitude of past temperature variability. In all tests, the calibration period was set to the observational period, while the validation period was set to the pre-industrial centuries. All three methods tested herein achieve reasonable reconstruction performance on both spatial and temporal scales, with the exception of an overestimation of the interannual variance by PCR, which may be due to overfitting resulting from the rather short length of the calibration period and the large number of predictors. Generally, the reconstruction skill is higher in regions with denser proxy coverage, but it is also reasonably high in proxy-free areas due to climate teleconnections. All three CFR methodologies generally tend to more strongly underestimate the variability of spatially averaged temperature indices as more noise is introduced into the pseudoproxies. The Bi-LSTM method tested in our experiments using a limited calibration dataset shows relatively worse reconstruction skills compared to PCR and CCA, and therefore our working hypothesis that a more complex machine-learning method would provide better reconstructions for temperature fields was not confirmed. In this particular application with pseudoproxies, the implied link between proxies and climate fields is probably close to linear. However, a certain degree of reconstruction performance achieved by the nonlinear LSTM method shows that skill can be achieved even when using small samples with limited datasets, which indicates that Bi-LSTM can be a tool for exploring the suitability of nonlinear CFRs, especially in small data regimes. %0 journal article %@ 2662-4435 %A Daewel, U., Akhtar, N., Christiansen, N., Schrum, C. %D 2022 %J Communications Earth & Environment %N 1 %P 292 %R doi:10.1038/s43247-022-00625-0 %T Offshore wind farms are projected to impact primary production and bottom water deoxygenation in the North Sea %U https://doi.org/10.1038/s43247-022-00625-0 1 %X The wind wake effect of offshore wind farms affects the hydrodynamical conditions in the ocean, which has been hypothesized to impact marine primary production. So far only little is known about the ecosystem response to wind wakes under the premisses of large offshore wind farm clusters. Here we show, via numerical modeling, that the associated wind wakes in the North Sea provoke large-scale changes in annual primary production with local changes of up to ±10% not only at the offshore wind farm clusters, but also distributed over a wider region. The model also projects an increase in sediment carbon in deeper areas of the southern North Sea due to reduced current velocities, and decreased dissolved oxygen inside an area with already low oxygen concentration. Our results provide evidence that the ongoing offshore wind farm developments can have a substantial impact on the structuring of coastal marine ecosystems on basin scales. %0 journal article %@ 2073-4441 %A Mikheeva, E., Bieser, J., Schrum, C. %D 2022 %J Water %N 23 %P 3952 %R doi:10.3390/w14233952 %T Hydrodynamic Impacts on the Fate of Polychlorinated Biphenyl 153 in the Marine Environment %U https://doi.org/10.3390/w14233952 23 %X Due to their long half-life, polychlorinated biphenyls (PCBs) tend to contaminate not only coastal areas, but they travel over long distances, eventually reaching remote areas such the Arctic. The physical and biogeochemical features of every coastal area govern the main distribution patterns of freshly introduced PCBs into the marine system. Some of these processes are determined by chemical properties of the individual PCB congener. Thus, atmospheric influx along with ad/absorption on non-living organic material, photolytical and biological degradation processes vary from one PCB congener to another. For a detailed fate analysis of individual congeners, we developed a new chemical model, based on the GOTM-ECOSMO-FABM model framework. Here, we exemplarily present results for PCB153 based on 1D simulations of four regions in the North-Baltic Sea. The study area is characterized by different hydrodynamic and biogeochemical conditions. We investigate the impact of resuspension, mixing and the biological pump, sea ice and tides on the final phasal distribution of PCB153. Different combinations of these factors lead to the development of different areas of PCB153 accumulation, with the formation of hotspot areas, and influence the total uptake and concentration of PCB153 in the water column. As a result, two major dynamics determine the fate of PCB153 in the coastal ocean: (i) Primary production leads to PCB153 being adsorbed by organic material. Partitioning to organic material and sedimentation of organic particles removes dissolved PCB153 from the surface ocean and increases atmospheric influx. (ii) Tidal-induced resuspension and mixing control the benthic–pelagic exchange of PCB153 and its distribution in the water column. Depending on the resuspension regime and stratification, sediments can become a permanent (Gotland Deep, the Baltic Sea) or seasonal sink for PCB153. In regions with seasonal stratification and high near bottom turbulence (Northern North Sea), resuspension events can lead to pronounced peaks in PCB153 concentrations and can therefore have a major impact on bioaccumulation. Under the conditions of permanent mixing and high bottom turbulence (Southern North Sea, Bothnian Bay), pollutants are hardly accumulating in sediments. %0 journal article %@ 1755-876X %A Grayek, S., Stanev, E., Pham, N., Bonaduce, A., Staneva, J. %D 2022 %J Journal of Operational Oceanography %N sup1: Copernicus Ocean State Report, issue 6 %P s110-s118 %R doi:10.1080/1755876X.2022.2095169 %T Consistent data set of coastal sea level: The synergy between tidal gauge data and numerical modelling %U https://doi.org/10.1080/1755876X.2022.2095169 sup1: Copernicus Ocean State Report, issue 6 %X The multiannual (1993–2020) variability of sea level in the Baltic Sea is reconstructed by applying a Kalman filter approach. This technique learns how to generate data sets with the same statistics as the training data set, which in the studied case was taken from the CMEMS Baltic MFC operational model. It is demonstrated that using tide gauge data and statistical characteristics of the Baltic Sea from the model enables the generation of a high-resolution reconstruction of the sea surface height. Results obtained in this study demonstrated that the reconstruction method offers comprehensive high-resolution estimates (space and time) of sea level variability in the Baltic Sea based on tide gauge observations with high temporal resolution (e.g. hourly). The approach represents a valuable extension to the existing observing capabilities from altimetry, which do not capture sub-daily variations of sea level (e.g. storm surges). At the same time, the method consumes only a small fraction of the computational resources required by an assimilative model with comparable temporal/spatial resolution. %0 journal article %@ 1755-876x %A Staneva, J., Ricker, M., Akpınar, A., Behrens, A., Giesen, R., von Schuckmann, K. %D 2022 %J Journal of Operational Oceanography %N sup1: Copernicus Ocean State Report, issue 6 %P s56-s64 %R doi:10.1080/1755876X.2022.2095169 %T Long-term interannual changes in extreme winds and waves in the Black Sea %U https://doi.org/10.1080/1755876X.2022.2095169 sup1: Copernicus Ocean State Report, issue 6 %X This study aims to analyse long-term interannual changes in extreme winds and waves in the Black Sea. Severe wave conditions from 1979 to 2020 are detected using the 99th percentile of the significant wave height (SWH). Long-term spatial wave statistics of the Black Sea are then obtained based on the annual trend of 99th percentile SWH and the number, lifetime, and intensity of extreme events occurring between 1979 and 2020. In addition, the variability of these extreme event characteristics is revealed. Wave reanalysis of the Black Sea is used to investigate intra-annual variation and long-term wave energy potential change. Wave power and wind statistics are shown for the Black Sea CMEMS multiyear products to identify the most suitable areas for wave energy exploitation and offshore wind power potential and to guide the safe and efficient design, installation and operation of marine energy sector assets. The results reveal that the average number of storm events is highest in the eastern basin. In contrast, the average lifetime reaches a maximum on the southwestern coast. Intensity peaks in the same region as the lifetime but is also high in the basin interior. Spatial mean extreme event analyses show a slight increase in event numbers and intensity but decreasing trends for the event lifetime and maximum area of storm events. In regions where wave conditions are strong, there have been increases in extremes relative to normal conditions in recent years. This can significantly affect designs. In terms of wave energy, mean wave power peaks in the southwestern area of the Black Sea. The wave power trend follows a pattern similar to that of the SWH with a pronounced east–west difference; its variation is higher, resulting in a coefficient of variation of ∼2.5. %0 journal article %@ 2045-2322 %A Akhtar, N., Geyer, B., Schrum, C. %D 2022 %J Scientific Reports %N 1 %P 18307 %R doi:10.1038/s41598-022-22868-9 %T Impacts of accelerating deployment of offshore windfarms on near-surface climate %U https://doi.org/10.1038/s41598-022-22868-9 1 %X The European Union has set the ambitious goal of becoming climate neutral by 2050, which has stimulated renewable energy production and accelerated the deployment of offshore wind energy in the North Sea. Here, a high-resolution regional climate model was used to investigate the impact on the sea surface climate of large-scale offshore wind farms that are proposed for the North Sea. The results show a significant reduction in the air-sea heat fluxes and a local, annual mean net cooling of the lower atmosphere in the wind farm areas down to more than 2.0 Wm−2, due to a decrease in 10 m wind speed and turbulent kinetic energy and an increase in low-level clouds. Mean surface winds decreased by approximately 1 ms−1 downstream of wind farms. Furthermore, an increase of approximately 5% in mean precipitation was found over the wind farm areas. At a seasonal timescale, these differences are higher during winter and autumn than in other seasons. Although the offshore wind farms reduce the heat transport from the ocean to the atmosphere in the region of large wind farms, the atmospheric layers below the hub height show an increase in temperature, which is on the order of up to 10% of the climate change signal at the end of the century, but it is much smaller than the interannual climate variability. In contrast, wind speed changes are larger than projected mean wind speed changes due to climate change. Our results suggest that the impacts of large clustered offshore wind farms should be considered in climate change impact studies. Moreover, the identified offshore windfarm impacts on the sea surface climate and the introduced spatial pattern in atmospheric conditions, in particular the modeled wind speed changes, suggest potential impacts on local ocean dynamics and the structure of the marine ecosystem. This should be considered in future scenarios for the North Sea marine environment and taken into account as a structuring influence in the offshore environment. %0 journal article %@ 2167-8359 %A Weinert, M., Kröncke, I., Meyer, J., Mathis, M., Pohlmann, T., Henning, R. %D 2022 %J PeerJ %P e14105 %R doi:10.7717/peerj.14105 %T Benthic ecosystem functioning under climate change: modelling the bioturbation potential for benthic key species in the southern North Sea %U https://doi.org/10.7717/peerj.14105 %X Climate change affects the marine environment on many levels with profound consequences for numerous biological, chemical, and physical processes. Benthic bioturbation is one of the most relevant and significant processes for benthic-pelagic coupling and biogeochemical fluxes in marine sediments, such as the uptake, transport, and remineralisation of organic carbon. However, only little is known about how climate change affects the distribution and intensity of benthic bioturbation of a shallow temperate shelf sea system such as the southern North Sea. In this study, we modelled and projected changes in bioturbation potential (BPp) under a continuous global warming scenario for seven southern North Sea key bioturbators: Abra alba, Amphiura filiformis, Callianassa subterranea, Echinocardium cordatum, Goniada maculata, Nephtys hombergii, and Nucula nitidosa. Spatial changes in species bioturbation intensity are simulated for the years 2050 and 2099 based on one species distribution model per species driven by bottom temperature and salinity changes using the IPCC SRES scenario A1B. Local mean bottom temperature was projected to increase between 0.15 and 5.4 °C, while mean bottom salinity was projected to moderately decrease by 1.7. Our results show that the considered benthic species are strongly influenced by the temperature increase. Although the total BP remained rather constant in the southern North Sea, the BPp for four out of seven species was projected to increase, mainly due to a simultaneous northward range expansion, while the BPp in the core area of the southern North Sea declined for the same species. Bioturbation of the most important species, Amphiura filiformis and Echinocardium cordatum, showed no substantial change in the spatial distribution, but over time. The BPp of E. cordatum remained almost constant until 2099, while the BPp of A. filiformis decreased by 41%. The northward expansion of some species and the decline of most species in the south led to a change of relative contribution to bioturbation in the southern North Sea. These results indicate that some of the selected key bioturbators in the southern North Sea might partly compensate the decrease in bioturbation by others. But especially in the depositional areas where bioturbation plays a specifically important role for ecosystem functioning, bioturbation potential declined until 2099, which might affect the biochemical cycling in sediments of some areas of the southern North Sea. %0 journal article %@ 2772-4115 %A Sánchez-Arcilla, A., Cáceres, I., Le Roux, X., Hinkel, J., Schuerch, M., Nicholls, R., Otero, d., Staneva, J., de Vries, M., Pernice, U., Briere, C., Caiola, N., Gracia, V., Ibáñez, C., Torresan, S. %D 2022 %J Nature-Based Solutions %P 100032 %R doi:10.1016/j.nbsj.2022.100032 %T Barriers and enablers for upscaling coastal restoration %U https://doi.org/10.1016/j.nbsj.2022.100032 %X Coastal restoration is often distrusted and, at best, implemented at small scales, which hampers its potential for coastal adaptation. Present technical, economic and management barriers stem from sectoral and poorly coordinated local interventions, which are insufficiently monitored and maintained, precluding the upscaling required to build up confidence in ecosystem restoration. The paper posits that there is enough knowledge, technology, financial and governance capabilities for increasing the pace and scale of restoration, before the onset of irreversible coastal degradation. We propose a systemic restoration, which integrates Nature based Solutions (NbS) building blocks, to provide climate-resilient ecosystem services and improved biodiversity to curb coastal degradation. The result should be a reduction of coastal risks from a decarbonised coastal protection, which at the same time increases coastal blue carbon. We discuss barriers and enablers for coastal adaptation-through-restoration plans, based on vulnerable coastal archetypes, such as deltas, estuaries, lagoons and coastal bays. These plans, based on connectivity and accommodation space, result in enhanced resilience and biodiversity under increasing climatic and human pressures. The paper concludes with a review of the interconnections between the technical, financial and governance dimensions of restoration, and discusses how to fill the present implementation gap. %0 journal article %@ 2296-7745 %A Arlinghaus, P., Zhang, W., Schrum, C. %D 2022 %J Frontiers in Marine Science %P 1011760 %R doi:10.3389/fmars.2022.1011760 %T Small-scale benthic faunal activities may lead to large-scale morphological change- A model based assessment %U https://doi.org/10.3389/fmars.2022.1011760 %X A novel 3-dimensional numerical model resolving dynamic interactions between environmental drivers and benthic fauna was applied to an idealized domain as analogous to typical tidal embayments. The aim is to derive insights into the role of benthic fauna in guiding long-term (decadal to centennial) coastal morphological evolution at a system scale. Three major functions by benthic fauna on sediment dynamics, namely bio-destabilization, bio-deposition and bio-stabilization, were incorporated. Results indicate that each of the three functions is able to guide a unique and profound long-term change of the embayment morphology. Bioturbation-induced sediment mixing and bio-destabilization may result in net sediment export out of the embayment, whilst bio-deposition and bio-stabilization tend to alter the embayment toward a net sediment import environment. Benthic fauna is able to modify large-scale hydro-morphology toward a state favorable for living. A combined effect of the three functions is not just a simple neutralization of the opposing impacts between sediment stabilization and destabilization. Rather, it leads to a unique response of the embayment morphology due to interactions between different benthic functional groups. Comparison with a real tidal embayment (Jade Bay from the Wadden Sea) justified a general validity of the model results in terms of statistics in both morphology and benthic fauna, and suggested an equal importance of interactions between benthic fauna and bed morphology and between different benthic functional groups in guiding morphological development of complex coastal systems. %0 journal article %@ 2296-7745 %A Sguotti, C., Blöcker, A., Färber, L., Blanz, B., Cormier, R., Diekmann, R., Letschert, J., Rambo, H., Stollberg, N., Stelzenmüller, V., Stier, A., Möllmann, C. %D 2022 %J Frontiers in Marine Science %P 945204 %R doi:10.3389/fmars.2022.945204 %T Irreversibility of regime shifts in the North Sea %U https://doi.org/10.3389/fmars.2022.945204 %X Human impacts can induce ecosystems to cross tipping points and hence unexpected and sudden changes in ecosystem services that are difficult or impossible to reverse. The world´s oceans suffer from cumulative anthropogenic pressures like overexploitation and climate change and are especially vulnerable to such regime shifts. Yet an outstanding question is whether regime changes in marine ecosystems are irreversible. Here we first review the evidence for regime shifts in the North Sea ecosystem, one of the heaviest impacted and best studied marine ecosystems in the world. We then used catastrophe theory to show that fishing and warming have caused a previously undetected and potentially irreversible regime shift. Our study emphasizes the combined effects of local and global human impacts in driving significant ecosystem shifts and suggests that adaptation is likely the central avenue forward for maintaining services in the face of global climate change. %0 journal article %@ 0025-3162 %A Garcia-Oliva, O., Wirtz, K. %D 2022 %J Marine Biology %N 9 %P 122 %R doi:10.1007/s00227-022-04102-2 %T Size-dependent and -independent prey selection of dinoflagellates %U https://doi.org/10.1007/s00227-022-04102-2 9 %X Mechanisticapproachestoplanktonfood-websoftenrelyonsize-basedmodels.Thesemodelsdescribe predator–preyrelationshipsbasedonpredator body or cell size. However, size-based representations of trophic relationships fail to encompass the diverse feeding behavior of dinoflagellates, which play an essential role in the food-web due to their abundance and ubiquity. Here, we introduce the specialization factor (s) as an effective trait, which aggregates over aspects of morphology, trophic strategy, and feeding behavior and quantifies the degree of specialization towards a specific prey size. We found that specialization to either the upper or lower edge of the prey size spectrum is connected to size independent trophic relations. As a result, dinoflagellates can be divided into three groups with distinct dependencies of optimal prey size on predator size: (1) mixotrophic engulfers specialized on small prey (s=−1), (2) pallium feeders on large prey (s=1), and (3) neutral feeders (s=0) encompassing generalist engulfers and tube feeders. Our trait based approach elucidates the evolutionary significance of diverse feeding modes and specialization in dinoflagellates compared to phylogenetically older groups such as ciliates. It furthermore leads to a more accurate representation of trophic relationships of dinoflagellates in models and can provide, more generally, an efficient description of complex and diverse feeding relations in plankton food-webs. %0 journal article %@ 1758-678X %A Wirtz, K., Smith, S., Mathis, M., Taucher, J. %D 2022 %J Nature Climate Change %N 8 %P 750-756 %R doi:10.1038/s41558-022-01430-5 %T Vertically migrating phytoplankton fuel high oceanic primary production %U https://doi.org/10.1038/s41558-022-01430-5 8 %X Marine net primary production (NPP) is remarkably high given the typical vertical separation of 50–150 m between the depth zones of light and nutrient sufficiency, respectively. Here we present evidence that many autotrophs bridge this gap through downward and upward migration, thereby facilitating biological nutrient pumping and high rates of oceanic NPP. Our model suggests that phytoplankton vertical migration (PVM) fuels up to 40% (>28 tg yr−1 N) of new production and directly contributes 25% of total oceanic NPP (herein estimated at 56 PgC yr−1). Confidence in these estimates is supported by good reproduction of seasonal, vertical and geographic variations in NPP. In contrast to common predictions, a sensitivity study of the PVM model indicates higher NPP under global warming when enhanced stratification reduces physical nutrient transport into the surface ocean. Our findings suggest that PVM is a key mechanism driving marine biogeochemistry and therefore requires consideration in global carbon budgets. %0 journal article %@ 0253-505X %A Ye, Q., Yang, Z., Bao, M., Shi, W., Shi, H., You, Z., Zhang, W. %D 2022 %J Acta Oceanologica Sinica %N 5 %P 163-172 %R doi:10.1007/s13131-021-1859-2 %T Distribution characteristics of wave energy in the Zhe-Min coastal area %U https://doi.org/10.1007/s13131-021-1859-2 5 %X A 10-year (2003–2012) hindcast was conducted to study the wave field in the Zhe-Min coastal area (Key Area OE-W2) located off Zhejiang and Fujian provinces of China. Forced by the wind field from a weather research and forecasting model (WRF), high-resolution wave modelling using the SWAN was carried out in the study area. The simulated wave fields show a good agreement with observations. Using the simulation results, we conducted statistical analysis of wave power density in terms of spatial distribution and temporal variation. The effective duration of wave energy in the sea area was discussed, and the stability of wave energy was evaluated using the coefficient of variation of wave power density. Results indicate that the wave energy resource in the study area was about 4.11×106 kW. The distribution of wave energy tends to increase from the north (off Zhejiang coast) to the south (off Fujian coast), and from near-shore area to the open sea. The sea areas with wave power density greater than 2 kW/m are mostly distributed seaward of the 10-m isobath, and the contours of the wave power density are almost parallel to the shoreline. The sea areas around the islands that are far from the mainland are rich in wave energy, usually more than 6 kW/m, and therefore are of obvious advantages in planning wave energy development and utilization. The effective duration of wave energy in the offshore area shows an increasing trend from north (off Zhejiang coast) to south (off Fujian coast), with values of ∼3 500 h in the north and ∼4 450 h in the south. The coefficient of variation of wave energy in this region is mostly in the range of 1.5–3.0, and gradually decreases from the north to the south, suggesting that the wave energy in the south is more stable than that in the north. %0 journal article %@ 2352-4855 %A Leung, K., Khim, J., Staneva, J. %D 2022 %J Regional Studies in Marine Science %P 102577 %R doi:10.1016/j.rsma.2022.102577 %T A time for rejuvenation of the journal after the first seven years %U https://doi.org/10.1016/j.rsma.2022.102577 %X No Abstract %0 journal article %@ 0022-3670 %A Behr, L., Luther, N., Josey, S.A., Luterbacher, J., Wagner, S., Xoplaki, E. %D 2022 %J Journal of Physical Oceanography %N 7 %P 1397-1413 %R doi:10.1175/JPO-D-21-0082.1 %T On the Representation of Mediterranean Overflow Waters in Global Climate Models %U https://doi.org/10.1175/JPO-D-21-0082.1 7 %X Accurate representation of the Atlantic–Mediterranean exchange in climate models is important for a reliable simulation of the circulation in the North Atlantic Ocean. We evaluate the performance of 10 global climate models in representing Mediterranean Overflow Water (MOW) over the recent period 1986–2005 by using various performance metrics. The metrics are based on the representation of the climatological mean state and the spatiotemporal variability of temperature, salinity, and volume transports. On the basis of analyses and observations, we perform a model ranking by calculating absolute, relative, and total relative errors Ej over each performance metric and model. The majority of models simulate at least six metrics well. The equilibrium depth of the MOW, the mean Atlantic–Mediterranean exchange flow, and the dominant pattern of the MOW are represented reasonably well by most of the models. Of those models considered, MPI-ESM-MR, MPI-ESM-LR, CSIRO Mk3.6.0, and MRI-CGCM3 provide the best MOW representation (Ej = 0.14, 0.19, 0.19, and 0.25, respectively). They are thus likely to be the most suitable choices for studies of MOW-dependent processes. However, the models experience salinity, temperature, and transport biases and do not represent temporal variability accurately. The implications of our results for future model analysis of the Mediterranean Sea overflow are discussed. %0 journal article %@ 2296-7745 %A Meng, Q., Zhou, F., Ma, X., Xuan, J., Zhang, H., Wang, S., Ni, Z., Zhang, W., Wang, B., Li, D., Tian, D., Li, J., Zeng, C., Chen, J., Huang, D. %D 2022 %J Frontiers in Marine Science %P 892797 %R doi:10.3389/fmars.2022.892797 %T Response Process of Coastal Hypoxia to a Passing Typhoon in the East China Sea %U https://doi.org/10.3389/fmars.2022.892797 %X Details of the development of coastal hypoxia in response to the passage of Typhoon Bavi (2020) in the East China Sea were reconstructed by numerical modeling using a three-dimensional coupled physical–biogeochemical model. The model was validated via repeated surveys along a transect across a submerged river valley off the Changjiang Estuary before and after the passage of Typhoon Bavi. Before Bavi’s arrival, survey data indicated that the coastal hypoxia had formed off the Changjiang Estuary. However, the hypoxia was not eliminated but instead migrated and aggravated along the observed transect after the typhoon passage. This phenomenon cannot be attributed to the typhoon-induced mixing. Simulation results reveal that the observed development and spatial migration of hypoxia was mainly controlled by typhoon-induced oceanic advection. Results show that Bavi stimulated a regional quasi-barotropic cyclonic loop circulation and coastal downwelling reversing general summer circulation patterns. The onshore transport of the warmer shelf water and subsequent downwelling resulted in a warming of coastal water. The southward coastal current and downwelling induced by the typhoon also led to a migration of the hypoxic zone. Meanwhile, a massive transport of resuspended planktonic detritus from the steep inner shelf and the shallow Changjiang bank toward the submerged river valley occurred. This study reveals that the typhoon-driven currents can play an important role in the development of hypoxia and redistribution of deposited organic matter in coastal shelf seas, which may have both short- and long-term effects on the regional marine biogeochemical environment. %0 journal article %@ 0309-1708 %A Kumar, A., Gosling, S.N., Johnson, M.F., Jones, M.D., Zaherpour, J., Kumar, R., Leng, G., Schmied, H.M., Kupzig, J., Breuer, L., Hanasaki, N., Tang, Q., Ostberg, S., Stacke, T., Pokhrel, Y., Wada, Y., Masaki, Y. %D 2022 %J Advances in Water Resources %P 104212 %R doi:10.1016/j.advwatres.2022.104212 %T Multi-model evaluation of catchment- and global-scale hydrological model simulations of drought characteristics across eight large river catchments %U https://doi.org/10.1016/j.advwatres.2022.104212 %X Although global- and catchment-scale hydrological models are often shown to accurately simulate long-term runoff time-series, far less is known about their suitability for capturing hydrological extremes, such as droughts. Here we evaluated simulations of hydrological droughts from nine catchment scale hydrological models (CHMs) and eight global scale hydrological models (GHMs) for eight large catchments: Upper Amazon, Lena, Upper Mississippi, Upper Niger, Rhine, Tagus, Upper Yangtze and Upper Yellow. The simulations were conducted within the framework of phase 2a of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP2a). We evaluated the ability of the CHMs, GHMs and their respective ensemble means (Ens-CHM and Ens-GHM) to simulate observed hydrological droughts of at least one month duration, over 31 years (1971–2001). Hydrological drought events were identified from runoff-deficits and the Standardised Runoff Index (SRI). In all catchments, the CHMs performed relatively better than the GHMs, for simulating monthly runoff-deficits. The number of drought events identified under different drought categories (i.e. SRI values of -1 to -1.49, -1.5 to -1.99, and ≤-2) varied significantly between models. All the models, as well as the two ensemble means, have limited abilities to accurately simulate drought events in all eight catchments, in terms of their occurrence and magnitude. Overall, there are opportunities to improve both CHMs and GHMs for better characterisation of hydrological droughts. %0 journal article %@ 2073-4433 %A Schwarzkopf, D., Petrik, R., Matthias, V., Quante, M., Yu, G., Zhang, Y. %D 2022 %J Atmosphere %N 6 %P 894 %R doi:10.3390/atmos13060894 %T Comparison of the Impact of Ship Emissions in Northern Europe and Eastern China %U https://doi.org/10.3390/atmos13060894 6 %X It is well known that ship emissions contribute significantly to atmospheric pollution. However, the impact on air quality can regionally vary, as influenced by parameters such as the composition of the regional shipping fleet, state of background atmospheric pollution, and meteorological aspects. This study compared two regions with high shipping densities in 2015. These include the North and Baltic Seas in Europe and the Yellow and East China Seas in China. Here, a key focal point is an evaluation of differences and similarities of the impacts of ship emissions under different environmental conditions, particularly between regions with medium (Europe) and high air pollution (China). To assess this, two similarly performed chemical transport model runs were carried out with highly resolved bottom-up ship emission inventories for northern Europe and China, calculated with the recently developed MoSES model, publicly available emissions data for nonshipping sources (EDGAR, MEIC). The performance of the model was evaluated against measurement data recorded at coastal stations. Annual averages at affected coastal regions for NO2, SO2, O3 and PM2.5 were modeled in Europe to be 3, below 0.3, 2.5, 1 and in China 3, 2, 2–8, 1.5, respectively, all given in μg/m3. In highly affected regions, such as large harbors, the contributions of ship-related emissions modeled in Europe were 15%, 0.3%, −12.5%, 1.25% and in China were 15%, 6%, −7.5%, 2%, respectively. Absolute pollutant concentrations from ships were modeled slightly higher in China than in Europe, albeit the relative impact was smaller in China due to higher emissions from other sectors. The different climate zones of China and the higher level of atmospheric pollution were found to seasonally alter the chemical transformation processes of ship emissions. Especially in northern China, high PM concentrations during winter were found to regionally inhibit the transformation of ship exhausts to secondary PM, and reduce the impact of ship-related aerosols, compared to Europe. %0 journal article %@ 1561-8633 %A Meyer, E., Weisse, R., Grabemann, I., Tinz, B., Scholz, R. %D 2022 %J Natural Hazards and Earth System Sciences %N 7 %P 2419-2432 %R doi:10.5194/nhess-22-2419-2022 %T Reconstruction of wind and surge of the 1906 storm tide at the German North Sea coast %U https://doi.org/10.5194/nhess-22-2419-2022 7 %X Storm tides represent a major threat to the low-lying German North Sea coast. Knowledge of extremes is essential for the design of reliable and robust coastal defences. A storm tide that occurred on 12–13 March 1906 along the German Bight coastline still represents one of the strongest events on record. For this event, detailed knowledge of atmospheric and hydrodynamic conditions is still lacking. To assess the potential impact of such an event on today's coastline, century-long atmospheric reanalysis data together with a manual synoptic reconstruction based on archived weather data were used to drive a tide-surge model and to simulate water levels during the event. Sensitivity experiments were performed to estimate potential amplification of water levels that could have been caused by different time lags between the storm and the astronomical tide. Comparison between the model results and the limited available observational data indicated that the water levels could be reasonably reconstructed using wind fields from the manual synoptic approach and some of the reanalysis ensemble members. The amplification potential was found to be low because the storm occurred during spring tide and shifts in the phase of the astronomic tide yielded only small changes in total water levels. To summarise, if pressure data are available at relevant locations, historical storm surges can be simulated with reanalysis products and also with a manual synoptic reconstruction. %0 journal article %@ 2169-9275 %A Stanev, E., Wahle, K., Staneva, J. %D 2022 %J Journal of Geophysical Research : Oceans %N 8 %P e2021JC018012 %R doi:10.1029/2021JC018012 %T The Synergy of Data From Profiling Floats, Machine Learning and Numerical Modeling: Case of the Black Sea Euphotic Zone %U https://doi.org/10.1029/2021JC018012 8 %X Data from profiling floats in the Black Sea revealed complex temporal and spatial relationships between physical variables and oxygen, chlorophyll and the backscattering coefficient at 700 nm, as well as some limits in understanding the details of biogeochemistry dynamics. To account for different interdependences between physical and biogeochemical properties, a feedforward backpropagation neural network (NN) was used. This NN learns from data recorded by profiling floats and predicts biogeochemical states using physical measurements only. The performance was very high, particularly for oxygen, but it decreased when the NN was applied to older data because the interrelationships between the physical and biogeochemical properties have changed recently. The biogeochemical states reconstructed by the NN using physical data produced by a coupled physical–biogeochemical operational model were better than the biogeochemical outputs of the same coupled model. Therefore, the use of data from profiling floats, physical properties from numerical models and NNs appears to be a powerful approach for reconstructing the 4D dynamics of the euphotic zone. Basin-wide patterns and temporal variabilities in oxygen, backscattering coefficient and chlorophyll were also analyzed. Of particular interest is the reconstruction of short-lived biogeochemical features, particularly in coastal anticyclone areas, which are difficult to observe with available floats at the basin scale. %0 journal article %@ 1942-2466 %A Mathis, M., Logemann, K., Maerz, J., Lacroix, F., Hagemann, S., Chegini, F., Ramme, L., Ilyina, T., Korn, P., Schrum, C. %D 2022 %J Journal of Advances in Modeling Earth Systems : JAMES %N 8 %P e2021MS002789 %R doi:10.1029/2021MS002789 %T Seamless Integration of the Coastal Ocean in Global Marine Carbon Cycle Modeling %U https://doi.org/10.1029/2021MS002789 8 %X We present the first global ocean-biogeochemistry model that uses a telescoping high resolution for an improved representation of coastal carbon dynamics: ICON-Coast. Based on the unstructured triangular grid topology of the model, we globally apply a grid refinement in the land-ocean transition zone to better resolve the complex circulation of shallow shelves and marginal seas as well as ocean-shelf exchange. Moreover, we incorporate tidal currents including bottom drag effects, and extend the parameterizations of the model's biogeochemistry component to account explicitly for key shelf-specific carbon transformation processes. These comprise sediment resuspension, temperature-dependent remineralization in the water column and sediment, riverine matter fluxes from land including terrestrial organic carbon, and variable sinking speed of aggregated particulate matter. The combination of regional grid refinement and enhanced process representation enables for the first time a seamless incorporation of the global coastal ocean in model-based Earth system research. In particular, ICON-Coast encompasses all coastal areas around the globe within a single, consistent ocean-biogeochemistry model, thus naturally accounting for two-way coupling of ocean-shelf feedback mechanisms at the global scale. The high quality of the model results as well as the efficiency in computational cost and storage requirements proves this strategy a pioneering approach for global high-resolution modeling. We conclude that ICON-Coast represents a new tool to deepen our mechanistic understanding of the role of the land-ocean transition zone in the global carbon cycle, and to narrow related uncertainties in global future projections. %0 journal article %@ 0048-9697 %A Pillai, U., Pinardi, N., Alessandri, J., Federico, I., Causio, S., Unguendoli, S., Valentini, A., Staneva, J. %D 2022 %J Science of the Total Environment %P 157603 %R doi:10.1016/j.scitotenv.2022.157603 %T A Digital Twin modelling framework for the assessment of seagrass Nature Based Solutions against storm surges %U https://doi.org/10.1016/j.scitotenv.2022.157603 %X This Digital Twin modelling framework allows us to answer “what if” scenario questions such as: (i) are indigenous seagrass meadows able to reduce the energy of storm surges, and if so how? (ii) what are the best seagrass types and their landscaping for optimal wave and current attenuation? An important result of the study is to show that the landscaping of seagrasses is an important design choice and that seagrass does not directly attenuate the sea level but the current amplitudes. This framework reveals the link between seagrass NBS and the components of the disruptive potential of storm surges (waves and sea level) and opens up new avenues for future studies. %0 journal article %@ 2049-6060 %A Paasche, H., Gross, M., Lüttgau, J., Greenberg, D., Weigel, T. %D 2022 %J Geoscience Data Journal %N 2 %P 393-399 %R doi:10.1002/gdj3.132 %T To the brave scientists: Aren't we strong enough to stand (and profit from) uncertainty in Earth system measurement and modelling? %U https://doi.org/10.1002/gdj3.132 2 %X The current handling of data in earth observation, modelling and prediction measures gives cause for critical consideration, since we all too often carelessly ignore data uncertainty. We think that Earth scientists are generally aware of the importance of linking data to quantitative uncertainty measures. But we also think that uncertainty quantification of Earth observation data too often fails at very early stages. We claim that data acquisition without uncertainty quantification is not sustainable and machine learning and computational modelling cannot unfold their potential when analysing complex natural systems like the Earth. Current approaches such as stochastic perturbation of parameters or initial conditions cannot quantify uncertainty or bias arising from the choice of model, limiting scientific progress. We need incentives stimulating the honest treatment of uncertainty starting during data acquisition, continuing through analysis methodology and prediction results. Computational modellers and machine learning experts have a critical role, since they enjoy high esteem from stakeholders and their methodologies and their results critically depend on data uncertainty. If both want to advance their uncertainty assessment of models and predictions of complex systems like the Earth, they have a common problem to solve. Together, computational modellers and machine learners could develop new strategies for bias identification and uncertainty quantification offering a more all-embracing uncertainty quantification than any known methodology. But since it starts for computational modellers and machine learners with data and their uncertainty, the fundamental first step in such a development would be leveraging shareholder esteem to insistently advocate for reduction of ignorance when it comes to uncertainty quantification of data. %0 journal article %@ 2225-1154 %A Yi, X., Hünicke, B., Zorita, E. %D 2021 %J Climate %N 5 %P 72 %R doi:10.3390/cli9050072 %T Evolution of the Arabian Sea Upwelling from the Last Millennium to the Future as Simulated by Earth System Models %U https://doi.org/10.3390/cli9050072 5 %X Arabian Sea upwelling in the past has been generally studied based on the sediment records. We apply two earth system models and analyze the simulated water vertical velocity to investigate coastal upwelling in the western Arabian Sea over the last millennium. In addition, two models with slightly different configurations are also employed to study the upwelling in the 21st century under the strongest and the weakest greenhouse gas emission scenarios. With a negative long-term trend caused by the orbital forcing of the models, the upwelling over the last millennium is found to be closely correlated with the sea surface temperature, the Indian summer Monsoon and the sediment records. The future upwelling under the Representative Concentration Pathway (RCP) 8.5 scenario reveals a negative trend, in contrast with the positive trend displayed by the upwelling favorable along-shore winds. Therefore, it is likely that other factors, like water stratification in the upper ocean layers caused by the stronger surface warming, overrides the effect from the upwelling favorable wind. No significant trend is found for the upwelling under the RCP2.6 scenario, which is likely due to a compensation between the opposing effects of the increase in upwelling favorable winds and the water stratification. %0 journal article %@ 1752-0894 %A Büntgen, U., Urban, O., Krusic, P.J., Rybníček, M., Kolář, T., Kyncl, T., Ač, A., Koňasová, E., Čáslavský, J., Esper, J., Wagner, S., Saurer, M., Tegel, W., Dobrovolný, P., Cherubini, P., Reinig, F., Trnka, M. %D 2021 %J Nature Geoscience %N 4 %P 190-196 %R doi:10.1038/s41561-021-00698-0 %T Recent European drought extremes beyond Common Era background variability %U https://doi.org/10.1038/s41561-021-00698-0 4 %X Europe’s recent summer droughts have had devastating ecological and economic consequences, but the severity and cause of these extremes remain unclear. Here we present 27,080 annually resolved and absolutely dated measurements of tree-ring stable carbon and oxygen (δ13C and δ18O) isotopes from 21 living and 126 relict oaks (Quercus spp.) used to reconstruct central European summer hydroclimate from 75 bce to 2018 ce. We find that the combined inverse δ13C and δ18O values correlate with the June–August Palmer Drought Severity Index from 1901–2018 at 0.73 (P < 0.001). Pluvials around 200, 720 and 1100 ce, and droughts around 40, 590, 950 and 1510 ce and in the twenty-first century, are superimposed on a multi-millennial drying trend. Our reconstruction demonstrates that the sequence of recent European summer droughts since 2015 ce is unprecedented in the past 2,110 years. This hydroclimatic anomaly is probably caused by anthropogenic warming and associated changes in the position of the summer jet stream. %0 journal article %@ 1674-9278 %A von Storch, H., Geyer, B., Li, Y., Matthias, V., Rockel, B. %D 2021 %J Advances in Climate Change Research %N 5 %P 677-685 %R doi:10.1016/j.accre.2021.03.003 %T Chinese lockdown as aerosol reduction experiment %U https://doi.org/10.1016/j.accre.2021.03.003 5 %X The lockdown of large parts of Chinese economy beginning in late January 2020 lead to significant regional changes of aerosol loads, which suggests a reduction of backscatter and consequently a regional warming in the following months. Using local data and a numerical experiment with a limited area model, we have examined how strong this response may have been. The observed (local and reanalysis) observations point to a warming of less than 1.0 K, the simulations to a warming of the order of 0.5 K. These numbers are uncertain, because of large-scale natural variability and an ad-hoc choice of aerosol optical depth anomaly in the simulation. Thus, the result was, in short, that there was actually a weak warming of a few tenth of degrees, while noteworthy changes in circulation or in precipitation were not detected. More specifically, we found that at selected central China stations temperatures were found to be higher than in previous two years. This warming goes with a marked diurnal signal, with a maximum warming in the early afternoon (06 UTC), weakest at night (18 UTC). This may be related to a general warming of large swaths of Asia (including Siberia, which is not related to local aerosol forcing). Indeed, also the stations outside the immediate strong lockdown region are showing warming, albeit a weaker one. Thus, the difference 2020 minus 2019/2018 may overestimate the effect. The ad-hoc series of numerical experiments indicates that the simulated changes are robust and suffer little from internal dynamical variability. In particular, the overall reduction of the aerosol optical depth does not lead to phases of larger intermittent divergence among the model simulations, irrespective of the aerosol load. Instead, the simulations with reduced anthropogenic aerosol load show more a mere locally increased temperature. This may indicate that the aerosol effect is mostly thermodynamic in all local air columns in the region. %0 journal article %@ 0171-8630 %A Skogen, M., Ji, R., Akimova, A., Daewel, U., Hansen, C., Hjøllo, S., van Leeuwen, S., Maar, M., Macias, D., Mousing, E., Almroth-Rosell, E., Sailley, S., Spence, M., Troost, T., Wolfshaar, K. %D 2021 %J Marine Ecology Progress Series %P 7-13 %R doi:10.3354/meps13574 %T Disclosing the truth: Are models better than observations? %U https://doi.org/10.3354/meps13574 %X The aphorism, ‘All models are wrong, but some models are useful’, originally referred to statistical models, but is now used for scientific models in general. When presenting results from a marine simulation model, this statement effectively stops discussions about the quality of the model, as there is always another observation to mismatch, and thereby another confirmation why the model cannot be trusted. It is common that observations are less challenged and are often viewed as a ‘gold standard’ for judging models, whereas proper interpretations and the true value of models are often overlooked. Models are not perfect, and there are many examples where models are used improperly to provide misleading answers with great confidence, but to what extent does an observation represent the truth? The precision of the observational gear may be high, but what about representativeness? The interpretation of observations is simply another model, but this time not coded in a computer language but rather formed by the individual observer. We submit that it would be more productive to initiate a process where the norm is that models and observations are joined to strengthen both. In the end, neither method is the goal, but both are useful tools for disclosing the truth. Biased views on either observational or modeling approaches would limit us from achieving this goal. %0 journal article %@ 2169-9275 %A Chen, W., Schulz-Stellenfleth, J., Grayek, S., Staneva, J. %D 2021 %J Journal of Geophysical Research : Oceans %N 5 %P e2020JC017059 %R doi:10.1029/2020JC017059 %T Impacts of the Assimilation of Satellite Sea Surface Temperature Data on Volume and Heat Budget Estimates for the North Sea %U https://doi.org/10.1029/2020JC017059 5 %X Mechanisms controlling the heat budget of the North Sea are investigated based on a combination of satellite sea surface temperature measurements and numerical model simulations. Lateral heat fluxes across the shelf edge and into the Baltic Sea as well as vertical ocean-atmosphere heat exchange are considered. A 3-D variational (3DVAR) data assimilation (DA) scheme is applied, which contains assumed model error correlations that depend on the mixed layer depth derived from a coupled circulation/ocean wave model. The analysis balances pressure gradients introduced by temperature modifications. Significant hydrodynamic model response to DA was found, which should be considered in the heat budget estimations. The observed change of the current velocity field decreases the lateral advective volume/heat exchanges between the North Sea and the Atlantic, yielding an increased heat flux from the Atlantic into the North Sea and more heat flux from the sea to the atmosphere. The largest DA impact on volume/heat transport is in the Norwegian Channel, where the dominant process is Eulerian transport, followed by tidal pumping and wind pumping. Further analysis reveals an acceleration of the along-shelf current at the northern edge of the North Sea, a decrease in the horizontal pressure gradient from the Atlantic to the North Sea, and a reduction of the Eulerian transport of volume/heat outward the North Sea. Furthermore, the coupling between the circulation model and the wave model has significant impacts on lateral heat advection in the DA run, which is due to the wave impact on the mixed layer depth. %0 journal article %@ 2296-7745 %A Friedland, R., Macias, D., Cossarini, G., Daewel, U., Estournel, C., Garcia-Gorriz, E., Grizzetti, B., Grégoire, M., Gustafson, B., Kalaroni, S., Kerimoglu, O., Lazzari, P., Lenhart, H., Lessin, G., Maljutenko, I., Miladinova, S., Müller-Karulis, B., Neumann, T., Parn, O., Pätsch, J., Piroddi, C., Raudsepp, U., Schrum, C., Stegert, C., Stips, A., Tsiaras, K., Ulses, C., Vandenbulcke, L. %D 2021 %J Frontiers in Marine Science %P 596126 %R doi:10.3389/fmars.2021.596126 %T Effects of Nutrient Management Scenarios on Marine Eutrophication Indicators: A Pan-European, Multi-Model Assessment in Support of the Marine Strategy Framework Directive %U https://doi.org/10.3389/fmars.2021.596126 %X A novel pan-European marine model ensemble was established, covering nearly all seas under the regulation of the Marine Strategy Framework Directive (MSFD), with the aim of providing a consistent assessment of the potential impacts of riverine nutrient reduction scenarios on marine eutrophication indicators. For each sea region, up to five coupled biogeochemical models from institutes all over Europe were brought together for the first time. All model systems followed a harmonised scenario approach and ran two simulations, which varied only in the riverine nutrient inputs. The load reductions were evaluated with the catchment model GREEN and represented the impacts due to improved management of agriculture and wastewater treatment in all European river systems. The model ensemble, comprising 15 members, was used to assess changes to the core eutrophication indicators as defined within MSFD Descriptor 5. In nearly all marine regions, riverine load reductions led to reduced nutrient concentrations in the marine environment. However, regionally the nutrient input reductions led to an increase in the non-limiting nutrient in the water, especially in the case of phosphate concentrations in the Black Sea. Further core eutrophication indicators, such as chlorophyll-a, bottom oxygen and the Trophic Index TRIX, improved nearly everywhere, but the changes were less pronounced than for the inorganic nutrients. The model ensemble displayed strong consistency and robustness, as most if not all models indicated improvements in the same areas. There were substantial differences between the individual seas in the speed of response to the reduced nutrient loads. In the North Sea ensemble, a stable plateau was reached after only three years, while the simulation period of eight years was too short to obtain steady model results in the Baltic Sea. The ensemble exercise confirmed the importance of improved management of agriculture and wastewater treatments in the river catchments to reduce marine eutrophication. Several shortcomings were identified, the outcome of different approaches to compute the mean change was estimated and potential improvements are discussed to enhance policy support. Applying a model ensemble enabled us to obtain highly robust and consistent model results, substantially decreasing uncertainties in the scenario outcome. %0 journal article %@ 0882-8156 %A Pyrina, M., Nonnenmacher, M., Wagner, S., Zorita, E. %D 2021 %J Weather and Forecasting %N 4 %P 1537-1560 %R doi:10.1175/WAF-D-20-0235.1 %T Statistical Seasonal Prediction of European Summer Mean Temperature Using Observational, Reanalysis, and Satellite Data %U https://doi.org/10.1175/WAF-D-20-0235.1 4 %X Furthermore, the predictive potential of SSTs within different areas in the NA basin was tested. The predictive power of SSTs might increase, as in our case, when specific areas are selected. Forecasts based on extratropical SSTs achieve high prediction skill over South Europe. The combined prediction, using SM and SST predictor data, results in r≥0.5 over all European regions south of 50°N and east of 5°W. This is a better skill than the one achieved by other prediction schemes based on dynamical models. Our analysis highlights specific NA mid-latitude regions that are more strongly connected to summer mean European temperature. %0 journal article %@ 2073-4433 %A Pyrina, M., Moreno-Chamarro, E., Wagner, S., Zorita, E. %D 2021 %J Atmosphere %N 5 %P 568 %R doi:10.3390/atmos12050568 %T Surface and Tropospheric Response of North Atlantic Summer Climate from Paleoclimate Simulations of the Past Millennium %U https://doi.org/10.3390/atmos12050568 5 %X We investigate the effects of solar forcing on the North Atlantic (NA) summer climate, in climate simulations with Earth System Models (ESMs), over the preindustrial past millennium (AD 850–1849). We use one simulation and a four-member ensemble performed with the MPI-ESM-P and CESM-LME models, respectively, forced only by low-scaling variations in Total Solar Irradiance (TSI). We apply linear methods (correlation and regression) and composite analysis to estimate the NA surface and tropospheric climatic responses to decadal solar variability. Linear methods in the CESM ensemble indicate a weak summer response in sea-level pressure (SLP) and 500-hPa geopotential height to TSI, with decreased values over Greenland and increased values over the NA subtropics. Composite analysis indicates that, during high-TSI periods, SLP decreases over eastern Canada and the geopotential height at 500-hPa increases over the subtropical NA. The possible summer response of SSTs is overlapped by model internal variability. Therefore, for low-scaling TSI changes, state-of-the-art ESMs disagree on the NA surface climatic effect of solar forcing indicated by proxy-based studies during the preindustrial millennium. The analysis of control simulations indicates that, in all climatic variables studied, spurious patterns of apparent solar response may arise from the analysis of single model simulations. %0 journal article %@ 0273-1177 %A Dinardo, S., Fenoglio-Marc, L., Becker, M., Fernandes, J., Staneva, J., Grayek, S., Benveniste, J. %D 2021 %J Advances in Space Research %N 2 %P 892-929 %R doi:10.1016/j.asr.2020.06.004 %T A RIP-based SAR retracker and its application in North East Atlantic with Sentinel-3 %U https://doi.org/10.1016/j.asr.2020.06.004 2 %X Analyses show that both SAMOSA+ and SAMOSA++ ensure the continuity of the PDGS SAR Marine retracker in the open ocean, leading to clear improvements in the coastal zone, larger for SAMOSA++ than for SAMOSA+. In summary, the new SAMOSA++ retracker retrieves more accurate altimetric parameters in the coastal zone, with a better consistency with respect to regional ocean models and in situ data. %0 journal article %@ 1942-2466 %A Nonnenmacher, M., Greenberg, D. %D 2021 %J Journal of Advances in Modeling Earth Systems %N 7 %P e2021MS002554 %R doi:10.1029/2021MS002554 %T Deep Emulators for Differentiation, Forecasting, and Parametrization in Earth Science Simulators %U https://doi.org/10.1029/2021MS002554 7 %X To understand and predict large, complex and chaotic systems, Earth scientists build simulators from physical laws. Simulators generalize better to new scenarios, require fewer tunable parameters and are more interpretable than non-physical deep learning, but procedures for obtaining their derivatives with respect to their inputs are often unavailable. These missing derivatives limit the application of many important tools for forecasting, model tuning, sensitivity analysis or sub-grid-scale parametrization. Here we propose to overcome this limitation with deep emulator networks that learn to calculate the missing derivatives. By training directly on simulation data without analyzing source code or equations, this approach supports simulators in any programming language on any hardware without specialized routines for each case. To demonstrate the effectiveness of our approach, we train emulators on complete or partial system states of the chaotic Lorenz-96 simulator, and evaluate the accuracy of their dynamics and derivatives as a function of integration time and training dataset size. We further demonstrate that emulator-derived derivatives enable accurate 4D-Var data assimilation and closed-loop training of parametrizations. These results provide a basis for further combining the parsimony and generality of physical models with the power and flexibility of machine learning. %0 journal article %@ 1811-1602 %A Abram, N., Kaufman, D., McGregor, H., Martrat, B., Bothe, O., Linderholm, H. %D 2021 %J Past Global Changes Magazine %N 1 %P 16-17 %R doi:10.22498/pages.29.1.16 %T Global climate goes regional, and vice versa: Reflecting on 14 years of the PAGES 2k Network %U https://doi.org/10.22498/pages.29.1.16 1 %X The past 2000 years of Earth's history provides a critical context for understanding climate variability and change. This is a period where climate changes occurred as a result of well characterized natural climate forcing, as well as unforced internal variability, and has now transitioned into a climate that is strongly forced by human factors. It is also a period where a range of paleoclimate proxy records, often with annual or better resolution, can be used to build up a comprehensive spatial understanding of our climate system. Recent step changes in computing capabilities now allow for ensembles of millennial-length climate-model simulations with which researchers can test and improve our knowledge of the climate system. All of these factors provide a rich scientific backdrop for the work of the PAGES 2k Network. %0 journal article %@ 1811-1602 %A Bothe, O., Rehfeld, K., Konecky, B., Jonkers, L. %D 2021 %J Past Global Changes Magazine %N 1 %P 59 %R doi:10.22498/pages.29.1.59 %T Towards increased interoperability of paleoenvironmental observation data %U https://doi.org/10.22498/pages.29.1.59 1 %X %0 journal article %@ 2662-4435 %A Koul, V., Sguotti, C., Arthun, M., Brune, S., Düsterhus, A., Bogstad, B., Ottersen, G., Baehr, J., Schrum, C. %D 2021 %J Communications Earth & Environment %N 1 %P 140 %R doi:10.1038/s43247-021-00207-6 %T Skilful prediction of cod stocks in the North and Barents Sea a decade in advance %U https://doi.org/10.1038/s43247-021-00207-6 1 %X Reliable information about the future state of the ocean and fish stocks is necessary for informed decision-making by fisheries scientists, managers and the industry. However, decadal regional ocean climate and fish stock predictions have until now had low forecast skill. Here, we provide skilful forecasts of the biomass of cod stocks in the North and Barents Seas a decade in advance. We develop a unified dynamical-statistical prediction system wherein statistical models link future stock biomass to dynamical predictions of sea surface temperature, while also considering different fishing mortalities. Our retrospective forecasts provide estimates of past performance of our models and they suggest differences in the source of prediction skill between the two cod stocks. We forecast the continuation of unfavorable oceanic conditions for the North Sea cod in the coming decade, which would inhibit its recovery at present fishing levels, and a decrease in Northeast Arctic cod stock compared to the recent high levels. %0 journal article %@ 0025-3227 %A Porz, L., Zhang, W., Schrum, C. %D 2021 %J Marine Geology %P 106523 %R doi:10.1016/j.margeo.2021.106523 %T Density-driven bottom currents control development of muddy basins in the southwestern Baltic Sea %U https://doi.org/10.1016/j.margeo.2021.106523 %X The development of two Holocene muddy depocenters in the southwestern Baltic Sea is investigated using sediment budget analysis and numerical modeling. Material derived from the erosion of coastal cliffs surrounding the study area is shown to dominate the supply of fine-grained sediment to the depocenters, while the riverine contribution is an order of magnitude smaller. Comparison with the sink terms, compiled from published geological data, reveals that a substantial additional source of at least 900 kt/yr is required to close the budget, and high-salinity dense inflows from the North Sea carrying suspended sediment are proposed as an additional source mechanism. Seismo-acoustic data show the long-term impact of strong bottom currents, likely linked to dense-water inflows, which produce contouritic deposits in flow-confining channels. We reproduce two distinct inflow events using a coupled hydrodynamic-sediment transport coastal ocean model. The simulations confirm that major inflows are capable of advecting a significant amount of fine-grained sediment into the study area. A scaling relationship based on the simulated fluxes estimates the average amount of sediment imported in this way to the order of 100–900 kt/yr, which is in agreement with the lower limit of the gap in the budget. The amount of sediment advected seems to scale non-linearly with the intensity of the inflow. More field data points are needed in order to improve the accuracy of modeled fluxes and the precision of the scaling relationship. This study shows how the relative contributions of episodic sedimentation events on the longer-term morphology may be quantified. %0 journal article %@ 0308-597X %A Abspoel, A., Mayer, I., Keijser, X., Warmelink, H., Fairgrieve, R., Ripken, M., Abramic, A., Kannen, A., Cormier, R., Kidd, S. %D 2021 %J Marine Policy %P 103486 %R doi:10.1016/j.marpol.2019.02.057 %T Communicating Maritime Spatial Planning: The MSP Challenge approach %U https://doi.org/10.1016/j.marpol.2019.02.057 %X The MSP Challenge uses game technology and role-play to support communication and learning for Marine/Maritime Spatial Planning. Since 2011, a role-playing game, a board game and a digital interactive simulation platform have been developed. The MSP Challenge editions have been used in workshops, conferences, education, as well as for real life stakeholder engagement. The authors give an overview of the development of the MSP Challenge and reflect on the value of the approach as an engaging and ‘fun’ tool for building mutual understanding and communicating MSP. %0 journal article %@ 2296-7745 %A Pein, J., Eisele, A., Sanders, T., Daewel, U., Stanev, E., Beusekom, J., Staneva, J., Schrum, C. %D 2021 %J Frontiers in Marine Science %P 623714 %R doi:10.3389/fmars.2021.623714 %T Seasonal Stratification and Biogeochemical Turnover in the Freshwater Reach of a Partially Mixed Dredged Estuary %U https://doi.org/10.3389/fmars.2021.623714 %X The Elbe estuary is a substantially engineered tidal water body that receives high loads of organic matter from the eutrophied Elbe river. The organic matter entering the estuary at the tidal weir is dominated by diatom populations that collapse in the deepened freshwater reach. Although the estuary’s freshwater reach is considered to manifest vertically homogenous density distribution (i.e., to be well-mixed), several indicators like trapping of particulate organic matter, near-bottom oxygen depletion and ammonium accumulation suggest that the vertical exchange of organic particles and dissolved oxygen is weakened at least temporarily. To better understand the causal links between the hydrodynamics and the oxygen and nutrient cycling in the deepened freshwater reach of the Elbe estuary, we establish a three-dimensional coupled hydrodynamical-biogeochemical model. The model demonstrates good skill in simulating the variability of the physical and biogeochemical parameters in the focal area. Coupled simulations reveal that this region is a hotspot of the degradation of diatoms and organic matter transported from the shallow productive upper estuary and the tidal weir. In summer, the water column weakly stratifies when at the bathymetric jump warmer water from the shallow upper estuary spreads over the colder water of the deepened mid reaches. Enhanced thermal stratification also occurs also in the narrow port basins and channels. Model results show intensification of the particle trapping due to the thermal gradients. The stratification also reduces the oxygenation of the near-bottom region and sedimentary layer inducing oxygen depletion and accumulation of ammonium. The study highlights that the vertical resolution is important for the understanding and simulation of estuarine ecological processes, because even weak stratification impacts the cycling of nutrients via modulation of the vertical mixing of oxygen, particularly in deepened navigation channels and port areas. %0 journal article %@ 2398-9629 %A Bellou, N., Gambardella, C., Karantzalos, K., Monteiro, J.G., Canning-Clode, J., Kemna, S., Arrieta-Giron, C.A., Lemmen, C. %D 2021 %J Nature Sustainability %N 6 %P 516-524 %R doi:10.1038/s41893-021-00726-2 %T Global assessment of innovative solutions to tackle marine litter %U https://doi.org/10.1038/s41893-021-00726-2 6 %X Marine litter is one of the most relevant pollution problems that our oceans are facing today. Marine litter in our oceans is a major threat to a sustainable planet. Here, we provide a comprehensive analysis of cutting-edge solutions developed globally to prevent, monitor and clean marine litter. Prevention in this research includes only innovative solutions to prevent litter entering oceans and seas rather than interventions such as waste reduction and recycling. On the basis of extensive search and data compilation, our analysis reveals that information is dispersed across platforms and is not easily accessible. In total, 177 solutions—the equivalent to <0.9% of the search hits—fulfilled our validation criteria and were evaluated. Most solutions (n = 106, 60%) primarily address monitoring and were developed during the past 3 years, with the scientific community being the key driver. Few solutions reached mature technical readiness and market availability, while none were validated for efficiency and environmental impact. Looking ahead, we elaborate on the limitations of the existing solutions, the challenges of developing new solutions, and provide recommendations for funding schemes and policy instruments to prevent, monitor and clean marine litter globally. In doing so, we encourage researchers, innovators and policy-makers worldwide to act towards achieving and sustaining a cleaner ocean for future generations. %0 journal article %@ 2296-7745 %A Stegert, C., Lenhart, H., Blauw, A., Friedland, R., Leujak, W., Kerimoglu, O. %D 2021 %J Frontiers in Marine Science %P 637483 %R doi:10.3389/fmars.2021.637483 %T Evaluating Uncertainties in Reconstructing the Pre-eutrophic State of the North Sea %U https://doi.org/10.3389/fmars.2021.637483 %X The North Sea is affected by eutrophication problems despite the decreasing riverine nutrient fluxes since the late 1980s. Formally, assessment of the eutrophication state of European marine environments is based on their historical state. Model estimates are increasingly used to support monitoring data that often do not encompass such pre-eutrophic conditions. However, various sources of uncertainties emerge when producing these estimates. In this study, we systematically quantify various sources of uncertainties in terms of variability, and assess their importance for the North Sea. For the reconstruction of the historical state, we use two coupled physical-biogeochemical model systems: ECOHAM on a 20-km grid for the European shelf and GPM on a high-resolution (1.5–4.5 km) grid for the Southern North Sea. To gain insights into the impacts due to the uncertainty in riverine loadings, we consider the historical nutrient inputs from two alternative watershed-models (MONERIS and E-HYPE). Overall, the modeled historic state based on E-HYPE shows higher nutrient concentrations compared to the state based on MONERIS, especially in the coastal regions. Assessing the degree of methodological uncertainties by an inter-comparison of different sources and against natural variabilities provides insight into the reliability of the model-based reconstruction of the historical state. We find that in regions influenced by freshwater from major rivers uncertainties owed to riverine loading scenarios exceed the natural sources of variability. For the offshore regions, natural sources of variability dominate over those caused by model- and scenario-related uncertainties. These findings are expected to assist decision makers and researchers in gaining insight into the degree of confidence in evaluating the model results, and prioritizing the need for refinement of models and scenarios for the production of reliable projections. %0 journal article %@ 2296-7745 %A Jacob, B., Stanev, E. %D 2021 %J Frontiers in Marine Science %P 640214 %R doi:10.3389/fmars.2021.640214 %T Understanding the Impact of Bathymetric Changes in the German Bight on Coastal Hydrodynamics: One Step Toward Realistic Morphodynamic Modeling %U https://doi.org/10.3389/fmars.2021.640214 %X The hydrodynamic response to morphodynamic variability in the coastal areas of the German Bight was analyzed via numerical experiments using time-referenced bathymetric data for the period 1982–2012. Time-slice experiments were conducted for each year with the Semi-implicit Cross-scale Hydroscience Integrated System Model (SCHISM). This unstructured-grid model resolves small-scale bathymetric features in the coastal zone, which are well-resolved in the high-resolution time-referenced bathymetric data (50 m resolution). Their analysis reveals the continuous migration of tidal channels, as well as rather complex change of the depths of tidal flats in different periods. The almost linear relationship between the cross-sectional inlet areas and the tidal prisms of the intertidal basins in the East Frisian Wadden Sea demonstrates that these bathymetric data describe a consistent morphodynamic evolutionary trend. The numerical experiment results are streamlined to explain the hydrodynamic evolution from 1982 to 2012. Although the bathymetric changes were mostly located in a relatively small part of the model area, they resulted in substantial changes in the M2 tidal amplitudes, i.e., larger than 5 cm in some areas. The hydrodynamic response to bathymetric changes largely exceeded the response to sea level rise. The tidal asymmetry estimated from the model appeared very sensitive to bathymetric evolution, particularly between the southern tip of Sylt Island and the Eider Estuary along the eastern coast. The peak current asymmetry weakened from 1982 to 1995 and even reversed within some tidal basins to become flood-dominant. This would suggest that the flushing trend in the 1980s was reduced or reversed in the second half of the studied period. Salinity also appeared sensitive to bathymetric changes; the deviations in the individual years reached ~22 psu in the tidal channels and tidal flats. One practical conclusion from the present numerical simulations is that wherever possible, the numerical modeling of near-coastal zones must employ time-referenced bathymetry data. The second, perhaps even more important conclusion, is that the progress of morphodynamic modeling in realistic ocean settings with multiple scales and varying bottom forms is strongly dependent on the availability of bathymetric data with appropriate temporal and spatial resolution. %0 journal article %@ 2045-2322 %A Akhtar, N., Geyer, B., Rockel, B., Sommer, P., Schrum, C. %D 2021 %J Scientific Reports %N 1 %P 11826 %R doi:10.1038/s41598-021-91283-3 %T Accelerating deployment of offshore wind energy alter wind climate and reduce future power generation potentials %U https://doi.org/10.1038/s41598-021-91283-3 1 %X The European Union has set ambitious CO2 reduction targets, stimulating renewable energy production and accelerating deployment of offshore wind energy in northern European waters, mainly the North Sea. With increasing size and clustering, offshore wind farms (OWFs) wake effects, which alter wind conditions and decrease the power generation efficiency of wind farms downwind become more important. We use a high-resolution regional climate model with implemented wind farm parameterizations to explore offshore wind energy production limits in the North Sea. We simulate near future wind farm scenarios considering existing and planned OWFs in the North Sea and assess power generation losses and wind variations due to wind farm wake. The annual mean wind speed deficit within a wind farm can reach 2–2.5 ms−1 depending on the wind farm geometry. The mean deficit, which decreases with distance, can extend 35–40 km downwind during prevailing southwesterly winds. Wind speed deficits are highest during spring (mainly March–April) and lowest during November–December. The large-size of wind farms and their proximity affect not only the performance of its downwind turbines but also that of neighboring downwind farms, reducing the capacity factor by 20% or more, which increases energy production costs and economic losses. We conclude that wind energy can be a limited resource in the North Sea. The limits and potentials for optimization need to be considered in climate mitigation strategies and cross-national optimization of offshore energy production plans are inevitable. %0 journal article %@ 0452-7739 %A Yi, X., Weisse, R. %D 2021 %J Die Küste %N 89 %P 173-191 %R doi:10.18171/1.089107 %T Modellgestütze Untersuchungen zum Einfluss großräumiger Faktoren auf die Tidedynamik in der Deutschen Bucht %U https://doi.org/10.18171/1.089107 89 %X Increases in mean tidal range are observed at most tide gauges along the German North Sea coast. This increase is most pronounced since about the 1950s and is superimposed with strong inter-annual and decadal variability. Amplitudes and characteristics of the increases vary among tide gauges but generally, a large-scale increase in mean tidal high water relevant for design of coastal protection is observed. There are a number of local, regional and large-scale processes that, together with their interactions, may potentially account for the observed changes. The objective of this study is to assess potential contributions from regional and large-scale factors using a combination of modelling and statistical approaches and techniques. No process was identified that could solely account for most of the observed changes. Instead, an interplay between large-scale, regional as well as local factors and their interactions appears to be the most likely explanation for the observed changes. %0 journal article %@ 2073-4441 %A Staneva, J., Ricker, M., Alvarez, R., Breivik, Ø., Schrum, C. %D 2021 %J Water %N 4 %P 415 %R doi:10.3390/w13040415 %T Effects of Wave-Induced Processes in a Coupled Wave–Ocean Model on Particle Transport Simulations %U https://doi.org/10.3390/w13040415 4 %X This study investigates the effects of wind–wave processes in a coupled wave–ocean circulation model on Lagrangian transport simulations. Drifters deployed in the southern North Sea from May to June 2015 are used. The Eulerian currents are obtained by simulation from the coupled circulation model (NEMO) and the wave model (WAM), as well as a stand-alone NEMO circulation model. The wave–current interaction processes are the momentum and energy sea state dependent fluxes, wave-induced mixing and Stokes–Coriolis forcing. The Lagrangian transport model sensitivity to these wave-induced processes in NEMO is quantified using a particle drift model. Wind waves act as a reservoir for energy and momentum. In the coupled wave–ocean circulation model, the momentum that is transferred into the ocean model is considered as a fraction of the total flux that goes directly to the currents plus the momentum lost from wave dissipation. Additional sensitivity studies are performed to assess the potential contribution of windage on the Lagrangian model performance. Wave-induced drift is found to significantly affect the particle transport in the upper ocean. The skill of particle transport simulations depends on wave–ocean circulation interaction processes. The model simulations were assessed using drifter and high-frequency (HF) radar observations. The analysis of the model reveals that Eulerian currents produced by introducing wave-induced parameterization into the ocean model are essential for improving particle transport simulations. The results show that coupled wave–circulation models may improve transport simulations of marine litter, oil spills, larval drift or transport of biological materials. %0 journal article %@ 0280-6495 %A Petrik, R., Geyer, B., Rockel, B. %D 2021 %J Tellus A %N 1 %P 1-28 %R doi:10.1080/16000870.2020.1804294 %T On the diurnal cycle and variability of winds in the lower planetary boundary layer: evaluation of regional reanalyses and hindcasts %U https://doi.org/10.1080/16000870.2020.1804294 1 %X To accurately calculate the impact of renewables on power production in complex electric power grids, high-resolution and ideally seamless data within the planetary boundary layer are required. Therefore, the quality of different regional reanalyses and hindcasts is evaluated with respect to the representation of the planetery boundary layer and related sub-daily processes. On the one hand, high resolution regional reanalysis from the UERRA (UE-SMHI, UE-UKMO) and a similar project (COSMO-REA6) are considered. On the other hand, two hindcasts based on the COSMO-REA6 configuration are included in this study, i.e. a simulation with perfect boundaries and a simulation additionally utilizing spectral nudging. The focus of the evaluation is on measurements at four flux towers that are not part of any assimilation procedure. In this paper, we will show that the model’s quality depends on both the complete model system – assimilation method, resolution and physical parameterization – as well as on the performance measure. The daily cycle is best depicted by the hindcasts and even COSMO-REA6 hardly introduces spurious variability. UE-SMHI (3D-Var) suffers from spin-up in particular visible at the elevated levels, whereas the spin-up is damped in UE-UKMO (4D-Var). Investigation of atmospheric stability reveals that diurnal variation of stratification is for the most part well reproduced, but strong deficits were found for all COSMO simulations in reproducing strong stratification and corresponding wind speed gradients. Moreover, an overestimation of superadiabatic lapse rates and corresponding overly weak turbulent mixing is found for UE-UKMO. Furthermore, a combination of ramp statistics and contingency tables is utilized to detect a clear advantage of sophisticated assimilation systems over hindcasts. The evaluation framework presented underpins the importance of ramp statistics and vertical measurement profiles, especially with respect to assessing long-term simulations. %0 journal article %@ 0273-1177 %A Abdalla, S., Abdeh Kolahchi, A., Adusumilli, S., Stanev, E., Staneva, J. %D 2021 %J Advances in Space Research %N 2 %P 319-363 %R doi:10.1016/j.asr.2021.01.022 %T Altimetry for the future: Building on 25 years of progress %U https://doi.org/10.1016/j.asr.2021.01.022 2 %X In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. %0 journal article %@ 1616-7341 %A Logemann, K., Linardakis, L., Korn, P., Schrum, C. %D 2021 %J Ocean Dynamics %P 43-57 %R doi:10.1007/s10236-020-01428-7 %T Global tide simulations with ICON-O: testing the model performance on highly irregular meshes %U https://doi.org/10.1007/s10236-020-01428-7 %X The global tide is simulated with the global ocean general circulation model ICON-O using a newly developed tidal module, which computes the full tidal potential. The simulated coastal M2 amplitudes, derived by a discrete Fourier transformation of the output sea level time series, are compared with the according values derived from satellite altimetry (TPXO-8 atlas). The experiments are repeated with four uniform and sixteen irregular triangular grids. The results show that the quality of the coastal tide simulation depends primarily on the coastal resolution and that the ocean interior can be resolved up to twenty times lower without causing considerable reductions in quality. The mesh transition zones between areas of different resolutions are formed by cell bisection and subsequent local spring optimisation tolerating a triangular cell’s maximum angle up to 84°. Numerical problems with these high-grade non-equiangular cells were not encountered. The results emphasise the numerical feasibility and potential efficiency of highly irregular computational meshes used by ICON-O. %0 journal article %@ 1461-0248 %A Ryabov, A., Kerimoglu, O., Litchman, E., Olenina, I., Roselli, L., Basset, A., Stanca, E., Blasius, B. %D 2021 %J Ecology Letters %N 4 %P 847-861 %R doi:10.1111/ele.13680 %T Shape matters: the relationship between cell geometry and diversity in phytoplankton %U https://doi.org/10.1111/ele.13680 4 %X Size and shape profoundly influence an organism’s ecophysiological performance and evolutionary fitness, suggesting a link between morphology and diversity. However, not much is known about how body shape is related to taxonomic richness, especially in microbes. Here we analyse global datasets of unicellular marine phytoplankton, a major group of primary producers with an exceptional diversity of cell sizes and shapes and, additionally, heterotrophic protists. Using two measures of cell shape elongation, we quantify taxonomic diversity as a function of cell size and shape. We find that cells of intermediate volume have the greatest shape variation, from oblate to extremely elongated forms, while small and large cells are mostly compact (e.g. spherical or cubic). Taxonomic diversity is strongly related to cell elongation and cell volume, together explaining up to 92% of total variance. Taxonomic diversity decays exponentially with cell elongation and displays a log-normal dependence on cell volume, peaking for intermediate-volume cells with compact shapes. These previously unreported broad patterns in phytoplankton diversity reveal selective pressures and ecophysiological constraints on the geometry of phytoplankton cells which may improve our understanding of marine ecology and the evolutionary rules of life. %0 journal article %@ 0003-0007 %A Menard, C., Essery, R., Krinner, G., Arduini, G., Bartlett, P., Boone, A., Brutel-vuilmet, C., Burke, E., Cuntz, M., Dai, Y., Decharme, B., Dutra, E., Fang, X., Fierz, C., Gusev, Y., Hagemann, S., Haverd, V., Kim, H., Lafaysse, M., Marke, T., Nasonova, O., Nitta, T., Niwano, M., Pomeroy, J., Schädler, G., Semenov, V., Smirnova, T., Strasser,U., Swenson, S., Turkov, D., Wever, N., Yuan, H. %D 2021 %J Bulletin of the American Meteorological Society %N 1 %P E61-E79 %R doi:10.1175/BAMS-D-19-0329.1 %T Scientific and Human Errors in a Snow Model Intercomparison %U https://doi.org/10.1175/BAMS-D-19-0329.1 1 %X Twenty-seven models participated in the Earth System Model - Snow Model Intercomparison Project (ESM-SnowMIP), the most data-rich MIP dedicated to snow modelling. Our findings do not support the hypothesis advanced by previous snow MIPs: evaluating models against more variables, and providing evaluation datasets extended temporally and spatially does not facilitate identification of key new processes requiring improvement to model snow mass and energy budgets, even at point scales. In fact, the same modelling issues identified by previous snow MIPs arose: albedo is a major source of uncertainty, surface exchange parametrizations are problematic and individual model performance is inconsistent. This lack of progress is attributed partly to the large number of human errors that led to anomalous model behaviour and to numerous resubmissions. It is unclear how widespread such errors are in our field and others; dedicated time and resources will be needed to tackle this issue to prevent highly sophisticated models and their research outputs from being vulnerable because of avoidable human mistakes. The design of and the data available to successive snow MIPs were also questioned. Evaluation of models against bulk snow properties was found to be sufficient for some but inappropriate for more complex snow models whose skills at simulating internal snow properties remained untested. Discussions between the authors of this paper on the purpose of MIPs revealed varied, and sometimes contradictory, motivations behind their participation. These findings started a collaborative effort to adapt future snow MIPs to respond to the diverse needs of the community. %0 journal article %@ 0930-7575 %A Evans, J., Di Virgilio, G., Hirsch, A., Hoffmann, P., Remedio, A., Ji, F., Rockel, B., Coppola, E. %D 2021 %J Climate Dynamics %N 5-6 %P 1385-1401 %R doi:10.1007/s00382-020-05459-0 %T The CORDEX-Australasia ensemble: evaluation and future projections %U https://doi.org/10.1007/s00382-020-05459-0 5-6 %X A new regional climate projection ensemble has been created for the Australasia region as part of the World Climate Research Programs Coordinated Regional Downscaling Experiment (CORDEX). The CORDEX-Australasia ensemble is the largest regional climate projection ensemble ever created for the region. It is a 20-member ensemble made by 6 regional climate models downscaling 11 global climate models. Overall the ensemble produces a good representation of recent climate. Consistent biases within the ensemble include an underestimation of the diurnal temperature range and an underestimation of precipitation across much of southern Australia. Under a high emissions scenario projected temperature changes by the end of the twenty-first century reach ~ 5 K in the interior of Australia with smaller increases found toward the coast. Projected precipitation changes are towards drying, particularly in the most populated areas of the southwest and southeast of the continent. The projected precipitation change is very seasonal with summer projected to see little change leaning toward an increase. These results provide a foundation enabling future studies of regional climate changes, climate change impacts, and adaptation options for Australia. %0 journal article %@ 0196-2892 %A Bärfuss, K., Djath, B., Lampert, A., Schulz-Stellenfleth, J. %D 2021 %J IEEE Transactions on Geoscience and Remote Sensing %N 6 %P 4608-4617 %R doi:10.1109/TGRS.2020.3017861 %T Airborne LiDAR Measurements of Sea Surface Properties in the German Bight %U https://doi.org/10.1109/TGRS.2020.3017861 6 %X Sea surface measurements are mainly gathered using satellite altimeter, buoy, and platform measurements. Satellite measurements typically have a coarse spatial resolution and need recalibration in coastal regions, whereas point measurements of buoys only represent limited areas around the measurement point because of the complex coastal bathymetry. Wave models (WAM) are used to expand the sparse observations in space and time. As a part of the project WIndPArk far-field (WIPAFF), which focused on wakes behind offshore wind farms, extensive airborne light detection and ranging (LiDAR) measurements of ocean waves in the German Bight were performed for more than 90 h. The LiDAR data processed for significant wave height can be used to validate and improve WAM models for complex areas and fill the observation gap between satellite altimeter and point measurements. This creates a detailed picture of the sea surface for coastal engineering and environmental applications. After introducing the measurement techniques and the data situation, intercomparisons between the available airborne measurements, buoy data, and WAM model output are presented to provide an insight into the potential of airborne LiDAR measurements for wave characterization and wave model validation. %0 journal article %@ 0899-8418 %A Krieger, D., Krueger, O., Feser, F., Weisse, R., Tinz, B., von Storch, H. %D 2021 %J International Journal of Climatology %N S1 %P E2159-E2177 %R doi:10.1002/joc.6837 %T German Bight storm activity; 1897-2018 %U https://doi.org/10.1002/joc.6837 S1 %X This study investigates the evolution of German Bight (southeastern North Sea) storminess from 1897 to 2018 through analysing upper quantiles of geostrophic wind speeds, which act as a proxy for past storm activity. Here, geostrophic wind speeds are calculated from triplets of mean sea level pressure observations that form triangles over the German Bight. The data used in the manuscript are provided by the International Surface Pressure Databank and the national meteorological services of Denmark, Germany, and the Netherlands. The derivation of storm activity is achieved by enhancing the established triangle proxy method via combining and merging storminess time series from numerous partially overlapping triangles in an ensemble‐like manner. The utilized approach allows for the construction of robust, long‐term and subdaily German Bight storminess time series. Further, the method provides insights into the underlying uncertainty of the time series. The results show that storm activity over the German Bight is subject to multidecadal variability. The latest decades are characterized by an increase in activity from the 1960s to the 1990s, followed by a decline lasting into the 2000s and below‐average activity up until present. The results are backed through a comparison with reanalysis products from four datasets, which provide high‐resolution wind and pressure data starting in 1979 and offshore wind speed measurements taken from the FINO‐WIND project. This study also finds that German Bight storminess positively correlates with storminess in the NE Atlantic in general. In certain years, however, notably different levels of storm activity in the two regions can be found, which likely result from shifted large‐scale circulation patterns. %0 journal article %@ 0273-1177 %A Fenoglio, L., Dinardo, S., Uebbing, B., Buchhaupt, C., Gärtner, M., Staneva, J., Becker, M., Klos, A., Kusche, J. %D 2021 %J Advances in Space Research %N 2 %P 571-592 %R doi:10.1016/j.asr.2020.10.041 %T Advances in NE-Atlantic coastal sea level change monitoring by Delay Doppler altimetry %U https://doi.org/10.1016/j.asr.2020.10.041 2 %X The larger departure between monthly tide gauge and LRM altimetric time-series as between tide gauge and SAR altimetric time-series confirms the higher accuracy of SAR data compared to LRM. Finally, the sea level trends of the merged LRM and SAR altimetry time-series are consistent with the LRM trends. %0 journal article %@ 1561-8633 %A van Garderen, L., Feser, F., Shepherd, T. %D 2021 %J Natural Hazards and Earth System Sciences %N 1 %P 171-186 %R doi:10.5194/nhess-21-171-2021 %T A methodology for attributing the role of climate change in extreme events: a global spectrally nudged storyline %U https://doi.org/10.5194/nhess-21-171-2021 1 %X Extreme weather events are generally associated with unusual dynamical conditions, yet the signal-to-noise ratio of the dynamical aspects of climate change that are relevant to extremes appears to be small, and the nature of the change can be highly uncertain. On the other hand, the thermodynamic aspects of climate change are already largely apparent from observations and are far more certain since they are anchored in agreed-upon physical understanding. The storyline method of extreme-event attribution, which has been gaining traction in recent years, quantitatively estimates the magnitude of thermodynamic aspects of climate change, given the dynamical conditions. There are different ways of imposing the dynamical conditions. Here we present and evaluate a method where the dynamical conditions are enforced through global spectral nudging towards reanalysis data of the large-scale vorticity and divergence in the free atmosphere, leaving the lower atmosphere free to respond. We simulate the historical extreme weather event twice: first in the world as we know it, with the events occurring on a background of a changing climate, and second in a “counterfactual” world, where the background is held fixed over the past century. We describe the methodology in detail and present results for the European 2003 heatwave and the Russian 2010 heatwave as a proof of concept. These show that the conditional attribution can be performed with a high signal-to-noise ratio on daily timescales and at local spatial scales. Our methodology is thus potentially highly useful for realistic stress testing of resilience strategies for climate impacts when coupled to an impact model. %0 journal article %@ 0094-8276 %A Stanev, E., Chtirkova, B., Peneva, E. %D 2021 %J Geophysical Research Letters %N 2 %P 2020GL091788 %R doi:10.1029/2020GL091788 %T Geothermal Convection and Double Diffusion Based on Profiling Floats in the Black Sea %U https://doi.org/10.1029/2020GL091788 2 %X Here, we revisit the existing concepts of the vertical structure of deep layers in the Black Sea using data from sensors deployed on profiling floats. The deep transition layer (DTL) between 700 and 1700 m acts as an interface between the baroclinic layer and the largest bottom convective layer (BCL) of the world oceans. On top of DTL are the warm intermediate layer (WIL) and deep cold intermediate layer (DCIL). They both showed strong trends in the last fifteen years due to warmer climate and intensification of warmer intrusions from Bosporus. A “salinity wave” was detected in 2005‐2009 below ∼1700 m, which evidenced for the first time the penetration of gravity flow from Bosporus down to the bottom. The layering of water masses was explained as resulting from the different distribution of sources of heat and salt, double duffusion and balances between the geothermal and salinity flows in the BCL. %0 journal article %@ 0034-4257 %A Peng, J., Albergel, C., Balenzano, A., Brocca, L., Cartus, O., Cosh, M.H., Crow, W.T., Dabrowska-Zielinska, K., Dadson, S., Davidson, M.W.J., de Rosnay, P., Dorigo, W., Gruber, A., Hagemann, S., Hirschi, M., Kerr, Y.H., Lovergine, F., Mahecha, M.D., Marzahn, P., Mattia, F., Musial, J.P., Preuschmann, S., Reichle, R.H., Satalino, G., Silgram, M., van Bodegom, P.M., Verhoest, N.E.C., Wagner, W., Walker, J.P., Wegmüller, U., Loew, A. %D 2021 %J Remote Sensing of Environment %P 112162 %R doi:10.1016/j.rse.2020.112162 %T A roadmap for high-resolution satellite soil moisture applications – confronting product characteristics with user requirements %U https://doi.org/10.1016/j.rse.2020.112162 %X Soil moisture observations are of broad scientific interest and practical value for a wide range of applications. The scientific community has made significant progress in estimating soil moisture from satellite-based Earth observation data, particularly in operationalizing coarse-resolution (25-50 km) soil moisture products. This review summarizes existing applications of satellite-derived soil moisture products and identifies gaps between the characteristics of currently available soil moisture products and the application requirements from various disciplines. We discuss the efforts devoted to the generation of high-resolution soil moisture products from satellite Synthetic Aperture Radar (SAR) data such as Sentinel-1 C-band backscatter observations and/or through downscaling of existing coarse-resolution microwave soil moisture products. Open issues and future opportunities of satellite-derived soil moisture are discussed, providing guidance for further development of operational soil moisture products and bridging the gap between the soil moisture user and supplier communities. %0 journal article %@ 2169-9275 %A Stanev, E., Chtirkova, B. %D 2021 %J Journal of Geophysical Research : Oceans %N 2 %P e2020JC016429 %R doi:10.1029/2020JC016429 %T Interannual change in mode waters: Case of the Black Sea %U https://doi.org/10.1029/2020JC016429 2 %X More than 6000 profiles from profiling floats in the Black Sea over the 2005‐2020 period were used to study the ventilation of this basin and the mixing pathways along isopycnals. The layer of the minimum potential vorticity (PV), the Black Sea pycnostad, approximately follows the core of the cold intermediate layer (CIL), similar to the case of oceanic mode waters. However, unlike in the ocean, the horizontal patterns of PV are shaped by cyclonic gyre circulation. There is a principle difference in the probability distribution of the thermohaline properties presented in geopotential coordinates from those presented in density coordinates. In the latter case, several mixing pathways, which are not known from previous studies, dominate the ocean states. These formed after three intermittent events of cold water formation. The density ratio decreased three times during the last 15 years, revealing the decreasing role of temperature in the vertical layering of the Black Sea halocline. The basin‐wide distribution of PV above σθ = 16, which is where the maximum vertical density gradient appears, is opposite to the distribution below this depth. This finding suggests a complex change in the mesoscale dynamics in different layers. Comparisons of observations with data from the Copernicus Black Sea operational model demonstrate that the mixing parameterizations of models need further improvements. %0 journal article %@ 0894-8755 %A Feser, F., Krueger, O., Woth, K., van Garderen, L. %D 2021 %J Journal of Climate %N 7 %P 2411-2428 %R doi:10.1175/JCLI-D-20-0529.1 %T North Atlantic Winter Storm Activity in Modern Reanalyses and Pressure-Based Observations %U https://doi.org/10.1175/JCLI-D-20-0529.1 7 %X The similarity of the geostrophic wind speed storm index to reanalyzed high wind speed percentiles and storm numbers confirms its suitability to describe storm frequencies and intensities for multi-decadal time scales. The results show that high wind speeds, storm numbers, and spatial storm track distributions are generally alike in high-resolution reanalyses and downscaled data sets and they reveal an increasing similarity to observations over time. Strong decadal and multi-decadal variability emerged in high wind speed percentiles and storm frequency, but no long-term changes for the last decades were detected. %0 journal article %@ 2296-7745 %A Sanchez-Arcilla, A., Staneva, J., Cavaleri, L., Badger, M., Bidlot, J., Sorensen, J., Hansen, L., Martin, A., Saulter, A., Espino, M., Miglietta, M., Mestres, M., Bonaldo, D., Pezzutto, P., Schulz-Stellenfleth, J., Wiese, A., Larsen, X., Carniel, S., Bolaños, R., Abdalla, S., Tiesi, A. %D 2021 %J Frontiers in Marine Science %P 604741 %R doi:10.3389/fmars.2021.604741 %T CMEMS-Based Coastal Analyses: Conditioning, Coupling and Limits for Applications %U https://doi.org/10.3389/fmars.2021.604741 %X Recent advances in numerical modeling, satellite data, and coastal processes, together with the rapid evolution of CMEMS products and the increasing pressures on coastal zones, suggest the timeliness of extending such products toward the coast. The CEASELESS EU H2020 project combines Sentinel and in-situ data with high-resolution models to predict coastal hydrodynamics at a variety of scales, according to stakeholder requirements. These predictions explicitly introduce land discharges into coastal oceanography, addressing local conditioning, assimilation memory and anisotropic error metrics taking into account the limited size of coastal domains. This article presents and discusses the advances achieved by CEASELESS in exploring the performance of coastal models, considering model resolution and domain scales, and assessing error generation and propagation. The project has also evaluated how underlying model uncertainties can be treated to comply with stakeholder requirements for a variety of applications, from storm-induced risks to aquaculture, from renewable energy to water quality. This has led to the refinement of a set of demonstrative applications, supported by a software environment able to provide met-ocean data on demand. The article ends with some remarks on the scientific, technical and application limits for CMEMS-based coastal products and how these products may be used to drive the extension of CMEMS toward the coast, promoting a wider uptake of CMEMS-based predictions. %0 journal article %@ 1758-678X %A Zhou, S., William, A., Lintner, B., Berg, A., Zhang, Y., Keenan, T., Cook, B., Hagemann, S., Seneviratne, S., Gentine, P. %D 2021 %J Nature Climate Change %P 38-44 %R doi:10.1038/s41558-020-00945-z %T Soil moisture–atmosphere feedbacks mitigate declining water availability in drylands %U https://doi.org/10.1038/s41558-020-00945-z %X Global warming alters surface water availability (precipitation minus evapotranspiration, P–E) and hence freshwater resources. However, the influence of land–atmosphere feedbacks on future P–E changes and the underlying mechanisms remain unclear. Here we demonstrate that soil moisture (SM) strongly impacts future P–E changes, especially in drylands, by regulating evapotranspiration and atmospheric moisture inflow. Using modelling and empirical approaches, we find a consistent negative SM feedback on P–E, which may offset ~60% of the decline in dryland P–E otherwise expected in the absence of SM feedbacks. The negative feedback is not caused by atmospheric thermodynamic responses to declining SM; rather, reduced SM, in addition to limiting evapotranspiration, regulates atmospheric circulation and vertical ascent to enhance moisture transport into drylands. This SM effect is a large source of uncertainty in projected dryland P–E changes, underscoring the need to better constrain future SM changes and improve the representation of SM–atmosphere processes in models. %0 journal article %@ 0025-3227 %A Porz, L., Zhang, W., Hanebuth, T., Schrum, C. %D 2021 %J Marine Geology %P 106402 %R doi:10.1016/j.margeo.2020.106402 %T Physical processes controlling mud depocenter development on continental shelves – Geological, oceanographic, and modeling concepts %U https://doi.org/10.1016/j.margeo.2020.106402 %X The ability of numerical models to accurately predict medium to long-term mud accumulation is restricted not only by computational costs, but also by insufficient parametrizations of the muddy sedimentation process. These remain challenging to constrain due to the multiplicity and complexity of factors affecting the cohesive properties of mud, including its state of consolidation, and the amount and type of organic matter present. Bridging the gap between individual events and long-term accumulation is the key to a more complete understanding of sedimentation processes in MDCs. %0 journal article %@ 0141-1136 %A Weinert, M., Mathis, M., Kröncke, I., Pohlmann, T., Reiss, H. %D 2021 %J Marine Environmental Research %P 105230 %R doi:10.1016/j.marenvres.2020.105230 %T Climate change effects on marine protected areas: Projected decline of benthic species in the North Sea %U https://doi.org/10.1016/j.marenvres.2020.105230 %X Climate change is a global threat for marine ecosystems, their biodiversity and consequently ecosystem services. In the marine realm, marine protected areas (MPAs) were designated to counteract regional pressures, but they might be ineffective to protect vulnerable species and habitats, if their distribution is affected by global climate change. We used six Species Distribution Models (GLM, MARS, FDA, RF, GBM, MAXENT) to project changes in the distribution of eight benthic indicator and key species under climate change in the North Sea MPAs for 2050 and 2099. The projected distribution area of most species will be stable or even increase within the MPAs between 2001 and 2050. Thereafter, the distribution area decreased, especially within MPAs in the central North Sea by 2099, and some key species even disappeared from the MPAs. Consequently, the monitoring and protection of benthic species might not be possible within static MPA borders under climate change. %0 journal article %@ 2662-4435 %A Geyer, B., Ludwig, T., von Storch, H. %D 2021 %J Communications Earth & Environment %N 1 %P 17 %R doi:10.1038/s43247-020-00085-4 %T Limits of reproducibility and hydrodynamic noise in atmospheric regional modelling %U https://doi.org/10.1038/s43247-020-00085-4 1 %X Reproducibility of research results is a fundamental quality criterion in science; thus, computer architecture effects on simulation results must be determined. Here, we investigate whether an ensemble of runs of a regional climate model with the same code on different computer platforms generates the same sequences of similar and dissimilar weather streams when noise is seeded using different initial states of the atmosphere. Both ensembles were produced using a regional climate model named COSMO-CLM5.0 model with ERA-Interim forcing. Divergent phase timing was dependent on the dynamic state of the atmosphere and was not affected by noise seeded by changing computers or initial model state variations. Bitwise reproducibility of numerical results is possible with such models only if everything is fixed (i.e., computer, compiler, chosen options, boundary values, and initial conditions) and the order of mathematical operations is unchanged between program runs; otherwise, at best, statistically identical simulation results can be expected. %0 journal article %@ 0264-8172 %A Chen, H., Stow, D., Xie, X., Ren, J., Mao, K., Gao, Y., Chen, B., Zhang, W., Vandorpe, T., Van Rooij, D. %D 2021 %J Marine and Petroleum Geology %P 104803 %R doi:10.1016/j.marpetgeo.2020.104803 %T Depositional architecture and evolution of basin-floor fan systems since the Late Miocene in the Northwest Sub-Basin, South China Sea %U https://doi.org/10.1016/j.marpetgeo.2020.104803 %X The sediment budget of the Northwest Sub-basin, South China Sea since the Late Miocene (11.6 Ma, average thickness > 1000 m) accounts for more than two-thirds of the total infill since the initial ocean spreading of the sub-basin (32 Ma). The sediment sources and architectural pattern of these deposits, however, are poorly known. Using high-resolution 2D reflection seismic data with age constraint from IODP boreholes, we have documented two interdigitating basin-floor fan systems that developed since the Late Miocene. These were fed by two of the largest deep-water canyon systems worldwide, from the west (the Central Canyon/Xisha Trough) and the northeast (the Pearl River Canyon), as well as from smaller headless canyons and gullies across the surrounding slopes. Based on careful analysis of seismic facies, their geometry and occurrence, we identify the principal deep-water architectural elements, including the multi-scale channels, channel-levee complexes, lobes, sheets and drapes, mass-transport deposits, volcanic intrusions, turbidity-current sediment-wave fields, and a contourite drift/terrace. %0 journal article %@ 1758-678X %A Pokhrel, Y., Felfelani, F., Satoh, Y., Boulange, J., Burek, P., Gädeke, A., Gerten, D., Gosling, S.N., Grillakis, M., Gudmundsson, L., Hanasaki, N., Kim, H., Koutroulis, A., Liu, J., Papadimitriou, L., Schewe, J., Müller Schmied, H., Stacke, T., Telteu, C.-E., Thiery, W., Veldkamp, T., Zhao, F., Wada, Y. %D 2021 %J Nature Climate Change %N 3 %P 226-233 %R doi:10.1038/s41558-020-00972-w %T Global terrestrial water storage and drought severity under climate change %U https://doi.org/10.1038/s41558-020-00972-w 3 %X Terrestrial water storage (TWS) modulates the hydrological cycle and is a key determinant of water availability and an indicator of drought. While historical TWS variations have been increasingly studied, future changes in TWS and the linkages to droughts remain unexamined. Here, using ensemble hydrological simulations, we show that climate change could reduce TWS in many regions, especially those in the Southern Hemisphere. Strong inter-ensemble agreement indicates high confidence in the projected changes that are driven primarily by climate forcing rather than land and water management activities. Declines in TWS translate to increases in future droughts. By the late twenty-first century, the global land area and population in extreme-to-exceptional TWS drought could more than double, each increasing from 3% during 1976–2005 to 7% and 8%, respectively. Our findings highlight the importance of climate change mitigation to avoid adverse TWS impacts and increased droughts, and the need for improved water resource management and adaptation. %0 journal article %@ 0029-8018 %A Benetazzo, A., Barbariol, F., Pezzutto, P., Staneva, J., Behrens, A., Davison, S., Bergamasco, F., Sclavo, M., Cavaleri, L. %D 2021 %J Ocean Engineering %P 108263 %R doi:10.1016/j.oceaneng.2020.108263 %T Towards a unified framework for extreme sea waves from spectral models: rationale and applications %U https://doi.org/10.1016/j.oceaneng.2020.108263 %X Reliable predictions of oceanic waves during storms have always been foremost for offshore design and operation, coastal hazards, and navigation safety. Indeed, many accidents that occurred during storms were ascribed to the impact with unforeseen large waves. In this context, the purpose of this study is to improve the present state extreme wave estimate from spectral wave models. We describe an implementation for the WAM model, and we investigate the use of WAM and WAVEWATCH III fed with common routines designed to evaluate the short-term/range maximum wave statistics. An extensive assessment of models' results in the Adriatic and North Sea is performed using time and space-time wave measurements, and through an intercomparison between WAM and WAVEWATCH III applied with three different input/dissipation source term parametrizations (ST3/4/6). Further, models’ capabilities are investigated, and extreme waves characterized, in the Mediterranean Sea, aiming also at disentangling the wave spectrum bulk parameters that may point to favorable conditions for the generation of high waves. Based on the comparisons between model results and measurements, we conclude that for the model characterization of extremes, the accuracy of the significant wave height is pivotal; differences between models of other spectral parameters seem to have a minor effect. %0 journal article %@ 0022-1694 %A Zhang, Y., Ren, J., Zhang, W., Wu, J. %D 2021 %J Journal of Hydrology %P 126063 %R doi:10.1016/j.jhydrol.2021.126063 %T Importance of salinity-induced stratification on flocculation in tidal estuaries %U https://doi.org/10.1016/j.jhydrol.2021.126063 %X Flocculation of suspended particles in tidal estuaries exhibits large spatiotemporal variability due to an interplay of various physical and biogeochemical drivers. Salinity (S) is known to promote flocculation of fine-grained suspended particulate matter (SPM). However, the influence of salinity and salinity-induced stratification on flocculation has not been sufficiently investigated yet. This study aims to understand how these two factors, interactively with turbulent shear (G) and SPM concentration (C), control the vertical variation of floc size and flocculation process in different depth layers in a typical tide-dominated estuarine environment. Analysis of field observation data shows that flocculi (diameter < 20 μm) are mainly affected by C and originate primarily from local resuspension. Macroflocs (> 200 μm) are mainly controlled by stratification that greatly improves aggregate collision efficiency; Microflocs (20-200 μm), as a transition group between flocculi and macroflocs, are affected by dynamics of both sides. They are influenced jointly by C, G and stratification. Besides, the fresh water-dominated surface layer is dominated by small particles (flocculi and microflocs), confined in a relatively narrow particle size range between Ο (100) and Ο (101) as a result of the low level of both C (13-20 mg/L) and S (< 2 practical salinity units). Below the surface layer, floc size increases drastically along with an increased salinity-induced density gradient and achieves maximum particle size (Ο (102)) within the stratified layer. Because of its high efficiency in promoting flocculation and formation of macroflocs, the stratified layer around the halocline can be regarded as an optimal flocculation zone. The benthic layer is characterized by high C (> 30 mg/L), gentle G (∼5/s), and periodic stratification, which result in a wide size range between Ο (101) and Ο (102) with microflocs as the dominant group. Finally, we found that the accuracy of flocculation modeling can be significantly improved by integrating a simple relationship between particle collision and stratification. %0 journal article %@ 1991-959X %A Van Pham, T., Steger, C., Rockel, B., Keuler, K., Kirchner, I., Mertens, M., Rieger, D., Zängl, G., Früh, B. %D 2021 %J Geoscientific Model Development %N 2 %P 985-1005 %R doi:10.5194/gmd-14-985-2021 %T ICON in Climate Limited-area Mode (ICON release version 2.6.1): a new regional climate model %U https://doi.org/10.5194/gmd-14-985-2021 2 %X For the first time, the Limited-Area Mode of the new ICON (Icosahedral Nonhydrostatic) weather and climate model has been used for a continuous long-term regional climate simulation over Europe. Built upon the Limited-Area Mode of ICON (ICON-LAM), ICON-CLM (ICON in Climate Limited-area Mode, hereafter ICON-CLM, available in ICON release version 2.6.1) is an adaptation for climate applications. A first version of ICON-CLM is now available and has already been integrated into a starter package (ICON-CLM_SP_beta1). The starter package provides users with a technical infrastructure that facilitates long-term simulations as well as model evaluation and test routines. ICON-CLM and ICON-CLM_SP were successfully installed and tested on two different computing systems. Tests with different domain decompositions showed bit-identical results, and no systematic outstanding differences were found in the results with different model time steps. ICON-CLM was also able to reproduce the large-scale atmospheric information from the global driving model. Comparison was done between ICON-CLM and the COnsortium for Small-scale MOdeling (COSMO)-CLM (the recommended model configuration by the CLM-Community) performance. For that, an evaluation run of ICON-CLM with ERA-Interim boundary conditions was carried out with the setup similar to the COSMO-CLM recommended optimal setup. ICON-CLM results showed biases in the same range as those of COSMO-CLM for all evaluated surface variables. While this COSMO-CLM simulation was carried out with the latest model version which has been developed and was carefully tuned for climate simulations on the European domain, ICON-CLM was not tuned yet. Nevertheless, ICON-CLM showed a better performance for air temperature and its daily extremes, and slightly better performance for total cloud cover. For precipitation and mean sea level pressure, COSMO-CLM was closer to observations than ICON-CLM. However, as ICON-CLM is still in the early stage of development, there is still much room for improvement. %0 journal article %@ 1814-9324 %A Bothe, O., Zorita, E. %D 2021 %J Climate of the Past %N 2 %P 721-751 %R doi:10.5194/cp-17-721-2021 %T Technical note: Considerations on using uncertain proxies in the analogue method for spatiotemporal reconstructions of millennial-scale climate %U https://doi.org/10.5194/cp-17-721-2021 2 %X We discuss the benefits and limitations of this approach. The results highlight the potential of the analogue method to reconstruct the climate from the deglaciation up to the late Holocene. However, in the present case, the reconstructions show little variability of their central estimates but large uncertainty ranges. The reconstruction by analogue provides not only a regional average record but also allows assessing the spatial climate field compliant with the used proxy predictors. These fields reveal that uncertainties are also locally large. Our results emphasize the ambiguity of reconstructions from spatially sparse and temporally uncertain, irregularly sampled proxies. %0 journal article %@ 2296-7745 %A Li, D., Staneva, J., Bidlot, J., Grayek, S., Zhu, Y., Yin, B. %D 2021 %J Frontiers in Marine Science %P 613913 %R doi:10.3389/fmars.2021.613913 %T Improving Regional Model Skills During Typhoon Events: A Case Study for Super Typhoon Lingling Over the Northwest Pacific Ocean %U https://doi.org/10.3389/fmars.2021.613913 %X The ability of forecasting systems to simulate tropical cyclones is still insufficient, and currently, there is an increased interest in improving model performance for intense tropical cyclones. In this study, the impact of reducing surface drag at high wind speeds on modeling wind and wave conditions during the super Typhoon Lingling event over the northwest Pacific Ocean in 2019 is investigated. The model response with respect to the parameterization for momentum exchange at the ocean surface is demonstrated using a fully coupled regional atmosphere model (the Consortium for Small-Scale Modeling-Climate Limited-area Modeling, CCLM) and a wind wave model (WAM). The active two-way coupling between the atmosphere and ocean waves model is enabled through the introduction of sea state-dependent surface drag into the CCLM and updated winds into the WAM. The momentum exchange with the sea surface is modeled via the dependency of the roughness length (Z0) on the surface stress itself and, when applicable, on the wind speed. Several high-resolution runs are performed using one-way or two-way fully coupled regional atmosphere-wave (CCLM-WAM) models. The model simulations are assessed against the best track data as well as against buoy and satellite observations. The results show that the spectral nudging technique can improve the model’s ability to capture the large-scale circulation, track and intensity of Typhoon Lingling at regional scales. Under the precondition of large-scale constraining, the two-way coupling simulation with the proposed new roughness parameterization performs much better than the simulations used in older studies in capturing the maximum wind speed of Typhoon Lingling due to the reduced drag at extreme wind conditions for the new Z0. %0 journal article %@ 0304-3800 %A Krishna, S., Ulloa, H., Kerimoglu, O., Minaudo, C., Anneville, O., Wüest, A. %D 2021 %J Ecological Modelling %P 109401 %R doi:10.1016/j.ecolmodel.2020.109401 %T Model-based data analysis of the effect of winter mixing on primary production in a lake under reoligotrophication %U https://doi.org/10.1016/j.ecolmodel.2020.109401 %X According to our results, the simulated surface mixed layer depth is deeper and heat loss from the lake and turbulent kinetic energy in the water column are much higher in winter 2012 than that in 2013, pointing to a cooling-driven, deep mixing in the lake in 2012. We found significant differences in internal phosphorus loads in the epilimnion between the two years, with estimates for 2012 being higher than those for 2013. ERGOM predicts weak nutrient limitation on phytoplankton and higher growth rates in 2012. Apparently, the deep mixing event led to high turnover of nutrients (particularly dissolved inorganic phosphate) to the productive surface layers, and a massive algal bloom developed later in the productive season. In contrary, the turnover of nutrients in 2013 was weak and consequently the PP was low. Our findings demonstrate the utility of a coupled physical–biological model framework for the investigation of the meteorological and physical controls of PP dynamics in aquatic systems. %0 journal article %@ 2296-7745 %A Schulz-Stellenfleth, J., Foerderreuther, S., Horstmann, J., Staneva, J. %D 2021 %J Frontiers in Marine Science %P 648266 %R doi:10.3389/fmars.2021.648266 %T Optimisation of Parameters in a German Bight Circulation Model by 4DVAR Assimilation of Current and Water Level Observations %U https://doi.org/10.3389/fmars.2021.648266 %X Uncertain parameters in a 3D barotropic circulation model of the German Bight are estimated with a variational optimisation approach. Surface current measurements from a high frequency (HF) radar are used in combination with acoustic Doppler current profiler (ADCP) and tide gauge observations as input for a 4DVAR assimilation scheme. The required cost function gradients are estimated using an adjoint model code. The focus of the study is on systematic errors of the model with the control vector including parameters of the bathymetry, bottom roughness, open boundary forcing, meteorological forcing as well as the turbulence model. The model uses the same bathymetry, open boundary forcing, and metereological forcing as the operational model run at the Federal Maritime and Hydrographic Agency (BSH). The baroclinic BSH model is used as a reference to put the performance of the optimised model into perspective. It is shown that the optimised model has better agreement with HF radar data and tide gauge observations both within the fortnight training period and the test period 1 month later. Current profile measurements taken at two platforms indicate that both models have comparable error magnitudes at those locations. The optimised model was also compared with independent drifter data. In this case, drifter simulations based on the BSH model and the respective operational drift model including some surface wave effects were used as a reference. Again, these comparison showed very similar results overall, with some larger errors of the tuned model in very shallow areas, where no observations were used for the tuning and surface wave effects, which are only explicitly considered in the BSH model, play a more important role. The tuned model seems to be slightly more dissipative than the BSH model with more energy entering through the western boundary and less energy leaving toward the north. It also became evident that the 4DVAR cost function minimisation process is complicated by momentum advection, which leads to non-differentiable dependencies of the model with respect to the control vector. It turned out that the omission of momentum advection in the adjoint code still leads to robust estimates of descent directions. %0 journal article %@ 2077-1312 %A Bärfuss, K., Schulz-Stellenfleth, J., Lampert, A. %D 2021 %J Journal of Marine Science and Engineering %N 6 %P 644 %R doi:10.3390/jmse9060644 %T The Impact of Offshore Wind Farms on Sea State Demonstrated by Airborne LiDAR Measurements %U https://doi.org/10.3390/jmse9060644 6 %X The increasing number of wind farms installed in the North Sea has an impact on the downstream wind speed. This has been hypothesized as well for sea state properties. Wave effects can be expected in particular in fetch-limited conditions with offshore wind directions. With systematic flights deploying an airborne laser scanner, these impacts are shown directly for the first time. The flights were conducted perpendicular to the main wind direction upstream and downstream of the cluster of the offshore wind parks Amrumbank West, Nordsee Ost, and Meerwind Süd/Ost. The flight legs covered the area potentially influenced by the wind parks and the undisturbed area next to the wind parks. The analysis of the spectral energy distribution shows a re-distribution of the wave energy in the downstream area with enhanced energy at smaller wavelengths. The effect is still clearly visible at a distance of 55 km. As the sea surface constitutes the link between the atmosphere and the ocean, it is very likely that wind parks modify the properties of the water column as well. %0 journal article %@ 0964-5691 %A Gilek, M., Armoskaite, A., Gee, K., Saunders, F., Tafon, R., Zaucha, J. %D 2021 %J Ocean & Coastal Management %P 105618 %R doi:10.1016/j.ocecoaman.2021.105618 %T In search of social sustainability in marine spatial planning: A review of scientific literature published 2005–2020 %U https://doi.org/10.1016/j.ocecoaman.2021.105618 %X A number of commentators have argued that up until now marine/maritime spatial planning (MSP) research and practice have been dominated by blue economy and environmental concerns and have tended to neglect what might be regarded as social sustainability concerns. To gain more insight into the character and extent of such a gap, as well as how to address it, this article examines how social sustainability has been addressed in peer reviewed scientific articles on MSP between 2005 and 2020. Using search terms such as participation, democracy, social inclusion, social cohesion, equity we systematically identify and review 310 scientific articles that address diverse social sustainability concerns within MSP and marine governance. The review showed that very few papers systematically conceptualised or developed a coherent framework for engaging with social sustainability. Instead, they mostly addressed particular social concerns including participation and engagement, equity and social justice, socio-cultural values and preferences. Marine management and planning efficiency, as well as related instrumental framings of the merits of participation were the key arguments for including these dimensions of social sustainability in MSP. In terms of how to better include social sustainability in MSP, most attention was given to social-cultural mapping and ways to improve social inclusion/participation while also redressing exclusion and maldistribution of outcomes in MSP practice. We conclude that there is a need to deepen and diversify MSP inquiry with respect to social sustainability. In particular, scholars would do well to delve deeper and more broadly in social science literature to find inspiration on ways to understand and elucidate social issues. Here, the enormous body of relevant work on justice, power, critical institutionalism, political ecology and terrestrial planning literatures has hardly been tapped. It is also evident from this review that there is a need for both the academic and practice-based communities to more comprehensively address how the multidimensions of social sustainability interact with each other, as well as with economic and environmental aspects of marine planning and governance. Based on these observations, we highlight a set of suggestions on how to develop MSP research and practice on social sustainability. Most importantly, we argue that more in-depth co-production, linking scholars, practitioners and society actors, is needed. %0 journal article %@ 2077-1312 %A Ciliberti, S.A., Grégoire, M., Staneva, J., Palazov, A., Coppini, G., Lecci, R., Peneva, E., Matreata, M., Marinova, V., Masina, S., Pinardi, N., Jansen, E., Lima, L., Aydoğdu, A., Creti’, S., Stefanizzi, L., Azevedo, D., Causio, S., Vandenbulcke, L., Capet, A., Meulders, C., Ivanov, E., Behrens, A., Ricker, M., Gayer, G., Palermo, F., Ilicak, M., Gunduz, M., Valcheva, N., Agostini, P. %D 2021 %J Journal of Marine Science and Engineering %N 10 %P 1146 %R doi:10.3390/jmse9101146 %T Monitoring and Forecasting the Ocean State and Biogeochemical Processes in the Black Sea: Recent Developments in the Copernicus Marine Service %U https://doi.org/10.3390/jmse9101146 10 %X The Black Sea Monitoring and Forecasting Center (BS-MFC) is the European reference service for the provision of ocean analyses, forecasts, and reanalyses in the Black Sea basin. It is part of the Copernicus Marine Environment and Monitoring Service (CMEMS) and ensures a high level of efficiency in terms of operations, science, and technology for predictions and the monitoring of physical and biogeochemical processes in the Black Sea. The operational BS-MFC framework is based on state-of-the-art numerical models for hydrodynamics, biogeochemistry, and waves; analysis, forecast, and reanalysis are provided on a spatial grid with about 3 km of horizontal resolution that covers the whole Black Sea basin (the Azov Sea is not included). The scientific assessment of BS-MFC products is performed by implementing a product quality dashboard that provides pre-qualification and operational model skills according to GODAE/OceanPredict standards. Novel interfaces based on high-resolution models are part of the scientific development plan to ensure a strong connection with the nearest seas from a modelling point of view, in particular with the Mediterranean Sea. To improve forecasting skills, dedicated online coupled systems are being developed, which involve physics, biogeochemistry, and waves together with the atmosphere and, in the future, with ensemble forecasting methodologies and river-ocean interfaces. %0 journal article %@ 2698-4016 %A Carvalho-Oliveira, J., Borchert, L., Duchez, A., Dobrynin, M., Baehr, J. %D 2021 %J Weather and Climate Dynamics %N 3 %P 739-757 %R doi:10.5194/wcd-2-739-2021 %T Subtle influence of the Atlantic Meridional Overturning Circulation (AMOC) on seasonal sea surface temperature (SST) hindcast skill in the North Atlantic %U https://doi.org/10.5194/wcd-2-739-2021 3 %X We investigate the impact of the strength of the Atlantic Meridional Overturning Circulation (AMOC) at 26∘ N on the prediction of North Atlantic sea surface temperature anomalies (SSTAs) a season ahead. We test the dependence of sea surface temperate (SST) predictive skill in initialised hindcasts on the phase of the AMOC at 26∘N, invoking a seesaw mechanism driven by AMOC fluctuations, with positive SSTAs north of 26∘ N and negative SSTAs south of 26∘ N after a strong AMOC and vice versa. We use initialised simulations with the MPI-ESM-MR (where MR is mixed resolution) seasonal prediction system. First, we use an assimilation experiment between 1979–2014 to confirm that the AMOC leads a SSTA dipole pattern in the tropical and subtropical North Atlantic, with the strongest AMOC fingerprints after 2–4 months. Going beyond previous studies, we find that the AMOC fingerprint has a seasonal dependence and is sensitive to the length of the observational window used, i.e. stronger over the last decade than for the entire time series back to 1979. We then use a set of ensemble hindcast simulations with 30 members, starting each February, May, August and November between 1982 and 2014. We compare the changes in skill between composites based on the AMOC phase a month prior to each start date to simulations without considering the AMOC phase and find subtle influence of the AMOC mechanism on seasonal SST prediction skill. We find higher subtropical SST hindcast skill at a 2–4-month lead time for June–July–August (JJA) SSTA composites based on the AMOC phase at May start dates than for the full time period. In other regions and seasons, we find a negligible impact of the AMOC seesaw mechanism on seasonal SST predictions due to atmospheric influence, calling for caution when considering such a mechanism. Our method shows that, for May start dates following strong AMOC phases, summer SST hindcast skill over the subtropics increases significantly compared to that of weak AMOC phases. This suggests that in the assessment of SST skill for a season ahead an eye should be kept on the initial AMOC state. %0 journal article %@ 2212-9790 %A Döring, M., Ratter, B. %D 2021 %J Maritime Studies %N 3 %P 317-327 %R doi:10.1007/s40152-021-00239-w %T “I show you my coast…” - a relational study of coastscapes in the North Frisian Wadden Sea %U https://doi.org/10.1007/s40152-021-00239-w 3 %X In recent years, there has been an upsurge in research on relational approaches in geography and in the study of cultural landscapes. Following these strands of research, the relationality of human beings with their natural environments has been highlighted, emphasising the various ways people engage with their lifeworlds. This development is motivated by the perceived need to analytically expand landscape research towards a more-than-representational point of view, challenging the still prevalent dichotomy of nature and culture. The paper takes these insights as a starting point and provides an insight into a more-than-representational understanding of coastscapes that is combined with a more-than-representational understanding of language. Its aim is threefold: to theoretically engage with a more-than-representational and enlanguaged understanding of coastscapes; to explore the relevance of mobile methods for such an approach; and to empirically illustrate the emotive and relational bonds coastal dwellers form with their littoral environs. To capture the dynamism of a more-than-representational understanding that coastal dwellers develop with their coastscape, walking interviews were conducted in the district of North Frisia (Germany). All interviews were examined following a grounded approach and refined by a linguistic in-depth investigation. The analysis revealed four prevailing interpretative repertoires reconfiguring the boundary between nature and culture. They exhibit what we call a coast-multiple that adds to coastal nature-society-mixes which might be of interest for future coastal management at the German Wadden Sea. %0 journal article %@ 1748-9326 %A Borchert, L., Koul, V., Menary, M., Befort, D., Swingedouw, D., Sgubin, G., Mignot, J. %D 2021 %J Environmental Research Letters %N 10 %P 104017 %R doi:10.1088/1748-9326/ac20f5 %T Skillful decadal prediction of unforced southern European summer temperature variations %U https://doi.org/10.1088/1748-9326/ac20f5 10 %X We assess the capability of decadal prediction simulations from the Coupled Model Intercomparison Project phase 6 (CMIP6) archive to predict European summer temperature during the period 1970-2014. Using a multi-model ensemble average, we show that Southern European (SEU) summer temperatures are highly predictable for up to ten years in CMIP6. Much of this predictive skill, is related to the externally forced response: historical simulations explain about 90% of observed SEU summer temperature variance. Prediction skill for the unforced signal of SEU summer temperature is low: initialized model simulations explain less than 10% of observed variance after removing the externally forced response. An observed link between unforced SEU summer temperature and preceding spring Eastern North Atlantic - Mediterranean sea surface temperature (SST) motivates the application of a dynamical-statistical model to overcome the low summer temperature skill over Europe. This dynamical-statistical model uses dynamical spring SST predictions to predict European summer temperature, and significantly increases decadal prediction skill of unforced European summer temperature variations, showing significant prediction skill for unforced Southern European summer temperature 2-9 years ahead. As a result, dynamical-statistical models can benefit the decadal prediction of variables with initially limited skill beyond the forcing, such as summer temperature over Europe. %0 journal article %@ 2169-9275 %A Zhang, W., Neumann, A., Daewel, U., Wirtz, K., van Beusekom, J., Eisele, A., Ma, M., Schrum, C. %D 2021 %J Journal of Geophysical Research : Oceans %N 10 %P e2020JC016995 %R doi:10.1029/2020JC016995 %T Quantifying Importance of Macrobenthos for Benthic-Pelagic Coupling in a Temperate Coastal Shelf Sea %U https://doi.org/10.1029/2020JC016995 10 %X Benthic oxygen fluxes consist mostly of advective and diffusive terms. Both terms in the German Bight exhibit a prominent annual cycle but with opposite variation patterns. To understand the driving mechanisms quantitatively, a novel 3-D benthic-pelagic coupled model resolving interactions among macrobenthos, bioturbation, oxygen consumption, and carbon early diagenesis was applied to reconstruct the benthic states. Simulation results show a satisfactory agreement with field data and reveal that the benthic oxygen flux is determined by not only pelagic drivers but also by internal dynamics associated with the interaction between organic carbon and macrobenthos, and bedform morphodynamics. Variation of advective flux, characterized by summer-low and winter-high, is mainly driven by hydrodynamics and bedform morphodynamics, while variation of diffusive flux, featured by summer-high and winter-low, is a compound effect of pelagic and benthic drivers with a dominant control by macrobenthos through bioturbation. The role of bioturbation in benthic oxygen consumption is twofold: (a) on the one hand, it alters the particulate organic carbon (POC) distribution in surface sediments, thereby changing the availability of POC to oxygen consumption; (b) on the other hand, it mixes oxygen down into sediments, thereby facilitating oxygen consumption. Our results indicate that the first role prevails in sandy seafloor characterized by energetic hydrodynamics, while the second role becomes increasingly important along with a weakening of bottom currents. We found that bioturbation contributes up to 87% urn:x-wiley:21699275:media:jgrc24733:jgrc24733-math-0001 4% and 55% urn:x-wiley:21699275:media:jgrc24733:jgrc24733-math-0002 8% of the total benthic oxygen fluxes in muddy seabed and at a regional scale (the German Bight), respectively. %0 journal article %@ 1680-7316 %A Matthias, V., Quante, M., Arndt, J., Badeke, R., Fink, L., Petrik, R., Feldner, J., Schwarzkopf, D., Link, E.-M., Ramacher, M., Wedemann, R. %D 2021 %J Atmospheric Chemistry and Physics %N 18 %P 13931-13971 %R doi:10.5194/acp-21-13931-2021 %T The role of emission reductions and the meteorological situation for air quality improvements during the COVID-19 lockdown period in central Europe %U https://doi.org/10.5194/acp-21-13931-2021 18 %X The lockdown can be seen as a big experiment about air quality improvements that can be achieved through drastic traffic emission reductions. From this investigation, it can be concluded that NO2 concentrations can be largely reduced, but effects on annual average values are small when the measures last only a few weeks. Secondary pollutants like ozone and PM2.5 depend more strongly on weather conditions and show a limited response to emission changes in single sectors. %0 journal article %@ 1991-959X %A Telteu, C.-E., Müller Schmied, H., Thiery, W., Leng, G., Burek, P., Liu, X., Boulange, J.E.S., Andersen, L.S., Grillakis, M., Gosling, S.N., Satoh, Y., Rakovec, O., Stacke, T., Chang, J., Wanders, N., Shah, H.L., Trautmann, T., Mao, G., Hanasaki, N., Koutroulis, A., Pokhrel, Y., Samaniego, L., Wada, Y., Mishra, V., Liu, J., Döll, P., Zhao, F., Gädeke, A., Rabin, S.S., Herz, F. %D 2021 %J Geoscientific Model Development %N 6 %P 3843-3878 %R doi:10.5194/gmd-14-3843-2021 %T Understanding each other's models: an introduction and a standard representation of 16 global water models to support intercomparison, improvement, and communication %U https://doi.org/10.5194/gmd-14-3843-2021 6 %X Global water models (GWMs) simulate the terrestrial water cycle on the global scale and are used to assess the impacts of climate change on freshwater systems. GWMs are developed within different modelling frameworks and consider different underlying hydrological processes, leading to varied model structures. Furthermore, the equations used to describe various processes take different forms and are generally accessible only from within the individual model codes. These factors have hindered a holistic and detailed understanding of how different models operate, yet such an understanding is crucial for explaining the results of model evaluation studies, understanding inter-model differences in their simulations, and identifying areas for future model development. This study provides a comprehensive overview of how 16 state-of-the-art GWMs are designed. We analyse water storage compartments, water flows, and human water use sectors included in models that provide simulations for the Inter-Sectoral Impact Model Intercomparison Project phase 2b (ISIMIP2b). We develop a standard writing style for the model equations to enhance model intercomparison, improvement, and communication. In this study, WaterGAP2 used the highest number of water storage compartments, 11, and CWatM used 10 compartments. Six models used six compartments, while four models (DBH, JULES-W1, Mac-PDM.20, and VIC) used the lowest number, three compartments. WaterGAP2 simulates five human water use sectors, while four models (CLM4.5, CLM5.0, LPJmL, and MPI-HM) simulate only water for the irrigation sector. We conclude that, even though hydrological processes are often based on similar equations for various processes, in the end these equations have been adjusted or models have used different values for specific parameters or specific variables. The similarities and differences found among the models analysed in this study are expected to enable us to reduce the uncertainty in multi-model ensembles, improve existing hydrological processes, and integrate new processes. %0 journal article %@ 2190-4979 %A Gröger, M., Dieterich, C., Haapala, J., Ho-Hagemann, H., Hagemann, S., Jakacki, J., May, W., Meier, H., Miller, P., Rutgersson, A., Wu, L. %D 2021 %J Earth System Dynamics %N 3 %P 939-973 %R doi:10.5194/esd-12-939-2021 %T Coupled regional Earth system modeling in the Baltic Sea region %U https://doi.org/10.5194/esd-12-939-2021 3 %X Many regional stand-alone ocean and atmosphere models are tuned to suitably represent present-day climatologies rather than to accurately simulate climate change. Therefore, more research is required into how the regional climate sensitivity (e.g., the models' response to a given change in global mean temperature) is affected by coupling and how the spread is altered in multi-model and multi-scenario ensembles of coupled models compared with uncoupled ones. %0 journal article %@ 1991-959X %A Kerimoglu, O., Anugerahanti, P., Smith, S. %D 2021 %J Geoscientific Model Development %N 10 %P 6025-6047 %R doi:10.5194/gmd-14-6025-2021 %T FABM-NflexPD 1.0: assessing an instantaneous acclimation approach for modeling phytoplankton growth %U https://doi.org/10.5194/gmd-14-6025-2021 10 %X Coupled physical–biogeochemical models can generally reproduce large-scale patterns of primary production and biogeochemistry, but they often underestimate observed variability and gradients. This is partially caused by insufficient representation of systematic variations in the elemental composition and pigment density of phytoplankton. Although progress has been made through approaches accounting for the dynamics of phytoplankton composition with additional state variables, formidable computational challenges arise when these are applied in spatially explicit setups. The instantaneous acclimation (IA) approach addresses these challenges by assuming that Chl:C:nutrient ratios are instantly optimized locally (within each modeled grid cell, at each time step), such that they can be resolved as diagnostic variables. Here, we present the first tests of IA in an idealized 1-D setup: we implemented the IA in the Framework for Aquatic Biogeochemical Models (FABM) and coupled it with the General Ocean Turbulence Model (GOTM) to simulate the spatiotemporal dynamics in a 1-D water column. We compare the IA model against a fully dynamic, otherwise equivalently acclimative (dynamic acclimation; DA) variant with an additional state variable and a third, non-acclimative and fixed-stoichiometry (FS) variant. We find that the IA and DA variants, which require the same parameter set, behave similarly in many respects, although some differences do emerge especially during the winter–spring and autumn–winter transitions. These differences however are relatively small in comparison to the differences between the DA and FS variants, suggesting that the IA approach can be used as a cost-effective improvement over a fixed-stoichiometry approach. Our analysis provides insights into the roles of acclimative flexibilities in simulated primary production and nutrient drawdown rates, seasonal and vertical distribution of phytoplankton biomass, formation of thin chlorophyll layers and stoichiometry of detrital material. %0 journal article %@ 0025-3227 %A Wilckens, H., Miramontes, E., Schwenk, T., Artana, C., Zhang, W., Piola, A., Baqueseg, M., Provost, C., Hernández-Molina, J., Felgendreher, M., Spieß, V., Kasten, S. %D 2021 %J Marine Geology %P 106539 %R doi:10.1016/j.margeo.2021.106539 %T The erosive power of the Malvinas Current: Influence of bottom currents on morpho-sedimentary features along the northern Argentine margin (SW Atlantic Ocean) %U https://doi.org/10.1016/j.margeo.2021.106539 %X The contouritic features include large contourite terraces (La Plata Terrace, Ewing Terrace) and an abraded surface connecting the terraces, as well as smaller erosional and depositional features like moats, erosion surfaces on the Ewing Terrace, sediment waves and contourite drifts. Measured and modelled near-bottom currents are vigorous (up to 63 cm/s at 150–200 m above the seafloor) where abraded surfaces and moats are present, and relatively weak (below 30 cm/s) on the La Plata Terrace and the Ewing Terrace. Generally, bottom currents follow the upper and middle slope morphology. Decreasing velocity of water masses flowing northward leads to less erosion and finer sediment deposits. ADCP data and the hydrodynamic model show the formation of eddies near the seafloor which probably lead to the small erosion surfaces on the Ewing Terrace, even though it is mainly a depositional environment. Overall, this study contributes to a better understanding of the formation of CDS and can help future reconstructions of past ocean conditions based on sedimentary structures. %0 journal article %@ 2071-1050 %A Przedrzymirska, J., Zaucha, J., Calado, H., Lukic, I., Bocci, M., Ramieri, E., Varona, M.C., Barbanti, A., Depellegrin, D., De Sousa Vergílio, M., Schultz-Zehden, A., Onyango, V., Papaioannou, E., Buck, B.H., Krause, G., Felix Schupp, M., Läkamp, R., Szefler, K., Michałek, M., Maniopoulou, M., Vassilopoulou, V., Kyriazi, Z., Gawlikowska-Hueckel, K., Szultka, S., Orobello, C., Gee, K., Buchanan, B., Lazić, M. %D 2021 %J Sustainability %N 15 %P 8159 %R doi:10.3390/su13158159 %T Multi-Use of the Sea as a Sustainable Development Instrument in Five EU Sea Basins %U https://doi.org/10.3390/su13158159 15 %X This paper examines the concept of maritime multi-use as a territorial/SPATIAL governance instrument for the enhancement of sustainable development in five EU sea basins. Multi-use (MU) is expected to enhance the productivity of blue economy sectors, as well as deliver additional socio-economic benefits related to the environmental and social dimensions of sustainable development. The paper provides a definition of maritime multi-use and identifies the multi-uses with the highest potential in EU sea basins. In each sea basin, multi-use plays a different role as concerns sustainable development. For the Eastern Baltic Sea, the Mediterranean Sea and the Black Sea, the MU focus should remain on the environmental pillar of sustainable development. In the North Sea, North Atlantic and Western Baltic Sea, addressing social sustainability seems a key precondition for success of MU in enhancement of sustainable spatial development at sea. Moreover, it has been suggested to introduce MU key global strategies such as SDGs or Macroregional strategies and action plans and to supplement maritime spatial planning with sectoral incentives and educational efforts as key vehicles supporting MU. The paper concludes by identifying aspects which, in order to inform maritime spatial planning and maritime governance regarding a more conscious application of the aforementioned concept, require further investigation. Key tasks are related to: more profound evaluation of performance of policies supporting MUs, researching the impact of MU on societal goals and on the MU costs and benefits, including external ones, and finally identifying the impact of MU on the development of various sectors and regions on land. %0 journal article %@ 2041-1723 %A David, G., Henning, A., Ratter, B., Roeber, V., Zahid, Schlurmann, T. %D 2021 %J Nature Communications %N 1 %P 5882 %R doi:10.1038/s41467-021-26082-5 %T Considering socio-political framings when analyzing coastal climate change effects can prevent maldevelopment on small islands %U https://doi.org/10.1038/s41467-021-26082-5 1 %X Adapting to climate change and sea level rise is challenging on small islands. False adaptation can lead to adverse impacts on natural and societal dynamics. Therefore, an interdisciplinary perspective on the interaction of natural dynamics, societal demands, and political decisions is crucial. In this sense, this study scrutinizes coastal processes and socio-political dimensions of erosion on the reef island Fuvahmulah, the Maldives. The national government and Fuvahmulah’s population have an opposed perception and attribution of the drivers and processes behind Fuvahmulah’s most pressing coastal issue – coastal erosion. To review these perceptions, natural dynamics are recreated with process-based methods and discussed regarding present and projected marine pressures. Population surveys and interviews with actors in coastal development complement the physical insights into erosion on Fuvahmulah and describe the socio-political dimension of climate change adaptation on small islands. This interdisciplinary approach demonstrates how small-islands’ adaptive capacities are typically impaired and disclose the potential of local knowledge to overcome maldevelopment. %0 journal article %@ 0301-4797 %A Stelzenmüller, V., Comier, R., Gee, K., Shucksmith, R., Gubbins, M., Yates, K., Morf, A., Nic Aonghusa, C., Mikkelsen, E., Tweddle, J., Pecceu, E., Kannen, A., Clarke, S. %D 2021 %J Journal of Environmental Management %N 2 %P 111545 %R doi:10.1016/j.jenvman.2020.111545 %T Evaluation of marine spatial planning requires fit for purpose monitoring strategies %U https://doi.org/10.1016/j.jenvman.2020.111545 2 %X Marine spatial planning (MSP) has rapidly become the most widely used integrated, place-based management approach in the marine environment. Monitoring and evaluation of MSP is key to inform best practices, adaptive management and plan iteration. While standardised evaluation frameworks cannot be readily applied, accounting for evaluation essentials such as the definition of evaluation objectives, indicators and stakeholder engagement of stakeholders is a prerequisite for meaningful evaluation outcomes. By way of a literature review and eleven practical MSP case studies, we analysed present day trends in evaluation approaches and unravelled the adoption of evaluation essentials for three categories for monitoring and evaluation for plan making, plan outcomes, and policy implementation. We found that at a global scale the focus of MSP evaluation has shifted over the past decade from evaluating predominantly plan outcomes towards the evaluation of plan making. Independent of the scope of the evaluation, evaluation approaches varied greatly from formal and structured processes, building for instance on MSP goals and objectives, to informal processes based on stakeholder interviews. We noted a trend in the adoption of formalised approaches where MSP evaluations have increasingly become linked to MSP policy goals and objectives. However, the enhanced use of MSP objectives and indicators did not result in a more straightforward reporting of outcomes, e.g. such as the achievement of specific MSP objectives. Overall, we found weak linkages between defined MSP objectives, indicators and available monitoring data. While the apparent shift towards a focus on objectives is promising, we highlight the need of fit-for-purpose monitoring data to enable effective evaluation of those objectives. Hence, effective MSP and adaptive management processes require customised and concurrent monitoring and evaluation strategies and procedures. We argue that evaluation processes would also benefit from a better understanding of the general environmental, socio-economic and socio-cultural effects of MSP. Therefore, to understand better environmental effects of MSP, we praise that forthcoming MSP processes need to deepen the understanding and considerations of cause-effect pathways between human activities and changes of ecosystem state through the adoption of targeted cumulative effects assessments. %0 journal article %@ 1991-959X %A Stacke, T., Hagemann, S. %D 2021 %J Geoscientific Model Development %N 12 %P 7795-7816 %R doi:10.5194/gmd-14-7795-2021 %T HydroPy (v1.0): a new global hydrology model written in Python %U https://doi.org/10.5194/gmd-14-7795-2021 12 %X Global hydrological models (GHMs) are a useful tool in the assessment of the land surface water balance. They are used to further the understanding of interactions between water balance components and their past evolution as well as potential future development under various scenarios. While GHMs have been part of the hydrologist's toolbox for several decades, the models are continuously being developed. In our study, we present the HydroPy model, a revised version of an established GHM, the Max Planck Institute for Meteorology's Hydrology Model (MPI-HM). Being rewritten in Python, the new model requires much less effort in maintenance, and due to its flexible infrastructure, new processes can be easily implemented. Besides providing a thorough documentation of the processes currently implemented in HydroPy, we demonstrate the skill of the model in simulating the land surface water balance. We find that evapotranspiration is reproduced realistically for the majority of the land surface but is underestimated in the tropics. The simulated river discharge correlates well with observations. Biases are evident for the annual accumulated discharge; however, they can – at least to some extent – be attributed to discrepancies between the meteorological model forcing data and the observations. Finally, we show that HydroPy performs very similarly to MPI-HM and thus conclude the successful transition from MPI-HM to HydroPy. %0 journal article %@ 2522-5839 %A Irrgang, C., Boers, N., Sonnewald, M., Barnes, E., Kadow, C., Staneva, J., Saynisch-Wagner, J. %D 2021 %J Nature Machine Intelligence %N 8 %P 667-674 %R doi:10.1038/s42256-021-00374-3 %T Towards neural Earth system modelling by integrating artificial intelligence in Earth system science %U https://doi.org/10.1038/s42256-021-00374-3 8 %X Earth system models (ESMs) are our main tools for quantifying the physical state of the Earth and predicting how it might change in the future under ongoing anthropogenic forcing. In recent years, however, artificial intelligence (AI) methods have been increasingly used to augment or even replace classical ESM tasks, raising hopes that AI could solve some of the grand challenges of climate science. In this Perspective we survey the recent achievements and limitations of both process-based models and AI in Earth system and climate research, and propose a methodological transformation in which deep neural networks and ESMs are dismantled as individual approaches and reassembled as learning, self-validating and interpretable ESM–network hybrids. Following this path, we coin the term neural Earth system modelling. We examine the concurrent potential and pitfalls of neural Earth system modelling and discuss the open question of whether AI can bolster ESMs or even ultimately render them obsolete. %0 journal article %@ 2296-6463 %A Bonaduce, A., Cipollone, A., Johannessen, J., Staneva, J., Raj, R., Aydogdu, A. %D 2021 %J Frontiers in Earth Science %P 724879 %R doi:10.3389/feart.2021.724879 %T Ocean Mesoscale Variability: A Case Study on the Mediterranean Sea From a Re-Analysis Perspective %U https://doi.org/10.3389/feart.2021.724879 %X The mesoscale variability in the Mediterranean Sea is investigated through eddy detection techniques. The analysis is performed over 24 years (1993–2016) considering the three-dimensional (3D) fields from an ocean re-analysis of the Mediterranean Sea (MED-REA). The objective is to achieve a fit-for-purpose assessment of the 3D mesoscale eddy field. In particular, we focus on the contribution of eddy-driven anomalies to ocean dynamics and thermodynamics. The accuracy of the method used to disclose the 3D eddy contributions is assessed against pointwise in-situ measurements and observation-based data sets. Eddy lifetimes ≥ 2 weeks are representative of the 3D mesoscale field in the basin, showing a high probability (> 60%) of occurrence in the areas of the main quasi-stationary mesoscale features. The results show a dependence of the eddy size and thickness on polarity and lifetime: anticyclonic eddies (ACE) are significantly deeper than cyclonic eddies (CE), and their size tends to increase in long-lived structures which also show a seasonal variability. Mesoscale eddies result to be a significant contribution to the ocean dynamics in the Mediterranean Sea, as they account for a large portion of the sea-surface height variability at temporal scales longer than 1 month and for the kinetic energy (50–60%) both at the surface and at depth. Looking at the contributions to ocean thermodynamics, the results exhibit the existence of typical warm (cold) cores associated with ACEs (CEs) with exceptions in the Levantine basin (e.g., Shikmona gyre) where a structure close to a mode-water ACE eddy persists with a positive salinity anomaly. In this area, eddy-induced temperature anomalies can be affected by a strong summer stratification in the surface water, displaying an opposite sign of the anomaly whether looking at the surface or at depth. The results show also that temperature anomalies driven by long-lived eddies (≥ 4 weeks) can affect up to 15–25% of the monthly variability of the upper ocean heat content in the Mediterranean basin. %0 journal article %@ 2296-7745 %A Liu, F., Daewel, U., Samuelsen, A., Brune, S., Hanz, U., Pohlmann, H., Baehr, J., Schrum, C. %D 2021 %J Frontiers in Marine Science %P 703297 %R doi:10.3389/fmars.2021.703297 %T Can Environmental Conditions at North Atlantic Deep-Sea Habitats Be Predicted Several Years Ahead? Taking Sponge Habitats as an Example %U https://doi.org/10.3389/fmars.2021.703297 %X Predicting the ambient environmental conditions in the coming several years to one decade is of key relevance for elucidating how deep-sea habitats, like for example sponge habitats, in the North Atlantic will evolve under near-future climate change. However, it is still not well known to what extent the deep-sea environmental properties can be predicted in advance. A regional downscaling prediction system is developed to assess the potential predictability of the North Atlantic deep-sea environmental factors. The large-scale climate variability predicted with the coupled Max Planck Institute Earth System Model with low-resolution configuration (MPI-ESM-LR) is dynamically downscaled to the North Atlantic by providing surface and lateral boundary conditions to the regional coupled physical-ecosystem model HYCOM-ECOSMO. Model results of two physical fields (temperature and salinity) and two biogeochemical fields (concentrations of silicate and oxygen) over 21 sponge habitats are taken as an example to assess the ability of the downscaling system to predict the interannual to decadal variations of the environmental properties based on ensembles of retrospective predictions over the period from 1985 to 2014. The ensemble simulations reveal skillful predictions of the environmental conditions several years in advance with distinct regional differences. In areas closely tied to large-scale climate variability and ice dynamics, both the physical and biogeochemical fields can be skillfully predicted more than 4 years ahead, while in areas under strong influence of upper oceans or open boundaries, the predictive skill for both fields is limited to a maximum of 2 years. The simulations suggest higher predictability for the biogeochemical fields than for the physical fields, which can be partly attributed to the longer persistence of the former fields. Predictability is improved by initialization in areas away from the influence of Mediterranean outflow and areas with weak coupling between the upper and deep oceans. Our study highlights the ability of the downscaling regional system to predict the environmental variations at deep-sea benthic habitats on time scales of management relevance. The downscaling system therefore will be an important part of an integrated approach towards the preservation and sustainable exploitation of the North Atlantic benthic habitats. %0 journal article %@ 2590-1621 %A Schwarzkopf, D., Petrik, R., Matthias, V., Quante, M., Majamäki, E., Jalkanen, J. %D 2021 %J Atmospheric Environment: X %P 100132 %R doi:10.1016/j.aeaoa.2021.100132 %T A ship emission modeling system with scenario capabilities %U https://doi.org/10.1016/j.aeaoa.2021.100132 %X A bottom-up modular ship emission modeling system (MoSES) is presented that calculates highly spatiotemporally resolved ship exhaust emissions, based on ship position data recorded from the automatic identification system. MoSES is built in a modularized architecture, which guarantees good expandability. Several ship-type specific methods have been developed for estimating missing ship characteristics that are important for ship emission modeling, such as the gross tonnage, main or auxiliary engine power, engine rating or the service speed, since these characteristics are often not available in present data. Additionally, most recent emission factors for sulfate and black carbon were derived from literature that cover formerly neglected low-sulfur fuels. MoSES is demonstrated by the creation of an emissions inventory for the North and Baltic Sea region, but it may readily be applied to other regions as well. The results were evaluated and compared to ship emission data calculated with the established Ship Traffic Assessment Model (STEAM 3). A good agreement with the daily shipping activity and CO2 emissions was found, although fewer emissions were calculated with MoSES for SO2, SO4 and NOX due to differences in the method for calculating the power consumption, the assumed fuel sulfur content, and applied emission factors. Furthermore, the impact of different emissions factors and uncertainties due to missing ship characteristics has been investigated. Additionally, extensive functionalities for scenario generation were implemented that allow the modification of a ship fleet in a model run. A filtering algorithm was developed to support scenario generation by the creation of sub-emission inventories. These contain only emissions of ships moving between two specific harbors or points of interest. This feature is demonstrated for the ship traffic between the five busiest harbors in the North Sea among each other, and between the English Channel. The scenario capability of the model is exemplified on a case based on sub-emission inventories, that investigates a decreased trade volume between representative ports of mainland Europe and the United Kingdom. %0 journal article %@ 0171-8630 %A van de Wolfshaar, K., Daewel, U., Hjøllo, S., Troost, T., Kreus, M., Pätsch, J., Ji, R., Maar, M. %D 2021 %J Marine Ecology Progress Series %P 79-95 %R doi:10.3354/meps13885 %T Sensitivity of the fish community to different prey fields and importance of spatial-seasonal patterns %U https://doi.org/10.3354/meps13885 %X Different fish species and life stages depend not only on food abundance, but also on the size of planktonic prey, and (mis-)matches in time and space with suitable prey may influence the growth and survival of fish during their lifetime. We explored the sensitivity of a fish community to spatial-temporal differences in plankton prey fields. Data from 5 different lower trophic level models in the North Sea (Delft3D-WAQ, ECOHAM, ECOSMO, HBM-ERGOM and NORWECOM) were used to force the food web model OSMOSE which simulates spatially and temporally explicit higher trophic level fish dynamics. The estimated fish biomass levels were clearly and positively linked to zooplankton biomass, and sensitivity studies varying zooplankton biomass revealed that spatial and temporal variation in zooplankton drives the differences in absolute fish biomass. More zooplankton size bins resulted in less fish biomass due to size-based foraging constraints (i.e. a smaller proportion of bins falls within the prey size range of a fish, resulting in a decrease in available food). Nevertheless, we found a consistent response across models in the relative biomass contribution and spatial patterns of selected fish groups, indicating low sensitivity of the composition of the simulated fish community to the zooplankton input. The robustness of the outcome will aid model acceptance and implementation into management action. Relative, not absolute, changes in primary and secondary production may therefore be used to study the effects of management scenarios on fish communities. %0 journal article %@ 0278-4343 %A Pein, J., Staneva, J., Daewel, U., Schrum, C. %D 2021 %J Continental Shelf Research %P 104582 %R doi:10.1016/j.csr.2021.104582 %T Channel curvature improves water quality and nutrient filtering in an artificially deepened mesotidal idealized estuary %U https://doi.org/10.1016/j.csr.2021.104582 %X Estuarine ecology suffers from both physical aspects of human influence, such as dredging, and biogeochemical aspects, such as eutrophication. Apart from being dredged, modern estuaries often manifest rectified geometries deprived of meanders or other nonlinear topographic features. This study has two overarching aims, a theoretical and a practical one. The theoretical objective is to establish an understanding of the effect of physical dynamics induced by channel meanders on the biogeochemical dynamics in a typical estuarine oxygen minimum zone. The practical aim is to clarify whether and how channel curvature can mitigate the consequences of human intervention, such as dredging and eutrophication. To answer these questions, a coupled hydrodynamic and water quality model is applied to a pair of idealized funnel-shaped topographies with dimensions and axial depth distribution similar to the Elbe Estuary, Germany, serving as the prototype estuary in this study. The first topography is symmetric about the channel axis (straight channel), while the second topography contains a small section of sinusoidal meanders in the dredged limnic reach of the estuary. The setups are forced by an M-2 tide and daily salinity and temperature data at the seaward open boundary. Atmospheric and river forcings are based on regional operational and observational data to impose seasonal temperature variability and biogeochemical cycles. The model simulates tidally driven estuarine physics, as well as seasonal estuarine cycles and axial gradients of nutrients, oxygen and plankton that characterize alluvial human-shaped and eutrophied estuaries. The channel meanders in the lower limnic reaches lead to locally enhanced ebb dominance, vertical overturning and increased levels of turbulent kinetic energy. The curvature-induced dynamics decrease turbidity levels by up to 12.5% and increase oxygen concentrations by up to 14% in the area of the oxygen minimum zone, improving the ecological status of the eutrophied estuary. Finally, we assess the sustainability of the ecological benefits of the channel meanders in the face of global warming by applying a simple 2 °C warming scenario to the straight and meandering channel cases. We demonstrate that channel meanders potentially improve estuarine ecology even under increased pressure due to climate change. %0 journal article %@ 0012-8252 %A Arlinghaus, P., Zhang, W., Wrede, A., Schrum, C., Neumann, A. %D 2021 %J Earth-Science Reviews %P 103803 %R doi:10.1016/j.earscirev.2021.103803 %T Impact of benthos on morphodynamics from a modeling perspective %U https://doi.org/10.1016/j.earscirev.2021.103803 %X Benthic organisms and their bioturbation activities have a profound effect on a multitude of sediment properties. While many studies have already explored benthic impacts at small temporal and spatial scales, little is known on how the small-scale effects accumulate and interactively guide large-scale (km-scale) morphological evolution. Here we firstly summarize the most important processes of benthos affecting sediment stability and then explore existing biomorphodynamic modeling studies both at small- and large-scales. In general, microbenthos (body size <0.1 mm) mainly stabilizes sediments while meio- (0.1–1 mm) and macrobenthos (>1 mm) may stabilize or destabilize sediments. Among all types of sediment, fine-grained fraction (silt and clay) is most sensitive to the impact of benthos. Benthic organisms have the capability to mediate sediment transport and sedimentation patterns beyond their habitats on the long-term and over a large-scale. However, so far, numerical models evaluating benthic impact are limited to explorative studies and have not reached a stage where they can be used for predictive modeling. The barriers hindering a further development of biomorphodynamic models include not only limited understanding of fundamental biological/bio-physical processes affecting morphological development and dynamic feedback loops among them but also a shortage of data for model calibration and confirmation of simulation results. On the other hand, thriving for higher model complexity does not necessarily lead to better performance. Before conducting biomorphodynamic modeling, researchers must figure out which questions can be answered in a meaningful sense with simulation results that can be compared with observations and which level of modeling complexity is sufficient for that purpose. %0 journal article %@ 0036-8075 %A Thiery, W., Lange, S., Rogelj, J., Schleussner, C.-F., Gudmundsson, L., Seneviratne, S.I., Andrijevic, M., Frieler, K., Emanuel, K., Geiger, T., Bresch, D.N., Zhao, F., Willner, S.N., Büchner, M., Volkholz, J., Bauer, N., Chang, J., Ciais, P., Dury, M., François, L., Grillakis, M., Gosling, S.N., Hanasaki, N., Hickler, T., Huber, V., Ito, A., Jägermeyr, J., Khabarov, N., Koutroulis, A., Liu, W., Lutz, W., Mengel, M., Müller, C., Ostberg, S., Reyer, C.P.O., Stacke, T., Wada, Y. %D 2021 %J Science %N 6564 %P 158-160 %R doi:10.1126/science.abi7339 %T Intergenerational inequities in exposure to climate extremes %U https://doi.org/10.1126/science.abi7339 6564 %X Under continued global warming, extreme events such as heat waves will continue to rise in frequency, intensity, duration, and spatial extent over the next decades (1–4). Younger generations are therefore expected to face more such events across their lifetimes compared with older generations. This raises important issues of solidarity and fairness across generations (5, 6) that have fueled a surge of climate protests led by young people in recent years and that underpin issues of intergenerational equity raised in recent climate litigation. However, the standard scientific paradigm is to assess climate change in discrete time windows or at discrete levels of warming (7), a “period” approach that inhibits quantification of how much more extreme events a particular generation will experience over its lifetime compared with another. By developing a “cohort” perspective to quantify changes in lifetime exposure to climate extremes and compare across generations (see the first figure), we estimate that children born in 2020 will experience a two- to sevenfold increase in extreme events, particularly heat waves, compared with people born in 1960, under current climate policy pledges. Our results highlight a severe threat to the safety of young generations and call for drastic emission reductions to safeguard their future. %0 journal article %@ 1755-876X %A Peneva, E., Stanev, E., Ciliberti, S., Lima, L., Aydogdu, A., Marinova, V., Valcheva, N. %D 2021 %J Journal of Operational Oceanography %N S1 %P 53-58 %R doi:10.1080/1755876X.2021.1946240 %T Interannual variations of the Black Sea Rim Current %U https://doi.org/10.1080/1755876X.2021.1946240 S1 %X Statement of the main outcome: The general circulation in the Black Sea features a cyclonic gyre encompassing the entire basin (Rim Current), which flows approximately over the continental slope, separating the coastal environment from the open sea. The speed of Rim Current varies from year to year giving an overall measure of the intensity of the circulation. The latter is important for many physical and biogeochemical processes such as the formation of the vertical stratification, replenishment of the Cold Intermediate Layer (CIL), dynamics of mesoscale eddies propagating along the gyre, biogeochemistry dynamics, heat redistribution within the basin, anchovy and other fish distribution, pollution dispersion. The data from satellite altimeters and physical modelling is used to identify the most representative areas where one can get stable estimates of the annual mean speed of the Rim Current for the period 1993–2019. An Ocean Monitoring Index, reflecting the annual state of the cyclonic circulation, referred as Black Sea Rim Current Index (BSRCI), is determined and its interannual variations are studied. The time-series of the BSRCI suggest that the Black Sea Rim current speed varies within ∼30% in the period 1993–2019 with positive trend of ∼0.1 m/s/decade. It is found that the Rim current is in close relation to the regional atmospheric circulation and the mean velocity variation is linked to the wind curl above the basin. This proves that the Sverdrup relation applies to the Black Sea Rim current. %0 journal article %@ 2049-9647 %A Kadow, C., Illing, S., Lucio-Eceiza, E., Bergemann, M., Ramadoss, M., Sommer, P., Kunst, O., Schartner, T., Pankatz, K., Grieger, J., Schuster, M., Richling, A., Thiemann, H., Kirchner, I., Rust, H., Ludwig, T., Cubasch, U., Ulbrich, U. %D 2021 %J Journal of Open Research Software %N 1 %P 13 %R doi:10.5334/jors.253 %T Introduction to Freva – A Free Evaluation System Framework for Earth System Modeling %U https://doi.org/10.5334/jors.253 1 %X Freva – Free Evaluation System Framework for Earth system modeling is an efficient solution to handle evaluation systems of research projects, institutes or universities in the climate community. It is a scientific software framework for high performance computing that provides all its available features both in a shell and web environment. The main system design is equipped with the programming interface, history of evaluations, and a standardized model database. Plugin – a generic application programming interface allows scientific developers to connect their analysis tools with the evaluation system independently of the programming language. History – the configuration sub-system stores every analysis performed with the evaluation system in a database. Databrowser – an implemented meta data system with its advanced but easy-to-handle search tool supports scientists and their plugins to retrieve the required information of the database. The combination of these three core components, increases the scientific outcome and enables transparency and reproducibility for research groups using Freva as their framework for evaluation of Earth system models. %0 journal article %@ 2045-2322 %A Wirtz, K. %D 2021 %J Scientific Reports %N 1 %P 13919 %R doi:10.1038/s41598-021-93248-y %T Changing readiness to mitigate SARS-CoV-2 steered long-term epidemic and social trajectories %U https://doi.org/10.1038/s41598-021-93248-y 1 %X Societal responses crucially shape the course of a pandemic, but are difficult to predict. Mitigation measures such as social distancing are here assumed to minimize a utility function that consists of two conflicting sub-targets, the disease related mortality and the multifaceted consequences of mitigation. The relative weight of the two sub-targets defines the mitigation readiness H, which entails the political, social, and psychological aspects of decision making. The dynamics of social and behavioral mitigation thus follows an adaptive rule, which in turn is mediated by a non-adaptive dynamics of H. This framework for social dynamics is integrated into an epidemiological model and applied to the ongoing SARS-CoV-2 pandemic. Unperturbed simulations accurately reproduce diverse epidemic and mitigation trajectories from 2020 to 2021, reported from 11 European countries, Iran, and 8 US states. High regional variability in the severity and duration of the spring lockdown and in peak mortality rates of the first SARS-CoV-2 wave can be explained by differences in the reconstructed readiness H. A ubiquitous temporal decrease of H has greatly intensified second and third waves and slowed down their decay. The unprecedented skill of the model suggests that the combination of an adaptive and a non-adaptive rule may constitute a more fundamental mode in social dynamics. Its implementation in an epidemic context can produce realistic long-term scenarios relevant for strategic planning, such as on the feasibility of a zero-infection target or on the evolutionary arms race between mutations of SARS-CoV-2 and social responses. %0 journal article %@ 2169-9275 %A Thewes, D., Stanev, E., Zielinski, O. %D 2021 %J Journal of Geophysical Research : Oceans %N 11 %P e2021JC017697 %R doi:10.1029/2021JC017697 %T The North Sea Light Climate: Analysis of Observations and Numerical Simulations %U https://doi.org/10.1029/2021JC017697 11 %X Recent studies have indicated changes in the light climate of the North Sea. An overall reduction of water clarity over the twentieth century could be observed in measurements, and more recent analysis suggests that these trends continue. Inorganic sediment is often named one of the driving factors in these changes and it has been shown to locally increase. With 20 years' worth of satellite-derived sediment data, we were able to conduct basin wide investigations of the temporal dynamics of the biogeochemical state of the North Sea. To identify the impact of inter-annual and seasonal changes in sediment, we fed from two different remote sensing sources (GlobColour & IFREMER) into a 3D coupled hydrodynamic and biological model. The light scheme in the Carbon Silicon Nitrogen Ecosystem model (CoSiNE) was modified to account for sediment specific attenuation. We performed a total of five numerical experiments for the period of 2000–2017. The main two experiments were conducted using monthly averaged data. Additionally, as controls, one experiment with annually averaged and one with a 20 years average of sediment, as well as a fifth one without sediment were performed. Our model showed a clear relation between changes in sediment and water clarity. Phytoplankton biomass was reduced only in areas with high nutrient availability. %0 journal article %@ 2299-3835 %A Danilovich, I., Geyer, B. %D 2021 %J Meteorology, Hydrology and Water Management %N 1-2 %R doi:10.26491/mhwm/139386 %T Estimates of current and future climate change in Belarus based on meteorological station data and the EURO-CORDEX-11 dataset %U https://doi.org/10.26491/mhwm/139386 1-2 %X This study provides an assessment of the current and future changes (in terms of both direction and value) in air temper-ature, precipitation, snow, wind and their extremes over the territory of Belarus using information from 42 meteorologi-cal stations and 92 regional circulation model (RCM) simulations with the highest available horizontal resolution (EUR-11). Three representative concentration pathway scenarios, namely, RCP2.6, RCP4.5 and RCP8.5, are considered. Results demonstrate that in recent decades, temperature has increased over the territory of Belarus by 1.3°C, with the largest increase occurring during the cold season (2.1-2.3°C). Ensemble scenarios project further increases in air tempera-ture in the current century by +0.5-1.5°C, +2.8°C, and +5.2°C under the RCP2.6, RCP4.5 and RCP8.5 scenarios, with the largest increase during the cold season under the RCP8.5 scenario. The annual means were observed to increase (in-significantly) by 5-7% and the summer precipitation extremes exhibited a 20-25% growth in recent decades. Moreover, dry conditions have intensified in Belarus, particularly during the growing season. Further increases in precipitation of 10-15% across Belarus are projected to occur in all seasons under the RCP4.5 and RCP8.5 scenarios. Simulation models predict greater increases in single day rainfall events compared to their multiday precipitation counterparts. The greatest increases in maximal dry period length (by 1-2) are expected to occur in summer and autumn. The models project the general decrease in snowfall across Belarus to continue into the current century, with a reduction in snow precipitation days of 10-30 days. Despite the reduced wind strength (by 0.9-1.0 m·s-1) since the 1970s over the territory of Belarus, the ensemble model reveals slight nonsignificant changes in seasonal and annual wind strengths until the end of the century. Significant changes of 1-3 days under varying directions of the wind regime were observed for days with a strong breeze and storms. %0 journal article %@ 0377-0265 %A von Storch, H., Zorita, E. %D 2021 %J Dynamics of Atmospheres and Oceans %P 101241 %R doi:10.1016/j.dynatmoce.2021.101241 %T Revisiting Hansen & Sutera’s suggestion of bimodality in the Northern Hemisphere midlatitude circulation %U https://doi.org/10.1016/j.dynatmoce.2021.101241 %X Our result has a dual significance, namely first for our understanding of atmospheric dynamics, and secondly of the ubiquitous temptations of the Zeitgeist. %0 journal article %@ 0899-8418 %A Spinoni, J., Barbosa, P., Bucchignani, E., Cassano, J., Cavazos, T., Cescatti, A., Christensen, J.H., Christensen, O.B., Coppola, E., Evans, J., Forzieri, G., Geyer, B., Giorgi, F., Jacob, D., Katzfey, J., Koenigk, T., Laprise, R., Lennard, C.J., Levent Kurnaz, M., Li, D., Llopart, M., McCormick, N., Naumann, G., Nikulin, G., Ozturk, T., Panitz, H.-J., da Rocha, R.P., Solman, S.A., Syktus, J., Tangang, F., Teichmann, C., Vautard, R., Vogt, J.V., Winger, K., Zittis, G., Dosio, A. %D 2021 %J International Journal of Climatology %N 15 %P 6825-6853 %R doi:10.1002/joc.7302 %T Global exposure of population and land-use to meteorological droughts under different warming levels and SSPs: A CORDEX-based study %U https://doi.org/10.1002/joc.7302 15 %X Global warming is likely to cause a progressive drought increase in some regions, but how population and natural resources will be affected is still underexplored. This study focuses on global population, forests, croplands and pastures exposure to meteorological drought hazard in the 21st century, expressed as frequency and severity of drought events. As input, we use a large ensemble of climate simulations from the Coordinated Regional Climate Downscaling Experiment (CORDEX), population projections from the NASA-SEDAC dataset and land-use projections from the Land-Use Harmonization 2 project for 1981–2100. The exposure to drought hazard is presented for five Shared Socioeconomic Pathways (SSP1-SSP5) at four Global Warming Levels (GWLs: 1.5°C to 4°C). Results show that considering only Standardized Precipitation Index (SPI; based on precipitation), the SSP3 at GWL4 projects the largest fraction of the global population (14%) to experience an increase in drought frequency and severity (versus 1981–2010), with this value increasing to 60% if temperature is considered (indirectly included in the Standardized Precipitation-Evapotranspiration Index, SPEI). With SPEI, considering the highest GWL for each SSP, 8 (for SSP2, SSP4, SSP5) and 11 (SSP3) billion people, that is, more than 90%, will be affected by at least one unprecedented drought. For SSP5 at GWL4, approximately 2 × 106 km2 of forests and croplands (respectively, 6% and 11%) and 1.5 × 106 km2 of pastures (19%) will be exposed to increased drought frequency and severity according to SPI, but for SPEI this extent will rise to 17 × 106 km2 of forests (49%), 6 × 106 km2 of pastures (78%) and 12 × 106 km2 of croplands (67%), being mid-latitudes the most affected. The projected likely increase of drought frequency and severity significantly increases population and land-use exposure to drought, even at low GWLs, thus extensive mitigation and adaptation efforts are needed to avoid the most severe impacts of climate change. %0 journal article %@ 1991-959X %A Sørland, S.L., Brogli, R., Pothapakula, P.K., Russo, E., Van De Walle, J., Ahrens, B., Anders, I., Bucchignani, E., Davin, E.L., Demory, M.-E., Dosio, A., Feldmann, H., Früh, B., Geyer, B., Keuler, K., Lee, D., Li, D., Van Lipzig, N.P.M., Min, S.-K., Panitz, H.-J., Rockel, B., Schär, C., Steger, C., Thiery, W. %D 2021 %J Geoscientific Model Development %N 8 %P 5125-5154 %R doi:10.5194/gmd-14-5125-2021 %T COSMO-CLM regional climate simulations in the Coordinated Regional Climate Downscaling Experiment (CORDEX) framework: a review %U https://doi.org/10.5194/gmd-14-5125-2021 8 %X In the last decade, the Climate Limited-area Modeling Community (CLM-Community) has contributed to the Coordinated Regional Climate Downscaling Experiment (CORDEX) with an extensive set of regional climate simulations. Using several versions of the COSMO-CLM-Community model, ERA-Interim reanalysis and eight global climate models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) were dynamically downscaled with horizontal grid spacings of 0.44∘ (∼ 50 km), 0.22∘ (∼ 25 km), and 0.11∘ (∼ 12 km) over the CORDEX domains Europe, South Asia, East Asia, Australasia, and Africa. This major effort resulted in 80 regional climate simulations publicly available through the Earth System Grid Federation (ESGF) web portals for use in impact studies and climate scenario assessments. Here we review the production of these simulations and assess their results in terms of mean near-surface temperature and precipitation to aid the future design of the COSMO-CLM model simulations. It is found that a domain-specific parameter tuning is beneficial, while increasing horizontal model resolution (from 50 to 25 or 12 km grid spacing) alone does not always improve the performance of the simulation. Moreover, the COSMO-CLM performance depends on the driving data. This is generally more important than the dependence on horizontal resolution, model version, and configuration. Our results emphasize the importance of performing regional climate projections in a coordinated way, where guidance from both the global (GCM) and regional (RCM) climate modeling communities is needed to increase the reliability of the GCM–RCM modeling chain. %0 journal article %@ 2190-4979 %A Weisse, R., Dailidiene, I., Hünicke, B., Kahma, K., Madsen, K., Omstedt, A., Parnell, K., Schöne, T., Soomere, T., Zhang, W., Zorita, E. %D 2021 %J Earth System Dynamics %N 3 %P 871-898 %R doi:10.5194/esd-12-871-2021 %T Sea level dynamics and coastal erosion in the Baltic Sea region %U https://doi.org/10.5194/esd-12-871-2021 3 %X There are a large number of geophysical processes affecting sea level dynamics and coastal erosion in the Baltic Sea region. These processes operate on a large range of spatial and temporal scales and are observed in many other coastal regions worldwide. This, along with the outstanding number of long data records, makes the Baltic Sea a unique laboratory for advancing our knowledge on interactions between processes steering sea level and erosion in a climate change context. Processes contributing to sea level dynamics and coastal erosion in the Baltic Sea include the still ongoing viscoelastic response of the Earth to the last deglaciation, contributions from global and North Atlantic mean sea level changes, or contributions from wind waves affecting erosion and sediment transport along the subsiding southern Baltic Sea coast. Other examples are storm surges, seiches, or meteotsunamis which primarily contribute to sea level extremes. Such processes have undergone considerable variation and change in the past. For example, over approximately the past 50 years, the Baltic absolute (geocentric) mean sea level has risen at a rate slightly larger than the global average. In the northern parts of the Baltic Sea, due to vertical land movements, relative mean sea level has decreased. Sea level extremes are strongly linked to variability and changes in large-scale atmospheric circulation. The patterns and mechanisms contributing to erosion and accretion strongly depend on hydrodynamic conditions and their variability. For large parts of the sedimentary shores of the Baltic Sea, the wave climate and the angle at which the waves approach the nearshore region are the dominant factors, and coastline changes are highly sensitive to even small variations in these driving forces. Consequently, processes contributing to Baltic sea level dynamics and coastline change are expected to vary and to change in the future, leaving their imprint on future Baltic sea level and coastline change and variability. Because of the large number of contributing processes, their relevance for understanding global figures, and the outstanding data availability, global sea level research and research on coastline changes may greatly benefit from research undertaken in the Baltic Sea. %0 journal article %@ 0014-0015 %A Di Cosmo, N., Wagner, S., Büntgen, U. %D 2021 %J Erdkunde : Archive for Scientific Geography %N 2 %P 87-104 %R doi:10.3112/erdkunde.2021.02.02 %T Climate and environmental context of the Mongol invasion of Syria and defeat at ‘Ayn Jālūt (1258–1260 CE) %U https://doi.org/10.3112/erdkunde.2021.02.02 2 %X After a successful conquest of large parts of Syria in 1258 and 1259 CE, the Mongol army lost the battle of 'Ayn Jālūt against Mamluks on September 3, 1260 CE. Recognized as a turning point in world history, their sudden defeat triggered the reconfiguration of strategic alliances and geopolitical power not only in the Middle East, but also across much of Eurasia. Despite decades of research, scholars have not yet reached consensus over the causes of the Mongol reverse. Here, we revisit previous arguments in light of climate and environmental changes in the aftermath of one the largest volcanic forcings in the past 2500 years, the Samalas eruption ~1257 CE. Regional tree ring-based climate reconstructions and state-of-the-art Earth System Model simulations reveal cooler and wetter conditions from spring 1258 to autumn 1259 CE for the eastern Mediterranean/Arabian region. We therefore hypothesize that the post-Samalas climate anomaly and associated environmental variability affected an estimated 120,000 Mongol soldiers and up to half a million of their horses during the conquest. More specifically, we argue that colder and wetter climates in 1258 and 1259 CE, while complicating and slowing the campaign in certain areas, such as the mountainous regions in the Caucasus and Anatolia, also facilitated the assault on Syria between January and March 1260. A return to warmer and dryer conditions in the summer of 1260 CE, however, likely reduced the regional carrying capacity and may therefore have forced a mass withdrawal of the Mongols from the region that contributed to the Mamluks’ victory. In pointing to a distinct environmental dependency of the Mongols, we offer a new explanation of their defeat at 'Ayn Jālūt, which effectively halted the further expansion of the largest ever land-based empire. %0 journal article %@ 0452-7739 %A Jensen, J., Ebener, A., Jänicke, L., Arns, A., Hubert, K., Wurpts, A., Berkenbrink, C., Weisse, R., Yi, X., Meyer, E. %D 2021 %J Die Küste %N 89 %P 131-142 %R doi:10.18171/1.089105 %T Untersuchungen zur Entwicklung der Tidedynamik an derdeutschen Nordseeküste (ALADYN) %U https://doi.org/10.18171/1.089105 89 %X Die deutsche Nordseeküste ist ein stark tidebeeinflusstes und komplexes Küstengewässer, das vielen natürlichen und anthropogenen Einwirkungen unterliegt. Diese Einwirkungen spiegeln sich in der Ausprägung der Gezeiten wider, die i. d. R. aus Pegelaufzeichnungen abgeleitet werden können. Das Verbundprojekt ALADYN („Analyse der beobachteten Tidedynamik in der Nordsee“, Förderkennzeichen: 03F0756 A-C) liefert einen Beitrag zur Erklärung der Änderungen und zeitlichen Variationen der Tidewasserstände und des Tidehubs seit Mitte des 20. Jahrhunderts. Untersucht wurden dazu mögliche groß- und kleinräumige Einflussfaktoren, die die Entwicklungen der Tidedynamik in der Deutschen Bucht beeinflusst haben. Zu den untersuchten großräumigen Einflussfaktoren zählen u. a. großräumige Veränderungen der Tidedynamik im Nordostatlantik, der Anstieg des mittle-ren Meeresspiegels, langfristige Schwankungen oder Veränderungen in der großräumigen atmosphärischen Zirkulation, überregionale morphologische Änderungen entlang der Küs-ten und der Einfluss größerer historischer Baumaßnahmen. Berücksichtigt wurden aber auch kleinräumige Einflüsse und lokale Maßnahmen im Bereich einzelner Pegel, wie z. B. größere Baumaßnahmen und die daraus resultierenden morphologischen Veränderungenim Küstenvorfeld. Um die beteiligten Prozesse zu identifizieren, wurde eine Abschätzung des Einflusses von lokalen Baumaßnahmen im Rahmen des Teilprojekts ALADYN-A durch das Forschungsinstitut Wasser und Umwelt (fwu) der Universität Siegen durchge-führt. Entwickelt wurde ein Ansatz zur Separierung großräumiger Entwicklungen von lo-kalen Effekten in langjährigen Beobachtungsdaten der Tidewasserstände und des Tidehubs. Mithilfe von Detailuntersuchungen der lokalen Effekte konnten Auswirkungen einzelner Baumaßnahmen beschrieben werden. Darüber hinaus wurden im Teilprojekt ALADYN-B die durchgeführten statistischen Analysen durch numerische Modelluntersu-chungen zum Einfluss großräumiger Effekte auf die Tidedynamik am Helmholtz-Zentrum Geesthacht (HZG) ergänzt. Zusätzlich untersuchte die Forschungsstelle Küste im Nieder-sächsischen Landesbetrieb für Wasserwirtschaft, Küsten- und Naturschutz (NLWKN) im Teilprojekt ALADYN-C Wechselwirkungen zwischen regionalen morphologischen Ver-änderungen in den Ästuaren und der Tidedynamik im angrenzenden Küstenvorfeld. An-hand der Gegenüberstellung verschiedener morphologischer Zustände konnte aufgezeigt werden, wie weit und wie stark die großräumige Tidedynamik durch regionale Veränderun-gen beeinflusst werden kann. %0 journal article %@ 1354-1013 %A Lacroix, F., Ilyina, T., Mathis, M., Laruelle, G., Regnier, P. %D 2021 %J Global Change Biology %N 21 %P 5491-5513 %R doi:10.1111/gcb.15822 %T Historical increases in land-derived nutrient inputs may alleviate effects of a changing physical climate on the oceanic carbon cycle %U https://doi.org/10.1111/gcb.15822 21 %X The implications of climate change and other human perturbations on the oceanic carbon cycle are still associated with large uncertainties. Global-scale modelling studies are essential to investigate anthropogenic perturbations of oceanic carbon fluxes but, until now, they have not considered the impacts of temporal changes in riverine and atmospheric inputs of P and N on the marine net biological productivity (NPP) and air–sea CO2 exchange (FCO2). To address this, we perform a series of simulations using an enhanced version of the global ocean biogeochemistry model HAMOCC to isolate effects arising from (1) increasing atmospheric CO2 levels, (2) a changing physical climate and (3) alterations in inputs of terrigenous P and N on marine carbon cycling over the 1905–2010 period. Our simulations reveal that our first-order approximation of increased terrigenous nutrient inputs causes an enhancement of 2.15 Pg C year−1 of the global marine NPP, a relative increase of +5% over the simulation period. This increase completely compensates the simulated NPP decrease as a result of increased upper ocean stratification of −3% in relative terms. The coastal ocean undergoes a global relative increase of 14% in NPP arising largely from increased riverine inputs, with regional increases exceeding 100%, for instance on the shelves of the Bay of Bengal. The imprint of enhanced terrigenous nutrient inputs is also simulated further offshore, inducing a 1.75 Pg C year−1 (+4%) enhancement of the NPP in the open ocean. This finding implies that the perturbation of carbon fluxes through coastal eutrophication may extend further offshore than that was previously assumed. While increased nutrient inputs are the largest driver of change for the CO2 uptake at the regional scale and enhance the global coastal ocean CO2 uptake by 0.02 Pg C year−1, they only marginally affect the FCO2 of the open ocean over our study's timeline. %0 journal article %@ 0094-8276 %A Steinert, N.J., González-Rouco, J.F., Melo Aguilar, C.A., García Pereira, F., García-Bustamante, E., de Vrese, P., Alexeev, V., Jungclaus, J.H., Lorenz, S.J., Hagemann, S. %D 2021 %J Geophysical Research Letters %N 20 %P e2021GL094273 %R doi:10.1029/2021GL094273 %T Agreement of Analytical and Simulation-Based Estimates of the Required Land Depth in Climate Models %U https://doi.org/10.1029/2021GL094273 20 %X Previous analytical and simulation-based analyses suggest that deeper land surface models are needed to realistically simulate the terrestrial thermal state in climate models, with implications for land-atmosphere interactions. Analytical approaches mainly focused on the subsurface propagation of harmonics such as the annual temperature signal, and a direct comparison with climate-change model output has been elusive. This study addresses the propagation of a harmonic pulse fitted to represent the timescale and amplitude of anthropogenic warming. Its comparison to land model simulations with stepwise increased bottom boundary depth leads to an agreement between the simulation-based and analytical frameworks for long-term climate trends. Any depth increase gradually decreases the relative error in the subsurface thermodynamics, and a minimum depth of 170 m is recommended to simulate the ground climate adequately. The approach provides an accurate estimate of the required land-model depth for climate-change simulations and assesses the relative bias in insufficiently deep land models. %0 journal article %@ 2296-6463 %A Chaikalis, S., Parinos, C., Möbius, J., Gogou, A., Velaoras, D., Hainbucher, D., Sofianos, S., Tanhua, T., Cardin, V., Proestakis, E., Amiridis, V., Androni, A., Karageorgis, A. %D 2021 %J Frontiers in Earth Science %P 614703 %R doi:10.3389/feart.2021.614703 %T Optical Properties and Biochemical Indices of Marine Particles in the Open Mediterranean Sea: The R/V Maria S. Merian Cruise, March 2018 %U https://doi.org/10.3389/feart.2021.614703 %X A rich data set on particulate matter optical properties and parameters (beam attenuation coefficient, volume concentration, particle size and PSD slope), accompanied by measurements of biochemical indices (particulate organic carbon, particulate nitrogen and their stable isotopic composition) was obtained from the surface to deep waters across the Mediterranean Sea, in March-April 2018. A decrease of beam attenuation coefficients, total particle volume concentrations, particulate organic carbon and nitrogen concentrations was noted towards the eastern Mediterranean Sea (EMed) in comparison to the western Mediterranean Sea (WMed). LISST-derived optical properties were significantly correlated with water mass characteristics. Overall, the most turbid water mass identified in the Mediterranean Sea was the Surface Atlantic water (AW), and the most transparent was the Transitional Mediterranean Water (TMW) in the Cretan Sea, whereas a general decrease in particulate matter concentration is observed from the WMed towards the EMed. Relatively depleted δ13C-POC values in the particle pool of the open Mediterranean Sea can be attributed to contribution from terrestrial inputs, mainly via atmospheric deposition. Throughout the entire water column, a significant positive correlation between particle beam attenuation coefficient and particulate organic carbon concentration is observed in the open Mediterranean Sea. Such relationship suggests the predominance of organic particles with biogenic origin. POC concentration and particle median diameter D50 are significantly and negatively correlated both in the WMed and the EMed Sea, confirming that small particles are POC-rich. At depth, a prominent decrease of most measured parameters was observed, with the exception of particle median diameter that increased substantially in the EMed towards the deep sea, suggesting potentially enhanced aggregation processes. The low particle size distribution slope ξ observed in the EMed, corresponding to larger particle populations, supports the above notion. Basin-wide Rayleigh-type isotopic fractionation in vertical profiles of δ15N-PN across the Mediterranean Sea, underlines the differences in the trophic characters of the two sub-basins and highlights the role of circulation changes on biogeochemical parameters and the redistribution of particulate matter as a source of nutrients in the water column. %0 journal article %@ 0277-3791 %A Lyu, Z., Goosse, H., Dalaiden, Q., Klein, F., Shi, F., Wagner, S., Braconnot, P. %D 2021 %J Quaternary Science Reviews %P 107205 %R doi:10.1016/j.quascirev.2021.107205 %T Spatial patterns of multi–centennial surface air temperature trends in Antarctica over 1–1000 CE: Insights from ice core records and modeling %U https://doi.org/10.1016/j.quascirev.2021.107205 %X The spatial pattern of Antarctic surface air temperature variability on multi–decadal to multi–centennial time scales is poorly known because of the short instrumental records, the relatively small number of high–resolution paleoclimate observations, and biases in climate models. Here, changes in surface air temperature over Antarctica are reconstructed over the past two millennia using data assimilation constrained by different ice core water isotope records in order to identify robust signals. The comparison between previous statistically based temperature reconstructions and simulations covering the full Common Era driven by natural and anthropogenic forcings shows major discrepancies occurring in the period 1–1000 CE over East Antarctica, with the reconstructions displaying a warming over 1–500 CE that is not reproduced by the simulations. This suggests that the trends in the first millennium deduced from the statistically based reconstructions are unlikely to be entirely forced by external forcings. Our reconstructions show the high sensitivity of the 500-year temperature trend in Antarctica and its spatial distribution to selection of the records for the reconstructions, especially during 1–500 CE. A robust cooling over Antarctica during 501–1000 CE has been obtained in three data assimilation–based reconstructions with a larger magnitude in the WAIS than elsewhere over Antarctica, in agreement with previous estimates with the larger changes than simulated in climate models. The reconstructions for atmospheric circulation indicate that the pattern of temperature changes over 501–1000 CE is related to the positive trend of Southern Annular Mode and a deepening of Amundsen Sea Low. This confirms the role of internal variability in the temperature trends on multi–centennial scales. %0 journal article %@ 1755-876X %A Benetazzo, A., Barbariol, F., Staneva, J., Davison, S., Ricchi, A., Behrens, A., Gayer, G., Pezzutto, P. %D 2021 %J Journal of Operational Oceanography %N sup1 %P 59-64 %R doi:10.1080/1755876X.2021.1946240 %T Copernicus Marine Service Ocean State Report, Issue 5 : Climatology and 2019 anomaly of maximum waves in the Mediterranean and Black Seas %U https://doi.org/10.1080/1755876X.2021.1946240 sup1 %X There is general consensus that high-quality predictions of extreme events during marine storms can substantially contribute to avoiding or minimising human and material damage, especially in busy waterways such as the Mediterranean and Black Seas. Reliable wave forecasts and hindcasts, together with long-term statistical analysis of extreme conditions, are then of utmost importance for monitoring marine areas. So far, however, the wave climate characterisation (average and anomaly relative to the average) has focused on the bulk characterisation of the significant wave height Hs, and it has lacked a description of the individual waves, such as the maximum ones that may occur at a given location in the sea. To fill this gap, in this section, we provide the intensity and geographical distribution of the maximum waves in the Mediterranean and Black Seas over 27 years (1993–2019), by representing the average annual (1993–2018) and anomaly for 2019 relative to the average of the 99th percentile of the expected maximum wave height Hm and crest height Cm. The analysis combines wave model hindcasts available through CMEMS model setup and the wave model WAVEWATCH III®, both forced with ECMWF ERA5 reanalysis winds. Results show that in 2019 maximum waves were smaller than usual in the Black Sea (anomalies of Hm up to −1.5 m), while in the Mediterranean Sea a markedly positive anomaly (+2.5 m for Hm) was found in the southern part of the basin. The peculiar 2019 configuration seems to be caused by a widespread atmospheric stability over the Black Sea and by depressions that rapidly passed over the Mediterranean Sea. %0 journal article %@ 1814-9324 %A Jonkers, L., Bothe, O., Kucera, M. %D 2021 %J Climate of the Past %N 6 %P 2577-2581 %R doi:10.5194/cp-17-2577-2021 %T Preface: Advances in paleoclimate data synthesis and analysis of associated uncertainty: towards data–model integration to understand the climate %U https://doi.org/10.5194/cp-17-2577-2021 6 %X No abstract %0 journal article %@ 1525-755X %A Steinert, N., González-Rouco, J., de Vrese, P., García-Bustamante, E., Hagemann, S., Melo-Aguilar, C., Jungclaus, J., Lorenz, S. %D 2021 %J Journal of Hydrometeorology %N 12 %P 3231-3254 %R doi:10.1175/JHM-D-21-0023.1 %T Increasing the Depth of a Land Surface Model. Part II: Temperature Sensitivity to Improved Subsurface Thermodynamics and Associated Permafrost Response %U https://doi.org/10.1175/JHM-D-21-0023.1 12 %X The impact of various modifications of the JSBACH land surface model to represent soil temperature and cold-region hydro-thermodynamic processes in climate projections of the twenty-first century is examined. We explore the sensitivity of JSBACH to changes in the soil thermodynamics, energy balance and storage, and the effect of including freezing and thawing processes. The changes involve 1) the net effect of an improved soil physical representation and 2) the sensitivity of our results to changed soil parameter values and their contribution to the simulation of soil temperatures and soil moisture, both aspects being presented in the frame of an increased bottom boundary depth from 9.83 to 1418.84 m. The implementation of water phase changes and supercooled water in the ground creates a coupling between the soil thermal and hydrological regimes through latent heat exchange. Momentous effects on subsurface temperature of up to ±3 K, together with soil drying in the high northern latitudes, can be found at regional scales when applying improved hydro-thermodynamic soil physics. The sensitivity of the model to different soil parameter datasets is relatively low but shows important implications for the root zone soil moisture content. The evolution of permafrost under preindustrial forcing conditions emerges in simulated trajectories of stable states that differ by 4–6 × 106 km2 and shows large differences in the spatial extent of 105–106 km2 by 2100, depending on the model configuration. %0 journal article %@ 1811-1602 %A Sherriff-Tadano, S., Klockmann, M. %D 2021 %J Past Global Changes Magazine %N 2 %P 84-85 %R doi:10.22498/pages.29.2.84 %T PMIP contributions to understanding the deep ocean circulation of the Last Glacial Maximum %U https://doi.org/10.22498/pages.29.2.84 2 %X Simulations of the Last Glacial Maximum (LGM) within PMIP significantly improved our understanding of the mechanisms that control the Atlantic Meridional Overturning Circulation (AMOC) in a glacial climate. Nonetheless, reproducing the reconstructed shallowing of the LGM AMOC remains a challenge for many models. %0 journal article %@ 1811-1602 %A Jungclaus, J., Bothe, O., Garcia-Bustamante, E., González-Rouco, J., Neukom, R., Schurer, A. %D 2021 %J Past Global Changes Magazine %N 2 %P 72-73 %R doi:10.22498/pages.29.2.72 %T Simulating the Common Era: The Past2K working group of PMIP %U https://doi.org/10.22498/pages.29.2.72 2 %X Simulations of Common Era climate evolution coordinated by PMIP's "Past2K" working group together with multi-proxy reconstructions from the PAGES 2k Network provide pivotal understanding for the evolution of the modern climate system and for expected changes in the near future. %0 journal article %@ 1525-755X %A González-Rouco, J., Steinert, N., García-Bustamante, E., Hagemann, S., de Vrese, P., Jungclaus, J., Lorenz, S., Melo-Aguilar, C., García-Pereira, F., Navarro, J. %D 2021 %J Journal of Hydrometeorology %N 12 %P 3211-3230 %R doi:10.1175/JHM-D-21-0024.1 %T Increasing the Depth of a Land Surface Model. Part I: Impacts on the Subsurface Thermal Regime and Energy Storage %U https://doi.org/10.1175/JHM-D-21-0024.1 12 %X The representation of the thermal and hydrological states in land surface models is important for a realistic simulation of land–atmosphere coupling processes. The available evidence indicates that the simulation of subsurface thermodynamics in Earth system models is inaccurate due to a zero-heat-flux bottom boundary condition being imposed too close to the surface. To assess the influence of soil model depth on the simulated terrestrial energy and subsurface thermal state, sensitivity experiments have been carried out in piControl, historical, and RCP scenarios. A deeper bottom boundary condition placement has been introduced into the JSBACH land surface model by enlarging the vertical stratification from 5 to 12 layers, thereby expanding its depth from 9.83 to 1416.84 m. The model takes several hundred years to reach an equilibrium state in stand-alone piControl simulations. A depth of 100 m is necessary, and 300 m recommendable, to handle the warming trends in historical and scenario simulations. Using a deep bottom boundary, warming of the soil column is reduced by 0.5 to 1.5 K in scenario simulations over most land areas, with the largest changes occurring in northern high latitudes, consistent with polar amplification. Energy storage is 3–5 times larger in the deep than in the shallow model and increases progressively with additional soil layers until the model depth reaches about 200 m. While the contents of Part I focus on the sensitivity of subsurface thermodynamics to enlarging the space for energy, Part II addresses the sensitivity to changing the space for water and improving hydrological and phase-change interactions. %0 journal article %@ 1814-9340 %A Bothe, O., Zorita, E. %D 2020 %J Climate of the Past %N 1 %P 341-369 %R doi:10.5194/cp-16-341-2020 %T Proxy surrogate reconstructions for Europe and the estimation of their uncertainties %U https://doi.org/10.5194/cp-16-341-2020 1 %X In general, our reconstruction agrees well at multi-decadal timescales with the Euro 2k reconstruction, which was conducted with two different statistical methods and no information from model simulations. In both methodological approaches, the decades around the year 1600 CE were the coldest. However, the approaches disagree on the warmest pre-industrial periods. The reconstructions from the analogue method also represent the local variations of the observed proxies. The diverse uncertainty estimates obtained from our analogue approaches can be locally larger or smaller than the estimates from the Euro 2k effort. Local uncertainties of the temperature reconstructions tend to be large in areas that are poorly covered by the proxy records. Uncertainties highlight the ambiguity of field-based reconstructions constrained by a limited set of proxies. %0 journal article %@ 1726-4170 %A Feurdean, A., Vannière, B., Finsinger, W., Warren, D., Connor, S. C., Forrest, M., Liakka, J., Panait, A., Werner, C., Andrič, M., Bobek, P., Carter, V. A., Davis, B., Diaconu, A.-C., Dietze, E., Feeser, I., Florescu, G., Gałka, M., Giesecke, T., Jahns, S., Jamrichová, E., Kajukało, K., Kaplan, J., Karpińska-Kołaczek, M., Kołaczek, P., Kuneš, P., Kupriyanov, D., Lamentowicz, M., Lemmen, C., Magyari, E. K., Marcisz, K., Marinova, E., Niamir, A., Novenko, E., Obremska, M., Pędziszewska, A., Pfeiffer, M., Poska, A., Rösch, M., Słowiński, M., Stančikaitė, M., Szal, M., Święta-Musznicka, J., Tanţău, I., Theuerkauf, M., Tonkov, S., Valkó, O., Vassiljev, J., Veski, S., Vincze, I., Wacnik, A., Wiethold, J., Hickler, T. %D 2020 %J Biogeosciences %N 5 %P 1213-1230 %R doi:10.5194/bg-17-1213-2020 %T Fire hazard modulation by long-term dynamics in land cover and dominant forest type in eastern and central Europe %U https://doi.org/10.5194/bg-17-1213-2020 5 %X Wildfire occurrence is influenced by climate, vegetation and human activities. A key challenge for understanding the risk of fires is quantifying the mediating effect of vegetation on fire regimes. Here, we explore the relative importance of Holocene land cover, land use, dominant functional forest type, and climate dynamics on biomass burning in temperate and boreo-nemoral regions of central and eastern Europe over the past 12 kyr. We used an extensive data set of Holocene pollen and sedimentary charcoal records, in combination with climate simulations and statistical modelling. Biomass burning was highest during the early Holocene and lowest during the mid-Holocene in all three ecoregions (Atlantic, continental and boreo-nemoral) but was more spatially variable over the past 3–4 kyr. Although climate explained a significant variance in biomass burning during the early Holocene, tree cover was consistently the highest predictor of past biomass burning over the past 8 kyr. In temperate forests, biomass burning was high at ∼45 % tree cover and decreased to a minimum at between 60 % and 70 % tree cover. In needleleaf-dominated forests, biomass burning was highest at ∼ 60 %–65 % tree cover and steeply declined at >65 % tree cover. Biomass burning also increased when arable lands and grasslands reached ∼ 15 %–20 %, although this relationship was variable depending on land use practice via ignition sources, fuel type and quantities. Higher tree cover reduced the amount of solar radiation reaching the forest floor and could provide moister, more wind-protected microclimates underneath canopies, thereby decreasing fuel flammability. Tree cover at which biomass burning increased appears to be driven by warmer and drier summer conditions during the early Holocene and by increasing human influence on land cover during the late Holocene. We suggest that long-term fire hazard may be effectively reduced through land cover management, given that land cover has controlled fire regimes under the dynamic climates of the Holocene. %0 journal article %@ 1680-7316 %A Bieser, J., Angot, H., Slemr, F., Martin, L. %D 2020 %J Atmospheric Chemistry and Physics %N 17 %P 10427-10439 %R doi:10.5194/acp-20-10427-2020 %T Atmospheric mercury in the Southern Hemisphere – Part 2: Source apportionment analysis at Cape Point station, South Africa %U https://doi.org/10.5194/acp-20-10427-2020 17 %X Further, we find that mercury concentrations and trends from long-range transport are independent of the source region (e.g. South America, Antarctica) and thus indistinguishable. Therefore, by filtering out air masses from source and sink regions we are able to create a dataset representing a southern hemispheric background Hg concentrations. Based on this dataset, we were able to show that the interannual variability in Hg concentrations at Cape Point is not driven by changes in atmospheric circulation but rather due to changes in global emissions (gold mining and biomass burning). %0 journal article %@ 2475-9066 %A Tejero-Cantero, A., Boelts, J., Deistler, M., Lueckmann, J., Durkan, C., Goncalves, P., Greenberg, D., Macke, J. %D 2020 %J The Journal of Open Source Software %N 52 %P 2505 %R doi:10.21105/joss.02505 %T sbi: A toolkit for simulation-based inference %U https://doi.org/10.21105/joss.02505 52 %X Scientists and engineers employ stochastic numerical simulators to model empirically observedphenomena. In contrast to purely statistical models, simulators express scientific principles thatprovide powerful inductive biases, improve generalization to new data or scenarios and allow forfewer, more interpretable and domain-relevant parameters. Despite these advantages, tuninga simulator’s parameters so that its outputs match data is challenging. Simulation-basedinference (SBI) seeks to identify parameter sets that a) are compatible with prior knowledgeand b) match empirical observations. Importantly, SBI does not seek to recover a single ‘best’data-compatible parameter set, but rather to identify all high probability regions of parameterspace that explain observed data, and thereby to quantify parameter uncertainty. In Bayesianterminology, SBI aims to retrieve the posterior distribution over the parameters of interest. Incontrast to conventional Bayesian inference, SBI is also applicable when one can run modelsimulations, but no formula or algorithm exists for evaluating the probability of data givenparameters, i.e. the likelihood.We presentsbi, a PyTorch-based package that implements SBI algorithms based on neu-ral networks.sbifacilitates inference on black-box simulators for practising scientists andengineers by providing a unified interface to state-of-the-art algorithms together with docu-mentation and tutorials. %0 journal article %@ 2296-7745 %A Xu, X., Lemmen, C., Wirtz, K. %D 2020 %J Frontiers in Marine Science %P 662 %R doi:10.3389/fmars.2020.00662 %T Less Nutrients but More Phytoplankton: Long-Term Ecosystem Dynamics of the Southern North Sea %U https://doi.org/10.3389/fmars.2020.00662 %X We here assess long-term trends in marine primary producers in the southern North Sea (SNS) with respect to ongoing regional Earth system changes. We applied a coupled high-resolution (1.5–4.5 km) 3d-physical-biogeochemical regional Earth System model that includes an advanced phytoplankton growth model and benthic biogeochemistry to hindcast ecosystem dynamics in the period 1961–2012. We analyzed the simulation together with in situ observations. Coinciding with the decreasing nutrient level at the beginning of the 1990s, we find a surprising increase in phytoplankton in the German Bight, but not in the more offshore parts of the SNS. We explain these complex patterns by a series of factors which are lacking in many state-of-the-art coupled ecosystem models such as changed light availability and physiological acclimation in phytoplankton. We also show that many coastal time-series stations in the SNS are located in small patches where our model predicts an opposite trend than found for the surrounding waters. Together, these findings call for a reconsideration of current modeling and monitoring schemes. %0 journal article %@ 1991-959X %A Eyring, V., Bock, L., Lauer, A., Righi, M., Schlund, M., Andela, B., Arnone, E., Bellprat, O., Carvalhais, N., Cionni, I., Cortesi, N., Crezee, B., Davin, E.L., Davini, P., Debeire, K., De Mora, L., Deser, C., Docquier, D., Earnshaw, P., Ehbrecht, C., Gier, B.K., Gonzalez-Reviriego, N., Goodman, P., Hagemann, S., Hardiman, S., Hassler, B., Hunter, A., Kadow, C., Kindermann, S., Koirala, S., Koldunov, N., Lejeune, Q., Lembo, V., Lovato, T., Lucarini, V., Müller, B., Pandde, A., Pérez-Zanón, N., Phillips, A., Predoi, V., Russell, J., Sellar, A., Stacke, T., Swaminathan, R., Von Hardenberg, J., Weigel, K., Zimmermann, K. %D 2020 %J Geoscientific Model Development %N 7 %P 3383-3438 %R doi:10.5194/gmd-13-3383-2020 %T Earth System Model Evaluation Tool (ESMValTool) v2.0 – an extended set of large-scale diagnostics for quasi-operational and comprehensive evaluation of Earth system models in CMIP %U https://doi.org/10.5194/gmd-13-3383-2020 7 %X The Earth System Model Evaluation Tool (ESMValTool) is a community diagnostics and performance metrics tool designed to improve comprehensive and routine evaluation of Earth system models (ESMs) participating in the Coupled Model Intercomparison Project (CMIP). It has undergone rapid development since the first release in 2016 and is now a well-tested tool that provides end-to-end provenance tracking to ensure reproducibility. It consists of (1) an easy-to-install, well-documented Python package providing the core functionalities (ESMValCore) that performs common preprocessing operations and (2) a diagnostic part that includes tailored diagnostics and performance metrics for specific scientific applications. Here we describe large-scale diagnostics of the second major release of the tool that supports the evaluation of ESMs participating in CMIP Phase 6 (CMIP6). ESMValTool v2.0 includes a large collection of diagnostics and performance metrics for atmospheric, oceanic, and terrestrial variables for the mean state, trends, and variability. ESMValTool v2.0 also successfully reproduces figures from the evaluation and projections chapters of the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) and incorporates updates from targeted analysis packages, such as the NCAR Climate Variability Diagnostics Package for the evaluation of modes of variability, the Thermodynamic Diagnostic Tool (TheDiaTo) to evaluate the energetics of the climate system, as well as parts of AutoAssess that contains a mix of top–down performance metrics. The tool has been fully integrated into the Earth System Grid Federation (ESGF) infrastructure at the Deutsches Klimarechenzentrum (DKRZ) to provide evaluation results from CMIP6 model simulations shortly after the output is published to the CMIP archive. A result browser has been implemented that enables advanced monitoring of the evaluation results by a broad user community at much faster timescales than what was possible in CMIP5. %0 journal article %@ 1561-8633 %A Teutsch, I., Weisse, R., Moeller, J., Krueger, O. %D 2020 %J Natural Hazards and Earth System Sciences %N 10 %P 2665-2680 %R doi:10.5194/nhess-20-2665-2020 %T A statistical analysis of rogue waves in the southern North Sea %U https://doi.org/10.5194/nhess-20-2665-2020 10 %X A new wave dataset from the southern North Sea covering the period 2011–2016 and composed of wave buoy and radar measurements sampling the sea surface height at frequencies between 1.28–4 Hz was quality controlled and scanned for the presence of rogue waves. Here rogue waves refer to waves whose height exceeds twice the significant wave height. Rogue wave frequencies were analysed, compared to Rayleigh and Forristall distributions, and spatial, seasonal and long-term variability was assessed. Rogue wave frequency appeared to be relatively constant over the course of the year and uncorrelated among the different measurement sites. While data from buoys basically correspond with expectations from the Forristall distribution, radar measurement showed some deviations in the upper tail pointing towards higher rogue wave frequencies. Number of data available in the upper tail is, however, still limited to allow a robust assessment. Some indications were found that the distribution of waves in samples with and without rogue waves were different in a statistical sense. However, differences were small and deemed not to be relevant as attempts to use them as a criterion for rogue wave detection were not successful in Monte Carlo experiments based on the available data. %0 journal article %@ 2169-9275 %A Pätsch, J., Gouretski, V., Hinrichs, I., Koul, V. %D 2020 %J Journal of Geophysical Research : Oceans %N 5 %P e2019JC015825 %R doi:10.1029/2019JC015825 %T Distinct Mechanisms Underlying Interannual to Decadal Variability of Observed Salinity and Nutrient Concentration in the Northern North Sea %U https://doi.org/10.1029/2019JC015825 5 %X The influence of large‐scale oceanic circulation on salinity in the northern North Sea has lead to the hypothesis that nutrient concentrations in this region are also driven by remote oceanic anomalies. Here, using a newly established biogeochemical data set of the North Sea, we show that interannual to decadal variability in winter nutrient concentrations exhibits distinct phase deviations from salinity. The variability in salinity is explained by zonal shifts in the position of the subpolar front (SPF) in the eastern North Atlantic and the associated advective delay. However, the high correlation and absence of advective delay between the position of the SPF and winter nutrient concentrations in the Shetland region (59–61°N, 1°W to 3°E) point to the role of atmospheric variability in driving concurrent changes in winter nutrient concentrations and the SPF position. Our analysis suggests that the prevailing wind direction and local distribution of winter nutrient concentrations together determine the interannual to decadal variability in winter nutrient concentrations in this region. In the analyzed observations, we find a strong spatial gradient in mean winter nutrient concentrations northwest of the Shetland region, which is absent in salinity. The horizontal shift of this spatial gradient, forced by changes in wind direction, has a larger influence on winter nutrient concentration in the Shetland region than the nutrient signal in oceanic anomalies originating from the eastern subpolar North Atlantic. Overall, we conclude that interannual to decadal variability in the observed nutrient concentrations is mainly driven by atmospheric variability here expressed as wind direction. %0 journal article %@ 1680-7316 %A Slemr, F., Martin, L., Labuschagne, C., Mkololo, T., Angot, H., Magand, O., Dommergue, A., Garat, P., Ramonet, M., Bieser, J. %D 2020 %J Atmospheric Chemistry and Physics %N 13 %P 7683-7692 %R doi:10.5194/acp-20-7683-2020 %T Atmospheric mercury in the Southern Hemisphere – Part 1: Trend and inter-annual variations in atmospheric mercury at Cape Point, South Africa, in 2007–2017, and on Amsterdam Island in 2012–2017 %U https://doi.org/10.5194/acp-20-7683-2020 13 %X The Minamata Convention on Mercury (Hg) entered into force in 2017, committing its 116 parties (as of January 2019) to curb anthropogenic emissions. Monitoring of atmospheric concentrations and trends is an important part of the effectiveness evaluation of the convention. A few years ago (in 2017) we reported an increasing trend in atmospheric Hg concentrations at the Cape Point Global Atmosphere Watch (GAW) station in South Africa (34.3535∘ S, 18.4897∘ E) for the 2007–2015 period. With 2 more years of measurements at Cape Point and the 2012–2017 data from Amsterdam Island (37.7983∘ S, 77.5378∘ E) in the remote southern Indian Ocean, a more complex picture emerges: at Cape Point the upward trend for the 2007–2017 period is still significant, but no trend or a slightly downward trend was detected for the period 2012–2017 at both Cape Point and Amsterdam Island. The upward trend at Cape Point is driven mainly by the Hg concentration minimum in 2009 and maxima in 2014 and 2012. Using ancillary data on 222Rn, CO, O3, CO2, and CH4 from Cape Point and Amsterdam Island, the possible reasons for the trend and its change are investigated. In a companion paper this analysis is extended for the Cape Point station by calculations of source and sink regions using backward-trajectory analysis. %0 journal article %@ 1944-9208 %A Merz, B., Kuhlicke, C., Kunz, M., Pittore, M., Babeyko, A., Bresch, D., Domeisen, D., Feser, F., Koszalka, I., Kreibich, H., Pantillon, F., Parolei, S., Pinto, J., Punge, H., Rivalta, E., Schröter, K., Strehlow, K., Weisse, R., Wurpts, A. %D 2020 %J Reviews of Geophysics %N 4 %P e2020RG000704 %R doi:10.1029/2020RG000704 %T Impact Forecasting to Support Emergency Management of Natural Hazards %U https://doi.org/10.1029/2020RG000704 4 %X Forecasting and early warning systems are important investments to protect lives, properties, and livelihood. While early warning systems are frequently used to predict the magnitude, location, and timing of potentially damaging events, these systems rarely provide impact estimates, such as the expected amount and distribution of physical damage, human consequences, disruption of services, or financial loss. Complementing early warning systems with impact forecasts has a twofold advantage: It would provide decision makers with richer information to take informed decisions about emergency measures and focus the attention of different disciplines on a common target. This would allow capitalizing on synergies between different disciplines and boosting the development of multihazard early warning systems. This review discusses the state of the art in impact forecasting for a wide range of natural hazards. We outline the added value of impact‐based warnings compared to hazard forecasting for the emergency phase, indicate challenges and pitfalls, and synthesize the review results across hazard types most relevant for Europe. %0 journal article %@ 1616-7341 %A Bonaduce, A., Staneva, J., Grayek, S., Bidlot, J., Breivik, O. %D 2020 %J Ocean Dynamics %P 1547-1569 %R doi:10.1007/s10236-020-01404-1 %T Sea-state contributions to sea-level variability in the European Seas %U https://doi.org/10.1007/s10236-020-01404-1 %X The contribution of sea-state-induced processes to sea-level variability is investigated through ocean-wave coupled simulations. These experiments are performed with a high-resolution configuration of the Geestacht COAstal model SysTem (GCOAST), implemented in the Northeast Atlantic, the North Sea and the Baltic Sea which are considered as connected basins. The GCOAST system accounts for wave-ocean interactions and the ocean circulation relies on the NEMO (Nucleus for European Modelling of the Ocean) ocean model, while ocean-wave simulations are performed using the spectral wave model WAM. The objective is to demonstrate the contribution of wave-induced processes to sea level at different temporal and spatial scales of variability. When comparing the ocean-wave coupled experiment with in situ data, a significant reduction of the errors (up to 40% in the North Sea) is observed, compared with the reference. Spectral analysis shows that the reduction of the errors is mainly due to an improved representation of sea-level variability at temporal scales up to 12 h. Investigating the representation of sea-level extremes in the experiments, significant contributions (> 20%) due to wave-induced processes are observed both over continental shelf areas and in the Atlantic, associated with different patterns of variability. Sensitivity experiments to the impact of the different wave-induced processes show a major impact of wave-modified surface stress over the shelf areas in the North Sea and in the Baltic Sea. In the Atlantic, the signature of wave-induced processes is driven by the interaction of wave-modified momentum flux and turbulent mixing, and it shows its impact to the occurrence of mesoscale features of the ocean circulation. Wave-induced energy fluxes also have a role (10%) in the modulation of surge at the shelf break. %0 journal article %@ 0930-7575 %A de Souza, M., Mathis, M., Mayer, B., Noernberg, M., Pohlmann, T. %D 2020 %J Climate Dynamics %P 651-664 %R doi:10.1007/s00382-020-05289-0 %T Possible impacts of anthropogenic climate change to the upwelling in the South Brazil Bight %U https://doi.org/10.1007/s00382-020-05289-0 %X Anthropogenic climate change is expected to strengthen upwelling events worldwide, driven by an increase of upwelling-favorable winds. However, Earth System Models (ESM) tend to underestimate regional processes due to their coarse grid resolution, which can lead to local biases. We use a high-resolution ocean model (1/12∘) forced by results from the Max-Planck-Institute-ESM to analyze the impact of the RCP8.5 emission scenario on the upwelling of South Atlantic Central Water (SACW) in the South Brazil Bight (SBB). We find a stronger Ekman forcing and a higher spread of SACW over the shelf, but this does not translate into higher vertical velocities at the bottom of the mixed-layer in the end of the century. The increased winds’ effect is essentially balanced by an increase in water column stability due to the surface warming. This is particularly important during austral summer, when this process tends to weaken the upwelling. Vertical velocities decrease significantly along the shelf break. Here, the upwelling regime is governed by the Brazil Current (BC) and slight changes in transport induce large responses in upwelling strength. The consequences are increased sea surface temperatures over most of the shelf, although mitigated by the SACW upwelling and kept below global projections. However, temperatures decrease along Cabo Frio. In this region, shelf break upwelling dominates and is enhanced by a local increase in the BC transport. This highlights the importance of regional processes and, more specifically, of changes in the BC transport for the upwelling in the SBB. %0 journal article %@ 2045-2322 %A Wirtz, K., Smith, S. %D 2020 %J Scientific Reports %P 1142 %R doi:10.1038/s41598-020-57890-2 %T Vertical migration by bulk phytoplankton sustains biodiversity and nutrient input to the surface ocean %U https://doi.org/10.1038/s41598-020-57890-2 %X Phytoplankton subsumes the great variety of unicellular photoautotrophs that perform roughly half of Earth’s primary production. They achieve this despite their challenging oceanic habitat, with opposing vertical gradients of nutrients (which often limit their growth near the surface) and light (which becomes limiting with increasing depth). Most phytoplankton species are commonly assumed to be incapable of moving actively between the zones of light and nutrient availability, which are separated vertically by from 30–120 m. Here we propose that a considerable fraction of phytoplankton vertically traverse these gradients over time scales from hours to weeks, employing variations of a common migration strategy to acquire multiple resources. We present a mechanistic Lagrangian model resolving phytoplankton growth linked to optimal migration behaviour and demonstrate unprecedented agreement of its calculated vertical CHL-a distributions with 773 profiles observed at five prominent marine time-series stations. Our simulations reveal that vertically cycling phytoplankton can pump up enough nutrient to sustain as much as half of oceanic Net Primary Production (NPP). Active locomotion is therefore a plausible mechanism enabling relatively high NPP in the oligotrophic surface ocean. Our simulations also predict similar fitness for a variety of very different migration strategies, which helps to explain the puzzling diversity of phytoplankton observed in the ocean. %0 journal article %@ 2073-4433 %A Li, D., Staneva, J., Grayek, S., Behrens, A., Feng, J., Yin, B. %D 2020 %J Atmosphere %N 3 %P 252 %R doi:10.3390/atmos11030252 %T Skill Assessment of an Atmosphere–Wave Regional Coupled Model over the East China Sea with a Focus on Typhoons %U https://doi.org/10.3390/atmos11030252 3 %X This study performed several sensitivity experiments to investigate the impact of atmosphere–wave coupling on the simulated wind and waves over the East China Sea (ECS) with a focus on typhoon events. These experiments include stand-alone regional atmosphere model (CCLM) simulations, stand-alone spectral wave model (WAM) simulations driven by the regional atmospheric model CCLM or ERA5 reanalysis, and two-way (CCLM-WAM) coupled simulations. We assessed the simulated wind speed and significant wave height against in situ observations and remote sensing data and focused on typhoon events in 2010. We analyzed the differences between the experiments in capturing the surface pressure, wind speed, and roughness length. Both ERA5 reanalysis data and our regional model simulations demonstrate high quality in capturing wind and wave conditions over the ECS. The results show that downscaled simulations tend to be closer to in situ observations than ERA5 reanalysis data in capturing wind variability and probability distribution, dominant wind and wave directions, strong typhoon intensity and related extreme significant wave height. In comparison with satellite observations, the CCLM-WAM simulation outperforms the CCLM in reducing wind bias. The coupled and uncoupled simulations are very similar in terms of other wind and wave statistics. Though there is much improvement in capturing typhoon intensity to ERA5, regional downscaled simulations still underestimate the wind intensity of tropical cyclones. View Full-Text %0 journal article %@ 0264-8172 %A Liang, C., Xie, X., He, Y., Chen, H., Yu, X., Zhang, W., Mi, H., Lu, B., Tian, D., Zhang, H., Li, M., Zhou, Z. %D 2020 %J Marine and Petroleum Geology %P 104161 %R doi:10.1016/j.marpetgeo.2019.104161 %T Multiple sediment sources and topographic changes controlled the depositional architecture of a palaeoslope-parallel canyon in the Qiongdongnan Basin, South China Sea %U https://doi.org/10.1016/j.marpetgeo.2019.104161 %X Submarine canyon deposits have drawn attention due to their significance on source-to-sink analysis and hydrocarbon exploration. High-resolution 2-D and 3-D seismic and exploration well data recently collected in the Ledong-Lingshui segment of the Qiongdongnan Basin are used to investigate the depositional architecture of the palaeoslope-parallel Central Canyon, which is distinct from other slope-perpendicular canyons. This study indicates that the canyon developed along the thalweg of a multiple stepped palaeotopography with a slope-parallel descending trend eastwards. The location of the thalweg is controlled by regional tectonics and progradational slope clinoforms in the western Qiongdongnan basin. Geographic changes in an extending direction and slope gradient of the palaeotopography resulted in variations in the depth and width of the canyon. Analysis of the canyon infillings indicates multiple sediment sources including an axial sediment source from the Central Vietnam and the western Hainan Island and a canyon-side source from the northern slope of the Qiongdongnan basin. Provenance study shows that the former source supplied relatively coarse-grained turbidites and the later supplied fine-grained mass transport deposits (MTD). Most of such MTDs originated from the northern slope of the basin. Evolution of the Central Canyon can be classified into three stages. Stage 1 is characterised by significant incisions that are responsible for the formation of the canyon. Subsequently or contemporaneously, the sharp bend at the beginning of the middle segment of the canyon likely resulted in lateral erosion, which triggered large-scale and small-scale canyon margin failures in the middle and lower segments of the canyon, respectively. The subsequent early filling stage (Stage 2) refers to the deposition of turbidites supplied by the axial sediment source. However, the morphology of the stepped thalweg slope resulted in sediment bypass in the upper segment of the Central Canyon. During the late filling stage (Stage 3), MTDs supplied by the canyon-side sediment source were dominated, and interbedded with turbidite deposits. The deposition of the MTDs resulted in the sharp decreases in canyon accommodation space and the abrupt southeastwards stepping of the deepest part of the canyon. Moreover, complex interactions between debris-flows and turbidity-flows occurred during this stage. Such variations in architecture of the canyon were controlled by multiple sediment supplies and topographic changes. The proposed conceptual model of canyon infilling and the resulting stratigraphic architecture could be applied in other analogous canyons for hydrocarbon exploration. %0 journal article %@ 0924-7963 %A Zhang, H., Liu, X., Wu, R., Chen, D., Zhang, D., Shang, X., Wang, Y., Song, X., Jin, W., Yu, L., Qi, Y., Tian, D., Zhang, W. %D 2020 %J Journal of Marine Systems %P 103345 %R doi:10.1016/j.jmarsys.2020.103345 %T Sea surface current response patterns to tropical cyclones %U https://doi.org/10.1016/j.jmarsys.2020.103345 %X Tropical cyclones (TCs) are strong synoptic systems which induce strong sea surface currents. This paper first cross-checks a detailed surface current response to specific TCs Rammasun (2014), Kalmaegi (2014) and Sarika (2016) based on buoy/mooring observations as well as a three-dimensional numerical model (three-dimensional version of the Price-Weller-Pinkel model, 3DPWP) and a one-dimensional semi-analytical model which simplifies the driving forcing into wind stress and Coriolis force, then estimates the impact of all possible tropical cyclones using the semi-analytical model. The results show that the sea surface current response to the kinetic energy input of TCs, which is dependent on the TC configurations (translation speed, size and intensity) and the environmental configurations (Coriolis frequency and upper ocean stratification), can be represented by two simple parameters, namely the TC nondimensional translation speed (S) and the TC wind force parameter () or TC wind energy parameter (). S represents a combined effect of TC translation speed, size and Coriolis frequency, determines the structure of surface current response. or represents a combined effect of TC intensity, mixed layer depth and Coriolis frequency, determines the intensity of surface current response or wind energy input into surface currents. Ekman-like divergence dominates the sea surface current response when S is small (0 < S ≤ 0.4), an inertial oscillation in the lee that bias to the right rear part of a TC dominates when S is medium (0.4 < S ≤ 5), and an impulse with forward (backward) current on the right (left) side of the track dominates when S is large (S > 5). The response pattern with S > 5 was rarely studied before. The three values range of S take up ~30.36%, ~69.36% and ~0.28% of all recorded TCs during 2001–2017, which explains why the second response pattern with 0.4 < S ≤ 5 is usually observed while the third response pattern with S > 5 has been rarely studied before. Besides, the surface rightward bias is greatest at S = 2.5 (S = 1.45) for current speed (kinetic energy input rate). () determine the amplitude of current speed (wind energy input into currents). This work provides a simple and easy-to-use method to estimate the surface current response pattern to TCs when TCs and associated environmental configurations are given, which may help to improve the parameterization of TCs in regional and climate modeling. It also suggests that S is a better index than TC translation speed to classify TCs when studying the oceanic response. %0 journal article %@ 0022-1694 %A Zhang, Y., Ren, J., Zhang, W. %D 2020 %J Journal of Hydrology %P 124908 %R doi:10.1016/j.jhydrol.2020.124908 %T Flocculation under the control of shear, concentration and stratification during tidal cycles %U https://doi.org/10.1016/j.jhydrol.2020.124908 %X Tide-dominated estuaries are often characterized by a high variability of turbulent shear, suspended particulate matter (SPM) concentration and salinity, which poses challenges for a comprehensive understanding of its mass transport including cohesive sediment dynamics. Here, a combined in situ and numerical study was undertaken to investigate the mechanism of flocculation during tidal cycles, with the aim to disentangle the impacts of turbulent shear, SPM concentration and salinity on flocs. Results show that microflocs (20–200 μm) dominate in the Pearl River Estuary and floc size variation is caused primarily by exchange between flocculi (4–20 μm) and microflocs. We also identified a critical shear rate (G* ≈ 5/s) below which floc exchange occurs slowly. Above the threshold, the particle size distribution is left-skewed and clustered below 60 μm. Evolutions of flocs with different initial sizes synchronize gradually to adapt to the local hydrological environment. The trends of floc size evolution and absolute net flocculation rates are similar among diverse tidal shear cycles. The reason can be attributed to the turbulent shear which enhances both aggregation and breakup processes, thereby limiting the floc size in a certain range. The higher the concentration, the larger both the particle size and the range of variation. In addition, results of numerical modelling reveal that the flocculation time for primary particles is inversely proportional to shear and concentration. A critical concentration (C* ≈ 50 mg/L), below which the impact of concentration on the equilibrium diameter of flocs is more than twice as strong as shear, whilst above which the equilibrium diameter is inversely proportional to the Kolmogorov microscale and weakly correlated to concentration, was also identified. Furthermore, halocline was found to increase vertical variation of flocs size, suggesting co-existence of different flocculation mechanisms across this layer. %0 journal article %@ 1367-9120 %A Zhang, W., Xiong, P., Meng, Q., Dudzinska-Nowak, J., Chen, H., Zhang, H., Zhou, F., Miluch, J., Harff, J. %D 2020 %J Journal of Asian Earth Sciences %P 104351 %R doi:10.1016/j.jseaes.2020.104351 %T Morphogenesis of a late Pleistocene delta off the south-western Hainan Island unraveled by numerical modeling %U https://doi.org/10.1016/j.jseaes.2020.104351 %X A paleo-river delta off the south-western (SW) Hainan Island has been identified based on seismic and core evidence. Dating results suggest its initial development in ~65 kyr BP during a global sea level lowstand (~85 m below modern level) and termination in ~56 kyr BP during a sea level highstand (~50 m below modern level). Analysis of the delta internal architecture indicated a dominant offshore transport pathway from the SW Hainan Island. In order to unravel possible driving mechanisms for morphogenesis of the delta, 3-Dimensional numerical modeling was applied to investigate oceanographic and morphodynamic scenarios corresponding to the initial delta development. Results indicate that sediment dynamics in the study area is controlled by a compound effect of monsoon-driven circulation, river plumes, tides and typhoons. Contribution of the Red River to the delta development is smaller than local rivers in SW Hainan due to a combined effect by regional circulation and tides which causes a detour of the buoyancy-driven plume around the delta, despite of its larger runoff and sediment discharge compared to those from the local rivers of Hainan. On the other hand, simulation results suggest at least ten-times higher sediment supply rate from SW Hainan during the developing phase of the river delta than the modern condition. Such enhanced sediment supply might be caused jointly by 1) increased local river runoff from SW Hainan, and 2) alongshore transport from eastern Hainan which was connected to the main land during the sea level lowstand. %0 journal article %@ 1616-7341 %A Stanev, E., Ricker, M. %D 2020 %J Ocean Dynamics %P 713-728 %R doi:10.1007/s10236-020-01348-6 %T Interactions between barotropic tides and mesoscale processes in deep ocean and shelf regions %U https://doi.org/10.1007/s10236-020-01348-6 %X The interactions between barotropic tides and mesoscale processes were studied using the results of a numerical model in which tidal forcing was turned on and off. The research area covered part of the East Atlantic Ocean, a steep continental slope, and the European Northwest Shelf. Tides affected the baroclinic fields at much smaller spatial scales than the barotropic tidal scales. Changes in the horizontal patterns of the M2 and M4 tidal constituents provided information about the two-way interactions between barotropic tides and mesoscale processes. The interaction between the atmosphere and ocean measured by the work done by wind was also affected by the barotropic tidal forcing. Tidal forcing intensified the transient processes and resulted in a substantial transformation of the wave number spectra in the transition areas from the deep ocean to the shelf. Tides flattened the sea-surface height spectra down to ~ k−2.5 power law, thus reflecting the large contribution of the processes in the high-frequency range compared to quasi-geostrophic motion. The spectra along sections parallel or normal to the continental slope differ from each other, which indicates that mesoscale turbulence was not isotropic. An analysis of the vorticity spectra showed that the flattening was mostly due to internal tides. Compared with the deep ocean, no substantial scale selectivity was observed on the shelf area. Particle tracking showed that the lengths of the Lagrangian trajectories increased by approximately 40% if the barotropic tidal forcing was activated, which contributed to changed mixing properties. The ratio between the horizontal and vertical scales of motion varied regionally depending on whether barotropic tidal forcing was included. The overall conclusion is that the barotropic tides affect substantially the diapycnal mixing. %0 journal article %@ 2072-4292 %A Chetan, M., Dornik, A., Ardelean, F., Georgievski, G., Hagemann, S., Romanovsky, V., Onaca, A., Drozdov, D. %D 2020 %J Remote Sensing %N 11 %P 1836 %R doi:10.3390/rs12111863 %T 35 Years of Vegetation and Lake Dynamics in the Pechora Catchment, Russian European Arctic %U https://doi.org/10.3390/rs12111863 11 %X High-latitude regions are a hot spot of global warming, but the scarce availability of observations often limits the investigation of climate change impacts over these regions. However, the utilization of satellite-based remote sensing data offers new possibilities for such investigations. In the present study, vegetation greening, vegetation moisture and lake distribution derived from medium-resolution satellite imagery were analyzed over the Pechora catchment for the last 35 years. Here, we considered the entire Pechora catchment and the Pechora Delta region, located in the northern part of European Russia, and we investigated the vegetation and lake dynamics over different permafrost zones and across the two major biomes, taiga, and tundra. We also evaluated climate data records from meteorological stations and re-analysis data to find relations between these dynamics and climatic behavior. Considering the Normalized Difference Vegetation Index (NDVI) and the Normalized Difference Moisture Index (NDMI) in the summer, we found a general greening and moistening of the vegetation. While vegetation greenness follows the evolution of summer air temperature with a delay of one year, the vegetation moisture dynamics seems to better concur with annual total precipitation rather than summer precipitation, and also with annual snow water equivalent without lag. Both NDVI and NDMI show a much higher variability across discontinuous permafrost terrain compared to other types. Moreover, the analyses yielded an overall decrease in the area of permanent lakes and a noticeable increase in the area of seasonal lakes. While the first might be related to permafrost thawing, the latter seems to be connected to an increase of annual snow water equivalent. The general consistency between the indices of vegetation greenness and moisture based on satellite imagery and the climate data highlights the efficacy and reliability of combining Landsat satellite data, ERA-Interim reanalysis and meteorological data to monitor temporal dynamics of the land surface in Arctic areas. %0 journal article %@ 0930-7575 %A de Vrese, P., Stacke, T. %D 2020 %J Climate Dynamics %P 1521-1537 %R doi:10.1007/s00382-020-05337-9 %T Irrigation and hydrometeorological extremes %U https://doi.org/10.1007/s00382-020-05337-9 %X In the present study, the Max-Planck-Institute for Meteorology’s Earth System Model is used to investigate irrigation’s general effect on severe and extreme hydrometeorological regimes. Our idealized simulations show a large potential to modulate the magnitude and occurrence frequency of severe and extreme precipitation rates, indicating the possibility to mitigate some of the detrimental effects of future climate change, but also a substantial risk due to the declining water availability in drying regions. Irrigation almost exclusively reduces the magnitude and occurrence frequency of severely and extremely dry conditions and has the potential to counter the drying trends that result from the 21st century increase in greenhouse gas concentrations—according to the RCP4.5 scenario. At the same time, irrigation does not only have a mitigating effect, as it increases the occurrence frequency and intensity of severely wet conditions in many regions. The study aims at irrigation’s theoretical (maximum) impact and investigates a highly idealized trajectory in which global irrigation is being maximized within hydrologically sustainable limits. However, even for this scenario, we find large regions in which present-day water extractions are not sustainable as they often rely on exhaustible sources. Especially, a depletion of non-renewable ground water in South Asia would lead to a strong reduction in irrigation and, consequently, a substantial increase in the occurrence frequency of severely and extremely dry months throughout the region. %0 journal article %@ 2073-4441 %A Daewel, U., Yakushev, E., Schrum, C., Nizetto, L., Mikheeva, E. %D 2020 %J Water %N 3 %P 817 %R doi:10.3390/w12030817 %T Understanding the Role of Organic Matter Cycling for the Spatio-Temporal Structure of PCBs in the North Sea %U https://doi.org/10.3390/w12030817 3 %X Using the North Sea as a case scenario, a combined three-dimensional hydrodynamic-biogeochemical-pollutant model was applied for simulating the seasonal variability of the distribution of hydrophobic chemical pollutants in a marine water body. The model was designed in a nested framework including a hydrodynamic block (Hamburg Shelf Ocean Model (HAMSOM)), a biogeochemical block (Oxygen Depletion Model (OxyDep)), and a pollutant-partitioning block (PolPar). Pollutants can be (1) transported via advection and turbulent diffusion, (2) get absorbed and released by a dynamic pool of particulate and dissolved organic matter, and (3) get degraded. Our model results indicate that the seasonality of biogeochemical processes, including production, sinking, and decay, favors the development of hot spots with particular high pollutant concentrations in intermediate waters of biologically highly active regions and seasons, and it potentially increases the exposure of feeding fish to these pollutants. In winter, however, thermal convection homogenizes the water column and destroys the vertical stratification of the pollutant. A significant fraction of the previously exported pollutants is then returned to the water surface and becomes available for exchange with the atmosphere, potentially turning the ocean into a secondary source for pollutants. Moreover, we could show that desorption from aging organic material in the upper aphotic zone is expected to retard pollutants transfer and burial into sediments; thus, it is considerably limiting the effectiveness of the biological pump for pollutant exports. %0 journal article %@ 1812-0784 %A Ricker, M., Stanev, E. %D 2020 %J Ocean Science %N 3 %P 637-655 %R doi:10.5194/os-16-637-2020 %T Circulation of the European northwest shelf: a Lagrangian perspective %U https://doi.org/10.5194/os-16-637-2020 3 %X The dynamics of the European northwest shelf (ENWS), the surrounding deep ocean, and the continental slope between them are analysed in a framework of numerical simulations using Lagrangian methods. Several sensitivity experiments are carried out in which (1) the tides are switched off, (2) the wind forcing is low-pass filtered, and (3) the wind forcing is switched off. To measure accumulation of neutrally buoyant particles, a quantity named the “normalised cumulative particle density (NCPD)” is introduced. Yearly averages of monthly results in the deep ocean show no permanent particle accumulation areas at the surface. On the shelf, elongated accumulation patterns persist in yearly averages, often occurring along the thermohaline fronts. In contrast, monthly accumulation patterns are highly variable in both regimes. Tides substantially affect the particle dynamics on the shelf and thus the positions of fronts. The contribution of wind variability to particle accumulation in specific regions is comparable to that of tides. The role of vertical velocities in the dynamics of Lagrangian particles is quantified for both the eddy-dominated deep ocean and for the shallow shelf. In the latter area, winds normal to coasts result in upwelling and downwelling, illustrating the importance of vertical dynamics in shelf seas. Clear patterns characterising the accumulation of Lagrangian particles are associated with the vertical circulations. %0 journal article %@ 0169-8095 %A Almagro, A., Oliveira, P., Rosolem, R., Hagemann, S., Nobre, C. %D 2020 %J Atmospheric Research %P 105053 %R doi:10.1016/j.atmosres.2020.105053 %T Performance evaluation of Eta/HadGEM2-ES and Eta/MIROC5 precipitation simulations over Brazil %U https://doi.org/10.1016/j.atmosres.2020.105053 %X Climate change effects can have significant impacts worldwide. Extreme events can modify water availability and agricultural production, making climate change planning an essential task. The National Institute for Space Research (INPE in Portuguese) in Brazil has made a large dataset of regional climate model outputs (simulations and projections) available, which opens up many possibilities of carrying out high-resolution climate change studies. However, there is still no performance evaluation of the model-derived rainfall output against high-resolution ground-based observation data considering the Brazilian biomes. This paper attempts to fill this gap and evaluates the simulated precipitation throughout Brazil. We used gridded observed precipitation data and historical climate simulations from the Model for Interdisciplinary Research on Climate, version 5 (MIROC5) and from the Hadley Center Global Environment Model, version 2 (HadGEM2-ES), which were downscaled by the Eta RCM (Regional Climate Model). For the overlapping period (1980–2005), there is good agreement (PBIAS up to 10%) of downscaled annual simulations for the Amazon and Cerrado biomes and large biases (reaching 40%) in the Pampa biome, compared to the observations. Our results showed that HadGEM2-ES is capable of representing long-term mean monthly precipitation for large areas well, such as the Amazon and Cerrado. Furthermore, the Eta RCM has considerably improved the driving GCM MIROC5 simulations. In conclusion, we recommend using the HadGEM2-ES simulations for the Amazon, Eta/HadGEM2-ES for the Atlantic Forest, Cerrado, and Pampa, and Eta/MIROC5 for the Caatinga and Pantanal. Our study provides an overview of two downscaled simulation datasets in Brazil that may help verify the models' suitability for further climate change assessments. %0 journal article %@ 1726-4170 %A Cohuo1, S., Macario-González, L., Wagner, S., Naumann, K., Echeverría-Galindo, P., Pérez, L., Curtis, J., Brenner, M., Schwalb, A. %D 2020 %J Biogeosciences %N 1 %P 145-161 %R doi:10.5194/bg-17-145-2020 %T Influence of late Quaternary climate on the biogeography of Neotropical aquatic species as reflected by non-marine ostracodes %U https://doi.org/10.5194/bg-17-145-2020 1 %X We evaluated how ranges of four endemic and non-endemic aquatic ostracode species changed in response to long-term (glacial–interglacial cycles) and abrupt climate fluctuations during the last 155 kyr in the northern Neotropical region. We employed two complementary approaches, fossil records and species distribution models (SDMs). Fossil assemblages were obtained from sediment cores PI-1, PI-2, PI-6 and Petén-Itzá 22-VIII-99 from the Petén Itzá Scientific Drilling Project, Lake Petén Itzá, Guatemala. To obtain a spatially resolved pattern of (past) species distribution, a downscaling cascade is employed. SDMs were reconstructed for the last interglacial (∼120 ka), the last glacial maximum (∼22 ka) and the middle Holocene (∼6 ka). During glacial and interglacial cycles and marine isotope stages (MISs), modelled paleo-distributions and paleo-records show the nearly continuous presence of endemic and non-endemic species in the region, suggesting negligible effects of long-term climate variations on aquatic niche stability. During periods of abrupt ecological disruption such as Heinrich Stadial 1 (HS1), endemic species were resilient, remaining within their current areas of distribution. Non-endemic species, however, proved to be more sensitive. Modelled paleo-distributions suggest that the geographic range of non-endemic species changed, moving southward into Central America. Due to the uncertainties involved in the downscaling from the global numerical to the highly resolved regional geospatial statistical modelling, results can be seen as a benchmark for future studies using similar approaches. Given relatively moderate temperature decreases in Lake Petén Itzá waters (∼5 ∘C) and the persistence of some aquatic ecosystems even during periods of severe drying in HS1, our data suggest (1) the existence of micro-refugia and/or (2) continuous interaction between central metapopulations and surrounding populations, enabling aquatic taxa to survive climate fluctuations in the northern Neotropical region. %0 journal article %@ 1099-1824 %A Cañadillas, B., Foreman, R., Barth, V., Siedersleben, S., Lampert, A., Platis, A., Djath, B., Schulz-Stellenfleth, J., Bange, J., Emeis, S., Neuman, T. %D 2020 %J Wind Energy %N 5 %P 1249-1265 %R doi:10.1002/we.2484 %T Offshore wind farm wake recovery: Airborne measurements and its representation in engineering models %U https://doi.org/10.1002/we.2484 5 %X We present an analysis of wind measurements from a series of airborne campaigns conducted to sample the wakes from two North Sea wind farm clusters, with the aim of determining the dependence of the downstream wind speed recovery on the atmospheric stability. The consequences of the stability dependence of wake length on the expected annual energy yield of wind farms in the North Sea are assessed by an engineering model. Wakes are found to extend for significantly longer downstream distances (>50 km) in stable conditions than in neutral and unstable conditions ( urn:x-wiley:we:media:we2484:we2484-math-0001 15 km). The parameters of one common engineering model are modified to reproduce the observed wake decay at downstream distances urn:x-wiley:we:media:we2484:we2484-math-0002 30 km. More significant effects on the energy yield are expected for wind farms separated by distances urn:x-wiley:we:media:we2484:we2484-math-0003 30 km, which is generally the case in the North Sea, but additional data would be required to validate the suggested parameter modifications within the engineering model. A case study is accordingly performed to show reductions in the farm efficiency downstream of a wind farm. These results emphasize not only the importance of understanding the impact of atmospheric stability on offshore wind farms but also the need to update the representation of wakes in current industry models to properly include wake‐induced energy losses, especially in large offshore clusters. %0 journal article %@ 1866-3508 %A Lampert, A., Bärfuss, K., Platis, A., Siedersleben, S., Djath, B., Cañadillas, B., Hunger, R., Hankers, R., Bitter, M., Feuerle, T., Schulz, H., Rausch, T., Angermann, M., Schwithal, A., Bange, J., Schulz-Stellenfleth, J., Neumann, T., Emeis, S. %D 2020 %J Earth System Science Data %N 2 %P 935-946 %R doi:10.5194/essd-12-935-2020 %T In situ airborne measurements of atmospheric and sea surface parameters related to offshore wind parks in the German Bight %U https://doi.org/10.5194/essd-12-935-2020 2 %X Between 6 September 2016 and 15 October 2017, meteorological measurement flights were conducted above the German Bight in the framework of the project WIPAFF (Wind Park Far Field). The scope of the measurements was to study long-range wakes with an extent larger than 10 km behind entire wind parks, and to investigate the interaction of wind parks and the marine atmospheric boundary layer. The research aircraft Dornier 128 of the Technische Universität (TU) Braunschweig performed in total 41 measurement flights during different seasons and different stability conditions. The instrumentation consisted of a nose boom with sensors for measuring the wind vector, temperature and humidity, and additionally sensors for characterizing the water surface, a surface temperature sensor, a laser scanner and two cameras in the visible and infrared wavelength range. A detailed overview of the aircraft, sensors, data post-processing and flight patterns is provided here. Further, averaged profiles of atmospheric parameters illustrate the range of conditions. The potential use of the data set has been shown already by first publications. The data are publicly available in the world data centre PANGAEA (https://doi.org/10.1594/PANGAEA.902845; Bärfuss et al., 2019a). %0 journal article %@ 1991-959X %A Siedersleben, S., Platis, A., Lundquist, J., Djath, B., Lampert, A., Bärfuss, K., Cañadillas, B., Schulz-Stellenfleth, J., Bange, J., Neumann, T., Emeis, S. %D 2020 %J Geoscientific Model Development %N 1 %P 249-268 %R doi:10.5194/gmd-13-249-2020 %T Turbulent kinetic energy over large offshore wind farms observed and simulated by the mesoscale model WRF (3.8.1) %U https://doi.org/10.5194/gmd-13-249-2020 1 %X Wind farms affect local weather and microclimates; hence, parameterizations of their effects have been developed for numerical weather prediction models. While most wind farm parameterizations (WFPs) include drag effects of wind farms, models differ on whether or not an additional turbulent kinetic energy (TKE) source should be included in these parameterizations to simulate the impact of wind farms on the boundary layer. Therefore, we use aircraft measurements above large offshore wind farms in stable conditions to evaluate WFP choices. Of the three case studies we examine, we find the simulated ambient background flow to agree with observations of temperature stratification and winds. This agreement allows us to explore the sensitivity of simulated wind farm effects with respect to modeling choices such as whether or not to include a TKE source, horizontal resolution, vertical resolution and advection of TKE. For a stably stratified marine atmospheric boundary layer (MABL), a TKE source and a horizontal resolution on the order of 5 km or finer are necessary to represent the impact of offshore wind farms on the MABL. Additionally, TKE advection results in excessively reduced TKE over the wind farms, which in turn causes an underestimation of the wind speed deficit above the wind farm. Furthermore, using fine vertical resolution increases the agreement of the simulated wind speed with satellite observations of surface wind speed. %0 journal article %@ %A Heath, M., Benkort, D., Brierly, A., Daewel, U., Hofmeister, R., Laverick, J., Proud, R., Speirs, D. %D 2020 %J Frontiers for Young Minds %P 103 %R doi:10.3389/frym.2020.00103 %T How Is Climate Change Affecting Marine Life in the Arctic? %U https://doi.org/10.3389/frym.2020.00103 %X Rising temperatures are melting the ice that covers the Arctic Ocean, allowing sunlight into waters that have been dark for thousands of years. Previously barren ice-covered regions are being transformed into productive seas. In this article, we explain how computer modeling can be used to predict how this transformation will affect the food web that connects plankton to fish and top predators, like whales and polar bears. Images of starving polar bears have become symbolic of the effects of the warming climate. Melting of the sea-ice is expected to reduce the bears’ ability to hunt for seals. However, at the same time, the food web upon which bears depend is becoming more productive, so it is not completely clear what the eventual outcome will be. Computer models help us to understand these systems and help us make policy decisions about the management of newly available Arctic resources. %0 journal article %@ 1561-8633 %A Grabemann, I., Gaslikova, L., Brodhagen, T., Rudolph, E. %D 2020 %J Natural Hazards and Earth System Sciences %N 7 %P 1985-2000 %R doi:10.5194/nhess-20-1985-2020 %T Extreme storm tides in the German Bight (North Sea) and their potential for amplification %U https://doi.org/10.5194/nhess-20-1985-2020 7 %X This study may serve as a first step towards an impact assessment for severe storm tides and towards implications for coastal zone management in times of climate change. %0 journal article %@ 2296-7745 %A Capet, A., Fernández, V., She, J., Dabrowski, T., Umgiesser, G., Staneva, J., Mészáros, L., Campuzano, F., Ursella, L., Nolan, G., El Serafy, G. %D 2020 %J Frontiers in Marine Science %P 129 %R doi:10.3389/fmars.2020.00129 %T Operational Modeling Capacity in European Seas—An EuroGOOS Perspective and Recommendations for Improvement %U https://doi.org/10.3389/fmars.2020.00129 %X An overview of the current European capacity in terms of operational modeling of marine and coastal systems is presented. This overview is compiled from a survey conducted in 2018–2019 among members of EuroGOOS and its related network of Regional Operational Oceanographic Systems, addressing the purposes, context and technical specificities of operational modeling systems. Contributions to the survey were received from 49 organizations around Europe, which represent 104 operational model systems simulating mostly hydrodynamics, biogeochemistry and sea waves. The analysis of contributions highlights the strengths and weaknesses of the current capacity from an operational point of view, and leads to the formulation of recommendations toward the improvement of marine operational modeling services in Europe. In particular, this study highlights the heterogeneity of the European operational modeling capacity in terms of atmospheric and land boundary conditions, its limited deployment for biogeochemical phenomena, and a restricted use of data assimilation methods. In order to improve the accuracy of their simulations, model operators aim toward a further refinement of spatial resolution, and identify the quality and accessibility of forcing data and the suitability of observations for data assimilation as restricting factors. The described issues call for institutional integration efforts and promotion of good practices to homogenize operational marine model implementations, and to ensure that external forcing datasets, observation networks and process formulations and parameterizations are adequately developed to enable the deployment of high-level operational marine and coastal modeling services across Europe. %0 journal article %@ 1436-3798 %A Jacob, D., Teichmann, C., Sobolowski, S., Katragkou, E., Anders, I., Belda, M., Benestad, R., Boberg, F., Buonomo, E., Cardoso, R.M., Casanueva, A., Christensen, O.B., Christensen, J.H., Coppola, E., De Cruz, L., Davin, E.L., Dobler, A., Domínguez, M., Fealy, R., Fernandez, J., Gaertner, M.A., García-Díez, M., Giorgi, F., Gobiet, A., Goergen, K., Gómez-Navarro, J.J., Alemán, J.J.G., Gutiérrez, C., Gutiérrez, J.M., Güttler, I., Haensler, A., Halenka, T., Jerez, S., Jiménez-Guerrero, P., Jones, R.G., Keuler, K., Kjellström, E., Knist, S., Kotlarski, S., Maraun, D., van Meijgaard, E., Mercogliano, P., Montávez, J.P., Navarra, A., Nikulin, G., de Noblet-Ducoudré, N., Panitz, H.-J., Pfeifer, S., Piazza, M., Pichelli, E., Pietikäinen, J.-P., Prein, A.F., Preuschmann, S., Rechid, D., Rockel, B., Romera, R., Sánchez, E., Sieck, K., Soares, P.M.M., Somot, S., Srnec, L., Sørland, S.L., Termonia, P., Truhetz, H., Vautard, R., Warrach-Sagi, K., Wulfmeyer, V. %D 2020 %J Regional Environmental Change %N 2 %P 51 %R doi:10.1007/s10113-020-01606-9 %T Regional climate downscaling over Europe: perspectives from the EURO-CORDEX community %U https://doi.org/10.1007/s10113-020-01606-9 2 %X The European CORDEX (EURO-CORDEX) initiative is a large voluntary effort that seeks to advance regional climate and Earth system science in Europe. As part of the World Climate Research Programme (WCRP) - Coordinated Regional Downscaling Experiment (CORDEX), it shares the broader goals of providing a model evaluation and climate projection framework and improving communication with both the General Circulation Model (GCM) and climate data user communities. EURO-CORDEX oversees the design and coordination of ongoing ensembles of regional climate projections of unprecedented size and resolution (0.11° EUR-11 and 0.44° EUR-44 domains). Additionally, the inclusion of empirical-statistical downscaling allows investigation of much larger multi-model ensembles. These complementary approaches provide a foundation for scientific studies within the climate research community and others. The value of the EURO-CORDEX ensemble is shown via numerous peer-reviewed studies and its use in the development of climate services. Evaluations of the EUR-44 and EUR-11 ensembles also show the benefits of higher resolution. However, significant challenges remain. To further advance scientific understanding, two flagship pilot studies (FPS) were initiated. The first investigates local-regional phenomena at convection-permitting scales over central Europe and the Mediterranean in collaboration with the Med-CORDEX community. The second investigates the impacts of land cover changes on European climate across spatial and temporal scales. Over the coming years, the EURO-CORDEX community looks forward to closer collaboration with other communities, new advances, supporting international initiatives such as the IPCC reports, and continuing to provide the basis for research on regional climate impacts and adaptation in Europe. %0 journal article %@ 1463-5003 %A Haid, V., Stanev, E., Pein, J., Staneva, J., Chen, W. %D 2020 %J Ocean Modelling %P 101585 %R doi:10.1016/j.ocemod.2020.101585 %T Secondary circulation in shallow ocean straits: Observations and numerical modeling of the Danish Straits %U https://doi.org/10.1016/j.ocemod.2020.101585 %X In this paper, we explore the secondary flows in the Danish Straits using observations and numerical simulations performed with the unstructured-grid hydrodynamic model SCHISM covering the North Sea and Baltic Sea. The straits are resolved on scales of up to 100 m. Given that large-scale atmospheric variability dominates the transport in these straits, we focus on the processes with subtidal time scales. Similarities and differences between the in- and outflows in the straits and flood and ebb flows in estuaries are analyzed. Contrary to the tidal straining in estuaries, the Danish Straits feature substantial differences in the stratification stability during the outflow and inflow phases. With a resolution of 100 m, new transport and mixing pathways that were previously unresolved appear fundamental to the strait dynamics. The variety of the strait morphology leads to high variability in the appearance of secondary circulation. Helical cells, often with a horizontal extension of 1 km, develop in the deep parts of the channels. A comparison between the high-resolution simulation and a simulation with a coarse grid of 500 m in the straits suggests that the coarser resolution overestimates the stratification and misrepresents the transport balance; the axial velocities and transport through the Sound are underestimated by 12%. These differences are explained by the missing secondary circulation when the coarse resolution is used (approximately two grid-points per cell instead of ten grid-points per cell in the fine resolution model), along with the resulting changes in mixing along the straits. In conclusion, the use of ultrafine resolution grids is essential to adequately resolve secondary flow patterns and two-layer exchange. Thus, the problems caused by the failure to resolve the secondary circulation in straits appear similar to the problems caused by the failure to resolve mesoscale eddies in ocean models. %0 journal article %@ 0894-8755 %A Spinoni, J., Barbosa, P., Bucchignani, E., Cassano, J., Cavazos, T., Christensen, J., Christensen, O., Coppola, E., Evans, J., Geyer, B., Giorgi, F., Hadjinicolaou, P., Jacob, D., Katzfey, J., Koenigk, T., Laprise, R., Lennard, C., Kurnatz, L., Li, D., Llopart, M., McCormick, N., Naumann, G., Nikulin, G., Ozturk, T., Panitz, H., da Rocha, R.P., Rockel, B., Solman, S., Syktus, J., Tangang, F., Teichmann, C., Vautard, R., Vogt, J., Winger, K., Zittis, G., Dosio, A. %D 2020 %J Journal of Climate %N 9 %P 3635-3661 %R doi:10.1175/JCLI-D-19-0084.1 %T Future Global Meteorological Drought Hot Spots: A Study Based on CORDEX Data %U https://doi.org/10.1175/JCLI-D-19-0084.1 9 %X Two questions motivated this study: 1) Will meteorological droughts become more frequent and severe during the twenty-first century? 2) Given the projected global temperature rise, to what extent does the inclusion of temperature (in addition to precipitation) in drought indicators play a role in future meteorological droughts? To answer, we analyzed the changes in drought frequency, severity, and historically undocumented extreme droughts over 1981–2100, using the standardized precipitation index (SPI; including precipitation only) and standardized precipitation-evapotranspiration index (SPEI; indirectly including temperature), and under two representative concentration pathways (RCP4.5 and RCP8.5). As input data, we employed 103 high-resolution (0.44°) simulations from the Coordinated Regional Climate Downscaling Experiment (CORDEX), based on a combination of 16 global circulation models (GCMs) and 20 regional circulation models (RCMs). This is the first study on global drought projections including RCMs based on such a large ensemble of RCMs. Based on precipitation only, ~15% of the global land is likely to experience more frequent and severe droughts during 2071–2100 versus 1981–2010 for both scenarios. This increase is larger (~47% under RCP4.5, ~49% under RCP8.5) when precipitation and temperature are used. Both SPI and SPEI project more frequent and severe droughts, especially under RCP8.5, over southern South America, the Mediterranean region, southern Africa, southeastern China, Japan, and southern Australia. A decrease in drought is projected for high latitudes in Northern Hemisphere and Southeast Asia. If temperature is included, drought characteristics are projected to increase over North America, Amazonia, central Europe and Asia, the Horn of Africa, India, and central Australia; if only precipitation is considered, they are found to decrease over those areas. %0 journal article %@ 2077-1312 %A Nam. P.T., Staneva, J., Thao, N.T., Larson, M. %D 2020 %J Journal of Marine Science and Engineering %N 2 %P 81 %R doi:10.3390/jmse8020081 %T Improved Calculation of Nonlinear Near-Bed Wave Orbital Velocity in Shallow Water: Validation against Laboratory and Field Data %U https://doi.org/10.3390/jmse8020081 2 %X A new parameterization for calculating the nonlinear near-bed wave orbital velocity in the shallow water was presented. The equations proposed by Isobe and Horikawa (1982) were modified in order to achieve more accurate predictions of the peak orbital velocities. Based on field data from Egmond Beach in the Netherlands, the correction coefficient and maximum skewness were determined as functions of the Ursell number. The obtained equations were validated against measurements from Egmond Beach, and with laboratory data from small-scale wave flume experiments at Delft University of Technology and from large-scale wave flume experiments at Delft Hydraulics. Inter-comparisons with other previously developed parameterizations were also carried out. The model simulations by the present study were in good agreement with the measurements and have been improved compared to the previous ones. For Egmond Beach, the root-mean-square errors for the peak onshore (uc) and offshore (ut) orbital velocities were approximately 21%. The relative biases were small, approximately 0.013 for uc and −0.068 for ut. The coefficient of determination was in the range between 0.64 and 0.68. For laboratory experiments, the root-mean-square errors in a range of 7.2%–24% for uc, and 7.9%–15% for ut. %0 journal article %@ 0924-7963 %A Butler, W., Guðmundsdóttir, L., Logemann, K., Langbehn, T., Marteinsdóttir, G. %D 2020 %J Journal of Marine Systems %P 103290 %R doi:10.1016/j.jmarsys.2019.103290 %T Egg size and density estimates for three gadoids in Icelandic waters and their implications for the vertical distribution of eggs along a stratified water column %U https://doi.org/10.1016/j.jmarsys.2019.103290 %X The vertical distribution of fish eggs can have important consequences for recruitment through its influence on dispersal trajectories and thus connectivity between spawning and nursery locations. Egg density and size are key parameters for the modelling of vertical egg distributions, both of which show variation at the species level, as well as between and within individuals (i.e., through ontogeny). We conducted laboratory experiments on the eggs of wild-spawning cod, haddock and saithe from Icelandic waters to estimate these parameters throughout ontogeny. Subsequently, this information was used in a 1-dimensional model to generate vertical distributions for each species along a stratified water column. Saithe eggs were significantly smaller and less dense than cod and haddock eggs. Cod eggs were slightly denser than haddock eggs in the first ontogenetic stage but statistically similar in the later stages. No significant differences were found between the egg diameters of cod and haddock. For each species, both parameters changed significantly through ontogeny. Yet despite these significant results, the 1-d model suggests that neither the interspecific nor ontogenetic differences would have a significant impact on the vertical egg distributions. Only under highly stratified conditions, when buoyancy is minimised due to the freshwater layer, do distributional differences become evident. In such situations, incorporating intraspecific variation in egg density into the model substantially reduced the distributional differences and this is highlighted as an important consideration for the modelling of pelagic vertical egg distributions. %0 journal article %@ 2045-2322 %A Koul, V., Tesdal, J., Bersch, M., Hatun, H., Brune, S., Borchert, L., Haak, H., Schrum, C., Baehr, J. %D 2020 %J Scientific Reports %P 1005 %R doi:10.1038/s41598-020-57790-5 %T Unraveling the choice of the north Atlantic subpolar gyre index %U https://doi.org/10.1038/s41598-020-57790-5 %X The north Atlantic subpolar gyre (SPG) has been widely implicated as the source of large-scale changes in the subpolar marine environment. However, inconsistencies between indices of SPG-strength have raised questions about the active role SPG-strength and size play in determining water properties in the eastern subpolar North Atlantic (ENA). Here, by analyzing various SPG indices derived from observations and a global coupled model, we show that the choice of the SPG index dictates the interpretation of SPG strength-salinity relationship in the ENA. Variability in geostrophic currents derived from observed hydrography and model based Lagrangian trajectories reveal zonal shifts of advective pathways in the ENA and meridional shifts in the western intergyre region. Such shifts in advective pathways are manifestations of variability in the size and strength of the SPG, and they impact salinity by modulating the proportion of subpolar and subtropical waters reaching the ENA. SPG indices based on subsurface density and principal component analysis of sea surface height variability capture these shifts in advective pathways, and are therefore best suited to describe SPG-salinity relationship in the ENA. Our results establish the dynamical constraints on the choice of the SPG index and emphasize that SPG indices should be cautiously interpreted. %0 journal article %@ 2073-4433 %A Ho-Hagemann, H., Hagemann, S., Grayek, S., Petrik, R., Rockel, B., Staneva, J., Feser, F., Schrum, C. %D 2020 %J Atmosphere %N 3 %P 227 %R doi:10.3390/atmos11030227 %T Internal Model Variability of the Regional Coupled System Model GCOAST-AHOI %U https://doi.org/10.3390/atmos11030227 3 %X Simulations of a Regional Climate Model (RCM) driven by identical lateral boundary conditions but initialized at different times exhibit the phenomenon of so-called internal model variability (or in short, Internal Variability—IV), which is defined as the inter-member spread between members in an ensemble of simulations. Our study investigates the effects of air-sea coupling on IV of the regional atmospheric model COSMO-CLM (CCLM) of the new regional coupled system model GCOAST-AHOI (Geesthacht Coupled cOAstal model SysTem: Atmosphere, Hydrology, Ocean and Sea Ice). We specifically address physical processes parameterized in CCLM, which may cause a large IV during an extreme event, and where this IV is affected by the air-sea coupling. Two six-member ensemble simulations were conducted with GCOAST-AHOI and the stand-alone CCLM (CCLM_ctr) for a period of 1 September–31 December 2013 over Europe. IV is expressed by spreads within the two sets of ensembles. Analyses focus on specific events during this period, especially on the storm Christian occurring from 27 to 29 October 2013 in northern Europe. Results show that simulations of CCLM_ctr vary largely amongst ensemble members during the storm. By analyzing two members of CCLM_ctr with opposite behaviors, we found that the large uncertainty in CCLM_ctr is caused by a combination of two factors (1) uncertainty in parameterization of cloud-radiation interaction in the atmospheric model. and (2) lack of an active two-way air-sea interaction. When CCLM is two-way coupled with the ocean model, the ensemble means of GCOAST-AHOI and CCLM_ctr are relatively similar, but the spread is reduced remarkably in GCOAST-AHOI, not only over the ocean where the coupling is done but also over land due to the land-sea interactions. %0 journal article %@ 0094-8276 %A Klockmann, M., Mikolajewicz, U., Kleppin, H., Marotzke, J. %D 2020 %J Geophysical Research Letters %N 21 %P e2020GL090361 %R doi:10.1029/2020GL090361 %T Coupling of the Subpolar Gyre and the Overturning Circulation During Abrupt Glacial Climate Transitions %U https://doi.org/10.1029/2020GL090361 21 %X We present a mechanism for self‐sustained ocean circulation changes that cause abrupt temperature changes over Greenland in a multi‐millennial climate model simulation with glacial CO2 concentrations representative of Marine Isotope Stage 3. The Atlantic meridional overturning circulation (AMOC) and the subpolar gyre (SPG) oscillate on millennial timescales. When the AMOC is strong, the SPG is weak and contracted; when the AMOC is weak, the SPG is strong and extensive. The coupling between the two systems via wind‐driven and density‐driven feedbacks is key to maintaining the oscillations. The SPG controls the transport of heat and salt into the deep‐water formation sites and thus controls the AMOC strength. The strength and location of the deep‐water formation affect the density‐driven part of the SPG and thus control the mean strength and extent of the SPG. This mechanism supports the hypothesis that coupled ocean‐ice‐atmosphere interactions could have triggered abrupt glacial climate change. %0 journal article %@ 2296-6463 %A Hagemann, S., Stacke, T., Ho-Hagemann, H.T.M. %D 2020 %J Frontiers in Earth Science %P 12 %R doi:10.3389/feart.2020.00012 %T High Resolution Discharge Simulations Over Europe and the Baltic Sea Catchment %U https://doi.org/10.3389/feart.2020.00012 %X Regional coupled system models require a high-resolution discharge component to couple their atmosphere/land components to the ocean component and to adequately resolve smaller catchments and the day-to-day variability of discharge. As the currently coupled discharge models usually do not fulfill this requirement, we improved a well-established discharge model, the Hydrological Discharge (HD) model, to be globally applicable at 5 Min. resolution. As the first coupled high-resolution discharge simulations are planned over Europe and the Baltic Sea catchment, we focus on the respective regions in the present study. As no river specific parameter adjustments were conducted and since the HD model parameters depend on globally available gridded characteristics, the model is, in principle, applicable for climate change studies and over ungauged catchments. For the validation of the 5 Min. HD (HD5) model, we force it with prescribed fields of surface and subsurface runoff. As no large-scale observations of these variables exist, they need to be calculated by a land surface scheme or hydrology model using observed or re-analyzed meteorological data. In order to pay regard to uncertainties introduced by these calculations, three different methods and datasets were used to derive the required fields of surface and subsurface runoff for the forcing of the HD5 model. However, the evaluation of the model performance itself is hampered by biases in these fields as they impose an upper limit on the accuracy of simulated discharge. 10-years simulations (2000-2009) show that for many European rivers, where daily discharge observations were available for comparison, the HD5 model captures the main discharge characteristics reasonably well. Deficiencies of the simulated discharge could often be traced back to deficits in the various forcing datasets. As direct anthropogenic impact on the discharge, such as by regulation or dams, is not regarded in the HD model, those effects can generally not be simulated. Thus, discharges for many heavily regulated rivers in Scandinavia or for the rivers Volga and Don are not well represented by the model. The comparison of the three sets of simulated discharges indicates that the HD5 model is suitable to evaluate the terrestrial hydrological cycle of climate models or land surface models, especially with regard to the separation of throughfall (rain or snow melt) into surface and subsurface runoff. %0 journal article %@ 2050-084X %A Gonçalves, P.J., Lueckmann, J.-M., Deistler, M., Nonnenmacher, M., Öcal, K., Bassetto, G., Chintaluri, C., Podlaski, W.F., Haddad, S.A., Vogels, T.P., Greenberg, D.S., Macke, J.H. %D 2020 %J eLife %P e56261 %R doi:10.7554/eLife.56261 %T Training deep neural density estimators to identify mechanistic models of neural dynamics %U https://doi.org/10.7554/eLife.56261 %X Mechanistic modeling in neuroscience aims to explain observed phenomena in terms of underlying causes. However, determining which model parameters agree with complex and stochastic neural data presents a significant challenge. We address this challenge with a machine learning tool which uses deep neural density estimators—trained using model simulations—to carry out Bayesian inference and retrieve the full space of parameters compatible with raw data or selected data features. Our method is scalable in parameters and data features and can rapidly analyze new data after initial training. We demonstrate the power and flexibility of our approach on receptive fields, ion channels, and Hodgkin–Huxley models. We also characterize the space of circuit configurations giving rise to rhythmic activity in the crustacean stomatogastric ganglion, and use these results to derive hypotheses for underlying compensation mechanisms. Our approach will help close the gap between data-driven and theory-driven models of neural dynamics. %0 journal article %@ 1027-5606 %A Do, H., Zhao, F., Westra, S., Leonard, M., Gudmundsson, L., Boulange, J., Chang, J., Ciais, P., Gerten, D., Gosling, S., Müller Schmied, H., Stacke, T., Telteu, C., Wada, Y. %D 2020 %J Hydrology and Earth System Sciences %N 3 %P 1543-1564 %R doi:10.5194/hess-24-1543-2020 %T Historical and future changes in global flood magnitude – evidence from a model–observation investigation %U https://doi.org/10.5194/hess-24-1543-2020 3 %X To improve the understanding of trends in extreme flows related to flood events at the global scale, historical and future changes of annual maxima of 7 d streamflow are investigated, using a comprehensive streamflow archive and six global hydrological models. The models' capacity to characterise trends in annual maxima of 7 d streamflow at the continental and global scale is evaluated across 3666 river gauge locations over the period from 1971 to 2005, focusing on four aspects of trends: (i) mean, (ii) standard deviation, (iii) percentage of locations showing significant trends and (iv) spatial pattern. Compared to observed trends, simulated trends driven by observed climate forcing generally have a higher mean, lower spread and a similar percentage of locations showing significant trends. Models show a low to moderate capacity to simulate spatial patterns of historical trends, with approximately only from 12 % to 25 % of the spatial variance of observed trends across all gauge stations accounted for by the simulations. Interestingly, there are statistically significant differences between trends simulated by global hydrological models (GHMs) forced with observational climate and by those forced by bias-corrected climate model output during the historical period, suggesting the important role of the stochastic natural (decadal, inter-annual) climate variability. Significant differences were found in simulated flood trends when averaged only at gauged locations compared to those averaged across all simulated grid cells, highlighting the potential for bias toward well-observed regions in our understanding of changes in floods. Future climate projections (simulated under the RCP2.6 and RCP6.0 greenhouse gas concentration scenarios) suggest a potentially high level of change in individual regions, with up to 35 % of cells showing a statistically significant trend (increase or decrease; at 10 % significance level) and greater changes indicated for the higher concentration pathway. Importantly, the observed streamflow database under-samples the percentage of locations consistently projected with increased flood hazards under the RCP6.0 greenhouse gas concentration scenario by more than an order of magnitude (0.9 % compared to 11.7 %). This finding indicates a highly uncertain future for both flood-prone communities and decision makers in the context of climate change. %0 journal article %@ 2169-8961 %A Meng, Q., Xuan, J., Zhang, W., Zhou, F., Hao, Q., Zhao, Q., Schrum, C. %D 2020 %J Journal of Geophysical Research : Biogeosciences %N 8 %P e2019JG005540 %R doi:10.1029/2019JG005540 %T Impact of Submesoscale Vertical Advection on Primary Productivity in the Southern East China Sea %U https://doi.org/10.1029/2019JG005540 8 %X This study aims to investigate the impact of submesoscale vertical advection (SVA) on the primary productivity in the southern East China Sea. The analysis is based on a comparison between two numerical simulations by using a three‐dimensional coupled physical‐biogeochemical model. One simulation directly resolves SVA on a high‐resolution mesh, and the other leaves SVA unresolved on a low‐resolution mesh. The high‐resolution simulation outperforms the low‐resolution simulation in reproducing the observed chlorophyll distribution, particularly in summer. Resolving SVA results in an approximately 40% increase in primary productivity during the summer, though SVA activity is relatively weak in this season than in other seasons. Among multiscale physical processes, SVA, rather than mixing, is found to be the most important vertical nutrient supply pathway from the nutrient‐rich bottom water to the nutrient‐depleted surface water in summer, particularly on the middle and outer shelves. The impact of SVA on the shelf is unique compared to the open ocean in that it efficiently enhances vertical supply of nutrient‐rich subsurface waters to the nutrient‐depleted surface layer. This study highlights the importance of SVA in promoting primary productivity in stratified shelf seas. %0 journal article %@ 2073-4433 %A Schreiberová, M., Vlasáková, L., Vlček, O., Šmejdířová, J., Horálek, J., Bieser, J. %D 2020 %J Atmosphere %N 9 %P 955 %R doi:10.3390/atmos11090955 %T Benzo[a]pyrene in the Ambient Air in the Czech Republic: Emission Sources, Current and Long-Term Monitoring Analysis and Human Exposure %U https://doi.org/10.3390/atmos11090955 9 %X This paper provides a detailed, thorough analysis of air pollution by benzo[a]pyrene (BaP) in the Czech Republic. The Czech residential sector is responsible for more than 98.8% of BaP, based on the national emission inventory. According to the data from 48 sites of the National Air Quality Monitoring Network, the range of annual average concentration of BaP ranges from 0.4 ng·m−3 at a rural regional station to 7.7 ng·m−3 at an industrial station. Additionally, short-term campaign measurements in small settlements have recorded high values of daily benzo[a]pyrene concentrations (0.1–13.6 ng·m−3) in winter months linked to local heating of household heating. The transboundary contribution to the annual average concentrations of BaP was estimated by the CAMx model to range from 46% to 70% over most of the country. However, the contribution of Czech sources can exceed 80% in residential heating hot spots. It is likely that the transboundary contribution to BaP concentrations was overestimated by a factor of 1.5 due to limitations of the modeling approach used. During the period of 2012–2018, 35–58% of the urban population in the Czech Republic were exposed to BaP concentrations above target. A significant decreasing trend, estimated by the Mann-Kendall test, was found for annual and winter BaP concentrations between 2008 and 2018. %0 journal article %@ 2072-4292 %A Ardelean, F., Onaca, A., Chetan, M., Dornik, A., Georgievski, G., Hagemann, S., Timofte, F., Berzescu, O. %D 2020 %J Remote Sensing %N 23 %P 3999 %R doi:10.3390/rs12233999 %T Assessment of Spatio-Temporal Landscape Changes from VHR Images in Three Different Permafrost Areas in the Western Russian Arctic %U https://doi.org/10.3390/rs12233999 23 %X Our study highlights the usefulness of very high resolution (VHR) images to detect various types of disturbances over permafrost areas using three example regions in different permafrost zones. The study focuses on detecting subtle changes in land cover classes, thermokarst water bodies, river dynamics, retrogressive thaw slumps (RTS) and infrastructure in the Yamal Peninsula, Urengoy and Pechora regions. Very high-resolution optical imagery (sub-meter) derived from WorldView, QuickBird and GeoEye in conjunction with declassified Corona images were involved in the analyses. The comparison of very high-resolution images acquired in 2003/2004 and 2016/2017 indicates a pronounced increase in the extent of tundra and a slight increase of land covered by water. The number of water bodies increased in all three regions, especially in discontinuous permafrost, where 14.86% of new lakes and ponds were initiated between 2003 and 2017. The analysis of the evolution of two river channels in Yamal and Urengoy indicates the dominance of erosion during the last two decades. An increase of both rivers’ lengths and a significant widening of the river channels were also observed. The number and total surface of RTS in the Yamal Peninsula strongly increased between 2004 and 2016. A mean annual headwall retreat rate of 1.86 m/year was calculated. Extensive networks of infrastructure occurred in the Yamal Peninsula in the last two decades, stimulating the initiation of new thermokarst features. The significant warming and seasonal variations of the hydrologic cycle, in particular, increased snow water equivalent acted in favor of deepening of the active layer; thus, an increasing number of thermokarst lake formations. %0 journal article %@ 2296-7745 %A Wiese, A., Staneva, J., Hagemann, H., Grayek, S., Koch, W., Schrum, C. %D 2020 %J Frontiers in Marine Science %P 596843 %R doi:10.3389/fmars.2020.596843 %T Internal Model Variability of Ensemble Simulations With a Regional Coupled Wave-Atmosphere Model GCOAST %U https://doi.org/10.3389/fmars.2020.596843 %X Ensemble simulations are performed to quantify the internal variability of both regional atmospheric models and wave-atmosphere coupled model systems. Studies have shown that the internal variability in atmospheric models (e.g., wind or pressure fields) is increased during extreme events, such as storms. Comparing the magnitude of the internal variability of the atmospheric model with the internal variability of the coupled model system reveals that the internal variability can be reduced by coupling a wave model to the atmospheric model. While this effect is most evident during extreme events, it is still present in a general assessment of the mean internal variability during the whole study period. Furthermore, the role of this wave-atmosphere coupling can be distinguished from that of the internal variability of the atmospheric model since the impact of the wave-atmosphere interaction is larger than the internal variability. This is shown to be robust to different boundary conditions. One method to reduce the internal variability of the atmospheric model is to apply spectral nudging, the role of which in both the stand-alone atmospheric model and the coupled wave-atmosphere system is evaluated. Our analyses show that spectral nudging in both coupled and stand-alone ensemble simulations keeps the internal variability low, while the impact of the wave-atmosphere interaction remains approximately the same as in simulations without spectral nudging, especially for the wind speed and significant wave height. This study shows that in operational and climate research systems, the internal variability of the atmospheric model is reduced when the ocean waves and atmosphere are coupled. Clear influences of the wave-atmosphere interaction on both of these earth system components can be detected and differentiated from the internal model variability. Furthermore, the wave-atmosphere coupling has a positive effect on the agreement of the model results with both satellite and in situ observations. %0 journal article %@ 0930-7575 %A Coppola, E., Sobolowski, S., Pichelli, E., Raffaele, F., Ahrens, B., Anders, I., Ban, N., Bastin, S., Belda, M., Belusic, D., Caldas-Alvarez, A., Cardoso, R.M., Davolio, S., Dobler, A., Fernandez, J., Fita, L., Fumiere, Q., Giorgi, F., Goergen, K., Guettler, I., Halenka, T., Heinzeller, D., Hodnebrog, Oe., Jacob, D., Kartsios, S., Katragkou, E., Kendon, E., Khodayar, S., Kunstmann, H., Knist, S., Lavin-Gullon, A., Lind, P., Lorenz, T., Maraun, D., Marelle, L., Meijgaard, E.van, Milovac, J., Myhre, G., Panitz, H.-J., Piazza, M., Raffa, M., Raub, T., Rockel, B., Schaer, C., Sieck, K., Soares, P.M.M., Somot, S., Srnec, L., Stocchi, P., Toelle, M.H., Truhetz, H., Vautard, R., de Vries, H., Warrach-Sagi, K. %D 2020 %J Climate Dynamics %P 3-34 %R doi:10.1007/s00382-018-4521-8 %T A first-of-its-kind multi-model convection permitting ensemble for investigating convective phenomena over Europe and the Mediterranean %U https://doi.org/10.1007/s00382-018-4521-8 %X A recently launched project under the auspices of the World Climate Research Program’s (WCRP) Coordinated Regional Downscaling Experiments Flagship Pilot Studies program (CORDEX-FPS) is presented. This initiative aims to build first-of-its-kind ensemble climate experiments of convection permitting models to investigate present and future convective processes and related extremes over Europe and the Mediterranean. In this manuscript the rationale, scientific aims and approaches are presented along with some preliminary results from the testing phase of the project. Three test cases were selected in order to obtain a first look at the ensemble performance. The test cases covered a summertime extreme precipitation event over Austria, a fall Foehn event over the Swiss Alps and an intensively documented fall event along the Mediterranean coast. The test cases were run in both “weather-like” (WL, initialized just before the event in question) and “climate” (CM, initialized 1 month before the event) modes. Ensembles of 18–21 members, representing six different modeling systems with different physics and modelling chain options, was generated for the test cases (27 modeling teams have committed to perform the longer climate simulations). Results indicate that, when run in WL mode, the ensemble captures all three events quite well with ensemble correlation skill scores of 0.67, 0.82 and 0.91. They suggest that the more the event is driven by large-scale conditions, the closer the agreement between the ensemble members. Even in climate mode the large-scale driven events over the Swiss Alps and the Mediterranean coasts are still captured (ensemble correlation skill scores of 0.90 and 0.62, respectively), but the inter-model spread increases as expected. In the case over Mediterranean the effects of local-scale interactions between flow and orography and land–ocean contrasts are readily apparent. However, there is a much larger, though not surprising, increase in the spread for the Austrian event, which was weakly forced by the large-scale flow. Though the ensemble correlation skill score is still quite high (0.80). The preliminary results illustrate both the promise and the challenges that convection permitting modeling faces and make a strong argument for an ensemble-based approach to investigating high impact convective processes. %0 journal article %@ 0308-597X %A Cormier, R., Londsdale, J. %D 2020 %J Marine Policy %P 103485 %R doi:10.1016/j.marpol.2019.02.056 %T Risk assessment for deep sea mining: An overview of risk %U https://doi.org/10.1016/j.marpol.2019.02.056 %X Deep-seabed mining is raising a variety of concerns regarding the effects of this activity on the marine environment, human health and safety, as well as socio-economic considerations. Risk management falls within a “management function” for developing, implementing and monitoring controls, and measures, as is the role of the International Seabed Authority, in contrast to a “governance function” for setting policies and direction as provided by UNCLOS. The risk assessment process is discussed for deep-seabed mining within the risk management process of ISO 31000 of identifying, analysing and evaluating risks. It highlights the importance of risk criteria in evaluating management options to reduce the risks of not achieving a policy objective such as avoiding harm to the marine environment. Administrative challenges and the need for policies and procedures are also discussed to effectively address transparency in such processes. %0 journal article %@ 1755-876X %A Ricker, M., Stanev, E., Badewien, H., Freund, H., Meyerjürgens, J., Wolff, J., Zielinski, O. %D 2020 %J Journal of Operational Oceanography - Copernicus Marine Service Ocean State Report, Issue 4 %N S1 %P S155-S160 %R doi:10.1080/1755876X.2020.1785097 %T Drifter observations and Lagrangian tracking of the 2018 easterly wind event in the North Sea %U https://doi.org/10.1080/1755876X.2020.1785097 S1 %X Persistent easterly winds in spring 2018 reversed the circulation in the North Sea for more than a month. This reversal has been documented by GPS-drifter observations, as well as by the stranding positions of wooden drifters released along the German North Sea coast. The latter information came from members of the public, the majority of which are likely to be non-scientists. It provided a valuable contribution to the GPS-drifter experiment and demonstrates an excellent example of the usefulness of citizen science. Lagrangian numerical experiments were also performed and helped explain and quantify the anomalous transport and the reversal of the circulation at the sea surface and in deeper layers. It has been shown that the CMEMS surface current products agree well with drifter observations, even under extreme wind conditions, which adds to their credibility. %0 journal article %@ 2296-7745 %A Thewes, D., Stanev, E., Zielinski, O. %D 2020 %J Frontiers in Marine Science %P 816 %R doi:10.3389/fmars.2019.00816 %T Sensitivity of a 3D Shelf Sea Ecosystem Model to Parameterizations of the Underwater Light Field %U https://doi.org/10.3389/fmars.2019.00816 %X The inherent optical properties of water in the North Sea vary widely in space and time. Their impact on the performance of a 3D-ecosystem-model of the North Sea needs to be critically evaluated, which is the major research issue in the present paper, specifically the horizontal variability of turbidity. We have performed a sensitivity analysis to a modification of a common approach of light treatment that is both valid for the North Sea, as well as computationally efficient to implement within a 3D-ecosystem-model. Using a coupled hydrodynamical model (Regional Ocean Modeling System, ROMS) and biological model (Carbon Silicate and Nitrogen Ecosystem model, CoSiNE), we found that simple changes to the original parameterization can yield significant improvements. ROMS-CoSiNE is shown to be suitable for use in a coupled ecosystem model of the North Sea. The model accurately reproduces the seasonal cycle of primary production in terms of timing and magnitude, while still being more affordable in comparison to full hyperspectral treatment or solving the radiative transfer equation. The modification introduces vertically increasing attenuation that is stronger in shallow domains, in a way that is similar to attenuation due to sediment. The resulting reduction of light availability leads to strongly reduced phytoplankton growth in shallow areas with high turbidity and weak nutrient limitation. Areas of depths between 50 and 100 m show greatest relative change with respect to their total ranges, while the deepest areas remain largely unchanged. We found that the consideration of spacial variability of light attenuation is necessary when modeling a heterogeneous domain, such as the North Sea. %0 journal article %@ 2169-9275 %A Meyerjürgens, J., Ricker, M., Schakau, V., Badewien, T., Stanev, E. %D 2020 %J Journal of Geophysical Research : Oceans %N 8 %P e2019JC015925 %R doi:10.1029/2019JC015925 %T Relative Dispersion of Surface Drifters in the North Sea: The Effect of Tides on Mesoscale Diffusivity %U https://doi.org/10.1029/2019JC015925 8 %X We examine the relative dispersion and the contribution of tides on the relative diffusivities of surface drifters in the North Sea. The drifters are released in two clusters, yielding 43 pairs, in the vicinity of a tidal mixing front in the German Bight, which is located in the southeastern area of the North Sea. Both clusters indicate decreasing dispersion when crossing the tidal mixing front, followed by exponentially increasing dispersion with e‐folding times of 0.5 days for Cluster 1 and 0.3 days for Cluster 2. A transition of the dispersion regimes is observed at scales of the order of the Rossby radius of deformation (10 km). After that, the relative dispersion grows with a power‐law dependency with a short period of ballistic dispersion (quadratic growth), followed by a Richardson regime (cubic growth) in the final phase. Scale‐dependent metrics such as the relative diffusivities are consistent with these findings, while the analysis of the finite‐scale Lyapunov exponents (FSLEs) shows contradictory results for the submesoscales. In summary, the analysis of various statistical Lagrangian metrics suggests that tracer stirring at the submesoscales is nonlocal and becomes local at separation scales larger than 10 km. The analysis of meridional and zonal dispersion components indicates anisotropic dispersion at the submesoscales, which changes into isotropic dispersion on the mesoscales. Spectral analysis of the relative diffusivity gives evidence that semidiurnal and shallow‐water tides influence relative diffusivity at the mesoscales, especially for drifter separations above 50 km. %0 journal article %@ 1467-3584 %A Njoroge, J.M., Ratter, B.M.W., Atieno, L., Mugabe, I.M. %D 2020 %J Tourism and Hospitality Research %N 1 %P 56-71 %R doi:10.1177/1467358418791353 %T Employing the enhanced Regional Tourism Sustainable Adaptation Framework with a case study of climate change vulnerability in Mombasa, Kenya %U https://doi.org/10.1177/1467358418791353 1 %X This paper attempts to provide an empirical application of the enhanced Regional Tourism Sustainable Adaptation Framework using a case study of Mombasa Kenya. Climate variability is a challenge to tourism destinations, especially coastal and Island destinations, categories under which Mombasa, our study site falls under. Mombasa has limited capacity to adapt to climate change considering its socio economic conditions and weak institutions, thus making it necessary to explore the possible sustainable pathways for the city using the enhanced Regional Tourism Sustainable Adaptation Framework. Earlier frameworks for tourism adaptation to climate change lacked focus on regional dynamics as well as sustainability aspects, and their implementation pose the risk of mal adaptation to some extent. Using secondary data and data from interviews with tourism stakeholders in Mombasa, the enhanced Regional Tourism Sustainable Adaptation Framework guides our assessment of vulnerability and resilience of the destination, as well as identification of region specific adaptation options for the city within the context of sustainable practice. Based on climate change perceived impacts, risks and vulnerability various adaptation options are presented and discussed as provided in literature. The usefulness of the framework in guiding regional tourism destination managers and policy makers in their pursuit for a regional adaptation options within the tourism sector in order to reduce destinations vulnerability, increase resilience and take advantage of opportunities presented by climate change is underscored. %0 journal article %@ 1616-7341 %A Saçu, S., Erdik, T., Stanev, E., Sen, O., Erdik, J., Öztürk, I. %D 2020 %J Ocean Dynamics %P 745-758 %R doi:10.1007/s10236-020-01358-4 %T Hydrodynamics of Canal Istanbul and its impact in the northern Sea of Marmara under extreme conditions %U https://doi.org/10.1007/s10236-020-01358-4 %X The Bosphorus, located at the junction of Asia and Europe, controls the transports of water, material, and energy between the Black Sea (BS) and the Mediterranean Sea. The Canal Istanbul (CI), planned by Republic of Turkey (TR), is a gigantic project which bisects the current European side of Istanbul, thus forming a secondary waterway parallel to the existing natural channel of the Bosphorus. The environmental impact of this project has been a major concern since the very beginning. To address this concern, a 3D hydrodynamic modeling study is carried out to investigate the impact of CI on the hydrodynamics and salinity of the northern Sea of Marmara (SM) by using the route and cross-section (CS) of canal, which was recently made public by the TR. An extensive set of model calibration is performed in a model where only the Bosphorus Strait links the Black Sea and Marmara Sea. Once the calibration process is completed, the future canal is added into the grid and new simulations are performed to analyze the influence of CI on hydrodynamics and salinities in the SM. It was found that the shallow water depth of CI is the limiting factor constraining the two-layer flow. Thus the vertical current structure of CI appears mostly as one-layer flow from the BS to the SM. One-layer flow from the SM toward the BS is rarely observed. In such cases, strong northerly storms caused water level setup at the SM and set down at the BS. Adding the CI in the model is responsible for a salinity decrease of ~1 ppt in the surface layer of SM. The salinity difference between the two models decreases gradually with the depth and it diminishes at the depth of 25 m. %0 journal article %@ 2073-4441 %A Tian, D., Zhang, H., Zhang, W., Zhou, F., Sun, X., Zhou, Y., Ke, D. %D 2020 %J Water %N 5 %P 1331 %R doi:10.3390/w12051331 %T Wave Glider Observations of Surface Waves During Three Tropical Cyclones in the South China Sea %U https://doi.org/10.3390/w12051331 5 %X Surface waves induced by tropical cyclones (TCs) play an important role in the air–sea interaction, yet are seldom observed. In the 2017 summer, a wave glider in the northern South China Sea successfully acquired the surface wave parameters when three TCs (Hato, Pakhar, and Mawar) passed though successively. During the three TCs, surface wave period increased from 4–6 s to ~8–10 s and surface wave height increased from 0–1 m to 3–8 m. The number of wave crests observed in a time interval of 1024 s decreased from 100–150 to 60–75. The sea surface roughness, a key factor in determining the momentum transfer between air and sea, increased rapidly during Hato, Pakhar, and Mawar. Surface waves rotated clockwise (anti-clockwise) on the right (left) side of the TC track, and generally propagated to the right side of the local cyclonic tangential direction relative to the TC center. The azimuthal dependence of the wave propagation direction is close to sinusoidal in a region within 50–600 km. The intersection angle between surface wave direction and the local cyclonic tangential direction is generally smallest in the right-rear quadrant of the TC and tends to be largest in the left-rear quadrant. This new set of glider wave observational data proves to be useful for assessing wave forecast products and for improvements in corresponding parameterization schemes. %0 journal article %@ 1994-0416 %A Essery, R., Kim, H., Wang, L., Bartlett, P., Boone, A., Brutel-Vuilmet, C., Burke, E., Cuntz, M., Decharme, B., Dutra, E., Fang, X., Gusev, Y., Hagemann, S., Haverd, V., Kontu, A., Krinner, G., Lafaysse, M., Lejeune, Y., Marke, T., Marks, D., Marty, C., Menard, C.B., Nasonova, O., Nitta, T., Pomeroy, J., Schädler, G., Semenov, V., Smirnova, T., Swenson, S., Turkov, D., Wever, N., Yuan, H. %D 2020 %J The Cryosphere %N 12 %P 4687-4698 %R doi:10.5194/tc-14-4687-2020 %T Snow cover duration trends observed at sites and predicted by multiple models %U https://doi.org/10.5194/tc-14-4687-2020 12 %X The 30-year simulations of seasonal snow cover in 22 physically based models driven with bias-corrected meteorological reanalyses are examined at four sites with long records of snow observations. Annual snow cover durations differ widely between models, but interannual variations are strongly correlated because of the common driving data. No significant trends are observed in starting dates for seasonal snow cover, but there are significant trends towards snow cover ending earlier at two of the sites in observations and most of the models. A simplified model with just two parameters controlling solar radiation and sensible heat contributions to snowmelt spans the ranges of snow cover durations and trends. This model predicts that sites where snow persists beyond annual peaks in solar radiation and air temperature will experience rapid decreases in snow cover duration with warming as snow begins to melt earlier and at times of year with more energy available for melting. %0 journal article %@ 1573-160X %A Stanev, E., Ricker, M., Grayek, S., Jacob, B., Haid, V., Staneva, J. %D 2020 %J Physical Oceanography %N 6 %P 631-658 %R doi:10.22449/1573-160X-2020-6-631-658 %T Numerical eddy-resolving modeling of the ocean: Mesoscale and sub-mesoscale examples %U https://doi.org/10.22449/1573-160X-2020-6-631-658 6 %X Conclusions. Without proper resolution, the models of tidal oceanic dynamics simulate the ocean general circulation, but do not describe correctly the energy cascades at the eddy scales including interaction between the tides and the mesoscale eddies. Absence of this sub-mesoscale dynamics in the models can largely affect their capability to simulate the two-layer inter-basin exchange. %0 journal article %@ 1367-9120 %A Xiong, P., Dudzinska-Nowak, J., Harff, J., Xie, X., Zhang, W., Chen, H., Jakub, M., Feldens, P., Macig, F., Osadczuk, A., Meng, Q., Zorita, E. %D 2020 %J Journal of Asian Earth Sciences %P 104542 %R doi:10.1016/j.jseaes.2020.104542 %T Modeling paleogeographic scenarios of the last glacial cycle as a base for source-to-sink studies: An example from the northwestern shelf of the South China Sea %U https://doi.org/10.1016/j.jseaes.2020.104542 %X Sea-level (SL) data from the Last Glacial Cycle (LGC) have been superimposed on to digital elevation models of the South China Sea (SCS) and adjacent areas, to generate regional paleogeographic scenarios related to 4th- to 5th-order Milankovitch climate cycles. These scenarios—at 123, 65, 60.5, 56, 20, and 0.5 kyr BP—showed that the SCS functioned as an oceanographic interface between the Pacific and Indian oceans during the LGC. A Late Pleistocene paleo-river delta (Hainan delta) offshore west of Hainan Island (China) was an important sediment routing system on the NW shelf of the SCS. To understand the origin of the Hainan delta better, paleo-reliefs of DEM56kyrBP and DEM65kyrBP were reconstructed, using seismic stratigraphy, sedimentology, and back-stripping methods. Geostatistical and geometric models of clinoforms and delta geometry, as well as the courses of the reconstructed paleo-distributary channels and paleo-river valleys, supported the interpretation that most delta sediment could be regarded as erosional products from Hainan Island. We hypothesized that an intensification of sediment supply outpaced SL rise during the Marine Isotopic Stages 4/3 transition, resulting in a normal regression during the formation of the Hainan delta. Morphodynamic modeling and meteorological data reanalysis further supported our interpretation that shifts in the Asian Monsoon system—combined with local meteorological effects on Hainan Island and with global SL changes—were the main drivers for the sediment source-to-sink systems at the NW SCS continental margin, during the LGC. %0 journal article %@ 1674-487X %A Chen, H., Xie, X., Mao, K., He, Y., Su, M., Zhang, W. %D 2020 %J Journal of Earth Science %N 4 %P 808-819 %R doi:10.1007/s12583-020-1284-z %T Depositional Characteristics and Formation Mechanisms of Deep-Water Canyon Systems along the Northern South China Sea Margin %U https://doi.org/10.1007/s12583-020-1284-z 4 %X Submarine canyon systems are sites for coarser clastic sediment accumulations in the deep-water domains, having the most potential for hydrocarbon reservoirs. Based on the interpretation of high resolution 2D/3D seismic and drilling data, depositional characteristics of three large deep-water canyon systems on the South China Sea northern margin have been analyzed. The Central Canyon System has a deep incision geomorphology extending from east to west, featured by distinct canyon segmentations, multi-provenance sediment supplies and multi-stage canyon fillings. The Pearl River Canyon System’s formation is closely related to the development of Pearl River Delta. Its vertical stacking and migrating canyon patterns have changed over time. The depositional architectures and evolution of the recent Penghu-Gaoping Canyon System respond to tectonic movements along the Taiwan-Luzon convergent continental margin. The main controlling factors of the formation and evolution of these three canyon systems include the tectonic setting, sediment supply, sea level change and paleo-geomorphology, among which the former two are dominant. The Penghu-Gaoping Canyon System formed along the subduction structural zone, directly indicating a typical tectonic origin. Numerous seismic data show that the Central Canyon and Pearl River Canyon systems are obviously affected by tectonics, associated local topography and sediment supply. %0 journal article %@ 2296-665X %A Benkort, D., Daewel, U., Heath, M., Schrum, C. %D 2020 %J Frontiers in Environmental Science %P 548013 %R doi:10.3389/fenvs.2020.548013 %T On the Role of Biogeochemical Coupling Between Sympagic and Pelagic Ecosystem Compartments for Primary and Secondary Production in the Barents Sea %U https://doi.org/10.3389/fenvs.2020.548013 %X Primary production in the Arctic marine system is principally due to pelagic phytoplankton. In addition, sea-ice algae also make a contribution and play an important role in food web dynamics. A proper representation of sea-ice algae phenology and the linkage with the pelagic and benthic systems is needed, so as to better understand the ecosystem response to warming and shrinking ice cover. Here we describe the extension of the biogeochemical model ECOSMO II to include a sympagic system in the model formulation, illustrated by implementation in the Barents Sea. The new sympagic system formulation includes four nutrients (NO3, NH4, PO4, and SiO2), one functional group for sea-ice algae and one detritus pool, and exchanges with the surface ocean layer. We investigated the effects of linkage between the three systems (sympagic, pelagic, and benthic) on the ecosystem dynamic; the contribution of the ice algae to total primary production; and how the changes in ice coverage will affect the lower trophic level Arctic food-web dynamics. To solve the scientific and technical challenges related to the coupling, the model was implemented in a 1D application of the General Ocean Turbulence Model (GOTM). Results showed that the model simulated the seasonal pattern of the sympagic components realistically when compared to the current knowledge of the Barents Sea. Our results show that the sympagic system influences the timing and the amplitude of the pelagic primary and secondary production in the water column. We also demonstrated that sea-ice algae production leads to seeding of pelagic diatoms and an enhancement of the zooplankton production. Finally, we used the model to explain how the interaction between zooplankton and ice algae can control the pelagic primary production in the Barents Sea. %0 journal article %@ 0941-2948 %A Platis, A., Bange, J., Bärfuss, K., Cañadillas, B., Hundhausen, M., Djath, B., Lampert, A., Schulz-Stellenfleth, J., Siederselben, S., Neumann, T., Emeis, S. %D 2020 %J Meteorologische Zeitschrift %N 5 %P 355-376 %R doi:10.1127/metz/2020/1023 %T Long-range modifications of the wind field by offshore wind parks – results of the project WIPAFF %U https://doi.org/10.1127/metz/2020/1023 5 %X This publication synthesizes the results of the WIPAFF (WInd PArk Far Fields) project. WIPAFF focused on the far field of large offshore wind park wakes (more than 5 km downstream of the wind parks) located in the German North Sea. The research project combined in situ aircraft and remote sensing measurements, satellite SAR data analysis and model simulations to enable a holistic coverage of the downstream wakes. The in situ measurements recorded on-board the research aircraft DO‑128 and remote sensing by laser scanner and SAR prove that wakes of more than 50 kilometers exist under certain atmospheric conditions. Turbulence occurs at the lateral boundaries of the wakes, due to shear between the reduced wind speed inside the wake and the undisturbed flow. The results also reveal that the atmospheric stability plays a major role in the evolution of wakes and can increase the wake length significantly by a factor of three or more. On the basis of the observations existing mesoscale and industrial models were validated and updated. The airborne measurement data is available at PANGAEA/ESSD. %0 journal article %@ 0079-6611 %A Benkort, D., Lavoie, D., Plourde, S., Dufresne, C., Maps, F. %D 2020 %J Progress in Oceanography %P 102270 %R doi:10.1016/j.pocean.2020.102270 %T Arctic and Nordic krill circuits of production revealed by the interactions between their physiology, swimming behaviour and circulation %U https://doi.org/10.1016/j.pocean.2020.102270 %X The two species Thysanoessa raschii and Meganyctiphanes norvegica dominate the krill biomass of the Estuary and Gulf of St. Lawrence (EGSL) ecosystem. The EGSL is the southernmost limit of seasonal sea-ice cover in the North Atlantic and constitutes a dynamic frontier between Arctic and Atlantic water masses. In order to better understand the complex mechanisms underpinning the spatio-temporal dynamics of the production and distribution of these keystone forage species in the EGSL, we coupled in a Lagrangian framework an individual-based model (IBM) of krill physiology to a three-dimensional regional circulation model and a NPZD-type biogeochemical model. Our results show that the spatio-temporal production dynamics of both krill species was principally controlled by their food dynamics. Our numerical analyses highlighted the potential areas of krill production within the EGSL during spring and summer. We confirmed that the St. Lawrence Estuary was the most productive area, and we show that it subsidizes the central and southern Gulf during most of the growing season. The Estuary is part of a larger cyclonic circuit of krill production and transport that runs along the shores of most of the EGSL and the slope of the Laurentian Channel. %0 journal article %@ 0964-5691 %A Elliott, M., Borja, Á., Cormier, R. %D 2020 %J Ocean and Coastal Management %P 105315 %R doi:10.1016/j.ocecoaman.2020.105315 %T Managing marine resources sustainably: A proposed integrated systems analysis approach %U https://doi.org/10.1016/j.ocecoaman.2020.105315 %X Marine and estuarine management requires an excellent understanding of the interacting, interrelated and interdependent sub-systems comprising ecological, societal and management complexity. Managing such a complex system sustainably relies on knowing what aspects can be managed, and conversely what aspects are outside the control of the manager. Accordingly, by taking elements from existing environmental management approaches, especially in Europe and Canada, here we propose an integrated systems analysis approach which links 14 component sub-systems. Using these cases shows that while all elements exist, they have hitherto not been combined into a holistic decision support system. These components are linked here in a cycle of three Parts - (A) defining the policy problems facing the seas, (B) obtaining the relevant and fit-for-purpose natural and social sciences data and information, and (C) creating an input for policy and decision-making which involves stakeholders. The component sub-systems are: an Underpinning Framework Sub-system (1), which then leads to the Issue Sub-system (2), which is vision-related and includes causes and/or consequences of pressures to be managed. The Ecological Sub-system (3) links the biota and its environment to the Socio-ecological Sub-system (4) and the Socio-economic subsystem (5), which considers the macroeconomic aspects. The Resources and Delivery Sub-system (6) considers which scientists do what and how do they do it and the Provenance Sub-system (7) checks that there is a fit-for-purpose and defendable science evidence base. The Governance Sub-system (8), incorporates policies and politics as well as horizontally and vertically integrating the Legislative (8A) and the Administrative Sub-systems (8B). The Communication (8C) and Stakeholder Sub-systems (8D) ensure involvement across the stakeholder typology (of formal and informal actors). Finally, the Achievement Sub-system (9) and the Feedback Sub-system (10) ensures that all of these actions achieve successful and sustainable marine resource management. %0 journal article %@ 1812-0784 %A Tchilibou, M., Gourdeau, L., Lyard, F., Morrow, R., Koch Larrouy, A., Allain, D., Djath, B. %D 2020 %J Ocean Science %N 3 %P 615-635 %R doi:10.5194/os-16-615-2020 %T Internal tides in the Solomon Sea in contrasted ENSO conditions %U https://doi.org/10.5194/os-16-615-2020 3 %X Intense equatorward western boundary currents transit the Solomon Sea, where active mesoscale structures exist with energetic internal tides. In this marginal sea, the mixing induced by these features can play a role in the observed water mass transformation. The objective of this paper is to document the M2 internal tides in the Solomon Sea and their impacts on the circulation and water masses, based on two regional simulations with and without tides. Since the Solomon Sea is under the influence of ENSO, the characteristics of the internal tides are also analyzed for two contrasted conditions: the January–March 1998 El Niño and the April–June 1999 La Niña. The generation, propagation, and dissipation of the internal tides are sensitive to changes in stratification and mesoscale activity, and these differ between these contrasted El Niño and La Niña case studies. Mode 1 is the dominant vertical mode to propagate baroclinic tidal energy within the Solomon Sea, but mode 2 becomes more energetic during the El Niño period when the stratification is closer to the surface. The La Niña period with a higher level of mesoscale activity exhibits more incoherent internal tides. These results illustrate the complexity of predicting internal tides in marginal seas in order to clearly observe meso- and submesoscale signatures from altimetric missions, including the future Surface Water Ocean Topography (SWOT) mission. Diapycnal mixing induced by tides contributes to a stronger erosion of the salinity maximum of the upper thermocline water and to cooling of the surface temperature interacting with the atmosphere. Such effects are particularly visible in quieter regions, where particles may experience the tidal effects over a longer time. However, when averaged over the Solomon Sea, the tidal effect on water mass transformation is an order of magnitude less than that observed at the entrance and exits of the Solomon Sea. These localized sites appear crucial for diapycnal mixing, since most of the baroclinic tidal energy is generated and dissipated locally here, and the different currents entering/exiting the Solomon Sea merge and mix. Finally, the extreme ENSO condition case studies suggest the strong role of local circulation changes, as well as stratification changes, in modifying the internal tides. %0 journal article %@ 2169-9275 %A Zhang, Z., Stanev, E., Grayek, S. %D 2020 %J Journal of Geophysical Research : Oceans %N 12 %P e2020JC016402 %R doi:10.1029/2020JC016402 %T Reconstruction of the Basin‐Wide Sea‐Level Variability in the North Sea Using Coastal Data and Generative Adversarial Networks %U https://doi.org/10.1029/2020JC016402 12 %X We present an application of generative adversarial networks (GANs) to reconstruct the sea level of the North Sea using a limited amount of data from tidal gauges (TGs). The application of this technique, which learns how to generate datasets with the same statistics as the training set, is explained in detail to ensure that interested scientists can implement it in similar or different oceanographic cases. Training is performed for all of 2016, and the model is validated on data from 3 months in 2017 and compared against reconstructions using the Kalman filter approach. Tests with datasets generated by an operational model (“true data”) demonstrated that using data from only 19 locations where TGs permanently operate is sufficient to generate an adequate reconstruction of the sea surface height (SSH) in the entire North Sea. The machine learning approach appeared successful when learning from different sources, which enabled us to feed the network with real observations from TGs and produce high‐quality reconstructions of the basin‐wide SSH. Individual reconstruction experiments using different combinations of training and target data during the training and validation process demonstrated similarities with data assimilation when errors in the data and model were not handled appropriately. The proposed method demonstrated good skill when analyzing both the full signal and the low‐frequency variability only. It was demonstrated that GANs are also skillful at learning and replicating processes with multiple time scales. The different skills in different areas of the North Sea are explained by the different signal‐to‐noise ratios associated with differences in regional dynamics. %0 journal article %@ 0308-597X %A Stojanovic, T., Gee, K. %D 2020 %J Marine Policy %P 104115 %R doi:10.1016/j.marpol.2020.104115 %T Governance as a framework to theorise and evaluate marine planning %U https://doi.org/10.1016/j.marpol.2020.104115 %X Marine Planning seems to offer promise to integrate oceans governance with a prospective approach to sustainability, most distinctively through the process of creating a spatial strategy contained in a marine plan, hence ‘marine spatial planning’. This paper will show that in order to understand whether marine planning really is leading towards sustainability, recourse to governance theory will be required. Governance theory can provide principles or a theoretical framework for marine planning systems. It can also inform practicable planning, particularly in the phase of setting evaluatory criteria—a phase that many policy analysts consider should logically proceed the implementation of marine plans themselves—but also in broader questions of institutional design. Yet researchers and practitioners are faced with a situation in which there a multiple, competing approaches to governance from which to choose, some of which were developed in terrestrial contexts, raising questions about their applicability to the marine environment. This paper outlines five key major theoretical approaches for governance and reviews analytical debates and empirical findings about marine planning using those approaches. The core question of this study is which theoretical approaches offer the most traction for evaluating MSP and why? %0 journal article %@ 2169-9275 %A Chegini, F., Holtermann, P., Kerimoglu, O., Becker, M., Kreus, M., Klingbeil, K., Gräwe, U., Winter, C., Burchard, H. %D 2020 %J Journal of Geophysical Research : Oceans %N 8 %P e2019JC015987 %R doi:10.1029/2019JC015987 %T Processes of Stratification and Destratification During An Extreme River Discharge Event in the German Bight ROFI %U https://doi.org/10.1029/2019JC015987 8 %X Processes of stratification and destratification in the German Bight region of fresh water influence (ROFI) are investigated following an extreme river discharge event in June 2013. For this purpose, a high-resolution baroclinic ocean model is set up and validated against field data. The model results are used to study the temporal and spatial variability of stratification and the duration of persistent stratification in 2013. The relevant processes affecting stratification are investigated by analyzing the potential energy anomaly budget, with a focus on mixing and tidal straining. It is shown that the stratification in the German Bight is highly affected by the spring-neap tidal cycle, with generally less stratification at spring tides due to dominant tidal mixing. It is also shown that the location of the river plume can modify this pattern. During spring tides, if the river plume is confined to the eastern region, stratification decreases significantly, as expected, due to the dominance of mixing over tidal straining. On the other hand, if the river plume moves toward deeper regions at spring tides, strong tidal straining becomes present. In this condition, mixing is weak, and the dominant tidal straining results in persistent stratification. %0 journal article %@ 2071-1050 %A Saunders, F., Gilek, M., Ikauniece, A., Tafon, R., Gee, K., Zaucha, J. %D 2020 %J Sustainability %N 6 %P 2560 %R doi:10.3390/su12062560 %T Theorizing Social Sustainability and Justice in Marine Spatial Planning: Democracy, Diversity, and Equity %U https://doi.org/10.3390/su12062560 6 %X This article elaborates a conceptual framework to examine social sustainability in marine spatial planning (MSP). Based on a critical literature review of key texts on social sustainability in MSP and the broader sustainable development literature we show the need to elaborate a cogent and comprehensive approach for the analysis and pursuit of social sustainability linked to the sea. We then theorize social sustainability by developing a conceptual framework through integrating three dimensions: Recognition, Representation and Distribution. While these three social sustainability/justice features clearly overlap and are interdependent in practice, the conceptual thinking underpinning each of them is distinctive and when taken together they contribute towards conceiving social sustainability as a pillar of sustainability. Our approach can support an analysis/evaluation of MSP in that, first, its broad scope and adaptability makes it suitable to examine the wide range of claims, demands, and concerns that are likely to be encountered across different practical MSP settings. Second, it acknowledges the opportunities and challenges of assessing, implementing, and achieving social justice within a broader sustainability framework. %0 journal article %@ 2328-4277 %A Lange, S., Volkholz, J., Geiger, T., Zhao, F., Vega, I., Veldkamp, T., Reyer, C.P.O., Warszawski, L., Huber, V., Jägermeyr, J., Schewe, J., Bresch, D.N., Büchner, M., Chang, J., Ciais, P., Dury, M., Emanuel, K., Folberth, C., Gerten, D., Gosling, S.N., Grillakis, M., Hanasaki, N., Henrot, A.-J., Hickler, T., Honda, Y., Ito, A., Khabarov, N., Koutroulis, A., Liu, W., Müller, C., Nishina, K., Ostberg, S., Müller Schmied, H., Seneviratne, S.I., Stacke, T., Steinkamp, J., Thiery, W., Wada, Y., Willner, S., Yang, H., Yoshikawa, M., Yue, C., Frieler, K. %D 2020 %J Earth’s Future %N 12 %P e2020EF001616 %R doi:10.1029/2020EF001616 %T Projecting Exposure to Extreme Climate Impact Events Across Six Event Categories and Three Spatial Scales %U https://doi.org/10.1029/2020EF001616 12 %X The extent and impact of climate‐related extreme events depend on the underlying meteorological, hydrological, or climatological drivers as well as on human factors such as land use or population density. Here we quantify the pure effect of historical and future climate change on the exposure of land and population to extreme climate impact events using an unprecedentedly large ensemble of harmonized climate impact simulations from the Inter‐Sectoral Impact Model Intercomparison Project phase 2b. Our results indicate that global warming has already more than doubled both the global land area and the global population annually exposed to all six categories of extreme events considered: river floods, tropical cyclones, crop failure, wildfires, droughts, and heatwaves. Global warming of 2°C relative to preindustrial conditions is projected to lead to a more than fivefold increase in cross‐category aggregate exposure globally. Changes in exposure are unevenly distributed, with tropical and subtropical regions facing larger increases than higher latitudes. The largest increases in overall exposure are projected for the population of South Asia. %0 journal article %@ 0048-9697 %A Lauerburg, R.A.M., Diekmann, R., Blanz, B., Gee, K., Held, H., Kannen, A., Möllmann, C., Probst, W.N., Rambo, H., Cormier, R., Stelzenmüller, V. %D 2020 %J Science of the Total Environment %P 135838 %R doi:10.1016/j.scitotenv.2019.135838 %T Socio-ecological vulnerability to tipping points: A review of empirical approaches and their use for marine management %U https://doi.org/10.1016/j.scitotenv.2019.135838 %X Sustainability in the provision of ecosystem services requires understanding of the vulnerability of social-ecological systems (SES) to tipping points (TPs). Assessing SES vulnerability to abrupt ecosystem state changes remains challenging, however, because frameworks do not operationally link ecological, socio-economic and cultural elements of the SES. We conducted a targeted literature review on empirical assessments of SES and TPs in the marine realm and their use in ecosystem-based management. Our results revealed a plurality of terminologies, definitions and concepts that hampers practical operationalisation of these concepts. Furthermore, we found a striking lack of socio-cultural aspects in SES vulnerability assessments, possibly because of a lack of involvement of stakeholders and interest groups. We propose guiding principles for assessing vulnerability to TPs that build on participative approaches and prioritise the connectivity between SES components by accounting for component linkages, cascading effects and feedback processes. %0 journal article %@ 1726-4170 %A Kerimoglu, O., Voynova, Y., Chegini, F., Brix, H., Callies, U., Hofmeister, R., Klingbeil, K., Schrum, C., van Beusekom, J. %D 2020 %J Biogeosciences %N 20 %P 5097-5127 %R doi:10.5194/bg-17-5097-2020 %T Interactive impacts of meteorological and hydrological conditions on the physical and biogeochemical structure of a coastal system %U https://doi.org/10.5194/bg-17-5097-2020 20 %X The German Bight was exposed to record high riverine discharges in June 2013, as a result of flooding of the Elbe and Weser rivers. Several anomalous observations suggested that the hydrodynamical and biogeochemical states of the system were impacted by this event. In this study, we developed a biogeochemical model and coupled it with a previously introduced high-resolution hydrodynamical model of the southern North Sea in order to better characterize these impacts and gain insight into the underlying processes. Performance of the model was assessed using an extensive set of in situ measurements for the period 2011–2014. We first improved the realism of the hydrodynamic model with regard to the representation of cross-shore gradients, mainly through inclusion of flow-dependent horizontal mixing. Among other characteristic features of the system, the coupled model system can reproduce the low salinities, high nutrient concentrations and low oxygen concentrations in the bottom layers observed within the German Bight following the flood event. Through a scenario analysis, we examined the sensitivity of the patterns observed during July 2013 to the hydrological and meteorological forcing in isolation. Within the region of freshwater influence (ROFI) of the Elbe–Weser rivers, the flood event clearly dominated the changes in salinity and nutrient concentrations, as expected. However, our findings point to the relevance of the peculiarities in the meteorological conditions in 2013 as well: a combination of low wind speeds, warm air temperatures and cold bottom-water temperatures resulted in a strong thermal stratification in the outer regions and limited vertical nutrient transport to the surface layers. Within the central region, the thermal and haline dynamics interactively resulted in an intense density stratification. This intense stratification, in turn, led to enhanced primary production within the central region enriched by nutrients due to the flood but led to reduction within the nutrient-limited outer region, and it caused a widespread oxygen depletion in bottom waters. Our results further point to the enhancement of the current velocities at the surface as a result of haline stratification and to intensification of the thermohaline estuarine-like circulation in the Wadden Sea, both driven by the flood event. %0 journal article %@ 0964-5691 %A Kidd, S., Calado, H., Gee, K., Gilek, M., Saunders, F. %D 2020 %J Ocean and Coastal Management %P 105182 %R doi:10.1016/j.ocecoaman.2020.105182 %T Marine Spatial Planning and sustainability: Examining the roles of integration - Scale; policies; stakeholders and knowledge %U https://doi.org/10.1016/j.ocecoaman.2020.105182 %X Marine Spatial Planning (MSP) has been heralded as the key means of achieving a more integrated approach to marine use across sectors and spatial scales. Achieving greater integration and coherence in MSP governance arrangements is seen as a way to resolve current problems of marine governance (such as fragmentation) and address future resource demands in a sustainable way. However, there is a lack of clarity and consensus in practice regarding sustainability in MSP, both in terms of MSP governance practices and sustainable resource use. For example, how are we to treat the environment in MSP? Should we conceive the environment as just another sector with interests to be negotiated, or as the very boundary condition that limits possibilities for maritime activities and developments? How do we integrate diverse views on this in MSP decision-making? This is but one example of an integration challenge in MSP important for sustainability. There are numerous others. Integration is intimately connected to the ability of MSP to deliver sustainable marine resource use at various levels and scales. The roles of integration are diverse and interconnected, including those that affect social-ecological integration or land-sea interaction, but also aspects of good governance and social sustainability. The latter include inter-sectoral decisionmaking, stakeholder engagement, cross-border interaction and knowledge pluralism. How integration is exercised in these procedural aspects of MSP is likely to substantively affect outcomes both in terms of sustainable blue growth or the ability to deliver an ecosystem-based approach. Integration as a policy and analytical problem to be addressed has also been discussed elsewhere – most saliently in the fields of sustainable development, ICZM, environmental policy integration, planning theory and socio-ecological systems. While there has been some work on integration in MSP, additional insight is needed: to better empirically ground the roles of integration in MSP, to understand the multidimensionality and interdependencies of integration dimensions and to unpack what ‘balance’ might mean for understanding and pursuing sustainability in different MSP contexts. %0 journal article %@ 1811-1602 %A Abram, N., Bothe, O., Eggleston, S., Konecky, B., Linderholm, H., Martrat, B., McGregor, H., Phipps, S., St. George, S. %D 2020 %J Past Global Changes Magazine %N 2 %P 66 %R doi:10.22498/pages.28.2.66 %T PAGES 2k Network community survey %U https://doi.org/10.22498/pages.28.2.66 2 %X %0 journal article %@ 2211-4645 %A Finke, G., Gee, K., Gxaba, T., Sorgenfrei, R., Russo, V., Pinto, D., Nsiangango, S.E., Sousa, L.N., Braby, R., Alves, F.L., Heinrichs, B., Kreiner, A., Amunyela, M., Popose, G., Ramakulukusha, M., Naidoo, A., Mausolf, E., Nsingi, K.K. %D 2020 %J Environmental Development %P 100569 %R doi:10.1016/j.envdev.2020.100569 %T Marine Spatial Planning in the Benguela Current Large Marine Ecosystem %U https://doi.org/10.1016/j.envdev.2020.100569 %X The Benguela Current Large Marine Ecosystem (BCLME) in the south-east Atlantic covers the territorial waters and Exclusive Economic Zones (EEZ's) of Angola and Namibia and partly of South Africa. Increasing demands, user-user and user-environment conflicts occur throughout the area. The three countries, which are parties to the Benguela Current Convention (BCC), have begun to implement Marine Spatial Planning (MSP) to support the sustainable development of the area and enhance ocean governance. This makes the region one of the first in a developing economies context and on the African continent to introduce MSP. The article (1) traces the origin of MSP in the region and describes the reasons for its development, (2) reviews the status of MSP processes to date at the regional and national level, and (3) reflects on the regional and individual country processes in terms of differences and similarities in approach and process governance, shared opportunities and difficulties. The study finds that MSP in the region is introduced because of both strong interests to use it as a means to help grow the blue/ocean economy and as a mechanism to further the implementation of the ecosystem approach. Similar steps have been taken so far and alike approaches to MSP exist across the three countries, with the BCC as regional convention facilitating knowledge sharing and assisting to improve cross-border coherence and consistency on MSP from the outset. Although challenges, such as limited finances and data gaps exist both at national and regional level, the MSP processes to-date have created an enabling environment to develop the first marine spatial plans in each country and to exchange knowledge and experiences within the region and with other regions. %0 journal article %@ 1812-0784 %A Mathis, M., Mikolajewicz, U. %D 2020 %J Ocean Science %N 1 %P 167-193 %R doi:10.5194/os-16-167-2020 %T The impact of meltwater discharge from the Greenland ice sheet on the Atlantic nutrient supply to the northwest European shelf %U https://doi.org/10.5194/os-16-167-2020 1 %X Projected future shoaling of the wintertime mixed layer in the northeast (NE) Atlantic has been shown to induce a regime shift in the main nutrient supply pathway from the Atlantic to the northwest European shelf (NWES) near the end of the 21st century. While reduced winter convection leads to a substantial decrease in the vertical nutrient supply and biological productivity in the open ocean, vertical mixing processes at the shelf break maintain a connection to the subpycnocline nutrient pool and thus productivity on the shelf. Here, we investigate how meltwater discharge from the Greenland ice sheet (GIS), not yet taken into account, impacts the mixed layer shoaling and the regime shift in terms of spatial distribution and temporal variability. To this end, we have downscaled sensitivity experiments by a global Earth system model for various GIS melting rates with a regionally coupled ocean–atmosphere climate system model. The model results indicate that increasing GIS meltwater discharge leads to a general intensification of the regime shift. Atlantic subpycnocline water masses mixed up at the shelf break become richer in nutrients and thus further limit the projected nutrient decline on the shelf. Moreover, the stronger vertical nutrient gradient through the pycnocline results in an enhanced interannual variability of on-shelf nutrient fluxes which, however, do not significantly increase variations in nutrient concentrations and primary production on the shelf. Due to the impact of the GIS meltwater discharge on the NE Atlantic mixed layer depth, the regime shift becomes initiated earlier in the century. The effect on the onset timing, though, is found to be strongly damped by the weakening of the Atlantic meridional overturning circulation. A GIS melting rate that is even 10 times higher than expected for emission scenario Representative Concentration Pathway (RCP) 8.5 would not lead to an onset of the regime shift until the 2070s. %0 journal article %@ 0025-326X %A Elliott, M., Borja, Á., Cormier, R. %D 2020 %J Marine Pollution Bulletin %P 111201 %R doi:10.1016/j.marpolbul.2020.111201 %T Activity-footprints, pressures-footprints and effects-footprints – Walking the pathway to determining and managing human impacts in the sea %U https://doi.org/10.1016/j.marpolbul.2020.111201 %X Determining the overall effects of human activities on the estuaries, seas and coasts, as a precursor to marine management, requires quantifying three aspects. These are: (a) the area in which the human activities take place, (b) the area covered by the pressures generated by the activities on the prevailing habitats and species, in which pressures are defined as the mechanisms of change, and (c) the area over which any adverse effects occur. These features can be respectively termed the activities-footprints, the pressures-footprints and the effects-footprints. The latter in turn incorporates both the effects on the natural system and the effects on ecosystem services from which society extracts goods and benefits. This viewpoint article explains the rationale behind this typology and proposes definitions for each of these three types of footprints. %0 journal article %@ 0165-0009 %A Gädeke, A., Krysanova, V., Aryal, A., Chang, J., Grillakis, M., Hanasaki, N., Koutroulis, A., Pokhrel, Y., Satoh, Y., Schaphoff, S., Müller Schmied, H., Stacke, T., Tang, Q., Wada, Y., Thonicke, K. %D 2020 %J Climatic Change %P 1329-1351 %R doi:10.1007/s10584-020-02892-2 %T Performance evaluation of global hydrological models in six large Pan-Arctic watersheds %U https://doi.org/10.1007/s10584-020-02892-2 %X Global Water Models (GWMs), which include Global Hydrological, Land Surface, and Dynamic Global Vegetation Models, present valuable tools for quantifying climate change impacts on hydrological processes in the data scarce high latitudes. Here we performed a systematic model performance evaluation in six major Pan-Arctic watersheds for different hydrological indicators (monthly and seasonal discharge, extremes, trends (or lack of), and snow water equivalent (SWE)) via a novel Aggregated Performance Index (API) that is based on commonly used statistical evaluation metrics. The machine learning Boruta feature selection algorithm was used to evaluate the explanatory power of the API attributes. Our results show that the majority of the nine GWMs included in the study exhibit considerable difficulties in realistically representing Pan-Arctic hydrological processes. Average APIdischarge (monthly and seasonal discharge) over nine GWMs is > 50% only in the Kolyma basin (55%), as low as 30% in the Yukon basin and averaged over all watersheds APIdischarge is 43%. WATERGAP2 and MATSIRO present the highest (APIdischarge > 55%) while ORCHIDEE and JULES-W1 the lowest (APIdischarge ≤ 25%) performing GWMs over all watersheds. For the high and low flows, average APIextreme is 35% and 26%, respectively, and over six GWMs APISWE is 57%. The Boruta algorithm suggests that using different observation-based climate data sets does not influence the total score of the APIs in all watersheds. Ultimately, only satisfactory to good performing GWMs that effectively represent cold-region hydrological processes (including snow-related processes, permafrost) should be included in multi-model climate change impact assessments in Pan-Arctic watersheds. %0 journal article %@ 0894-8755 %A Jensen, L., Eicker, A., Stacke, T., Dobslaw, H. %D 2020 %J Journal of Climate %N 21 %P 9497-9509 %R doi:10.1175/JCLI-D-20-0042.1 %T Predictive Skill Assessment for Land Water Storage in CMIP5 Decadal Hindcasts by a Global Reconstruction of GRACE Satellite Data %U https://doi.org/10.1175/JCLI-D-20-0042.1 21 %X The evaluation of decadal climate predictions against observations is crucial for their benefit to stakeholders. While the skill of such forecasts has been verified for several atmospheric variables, land hydrological states such as terrestrial water storage (TWS) have not been extensively investigated yet due to a lack of long observational records. Anomalies of TWS are globally observed with the satellite missions GRACE (2002–2017) and GRACE-FO (since 2018). By means of a GRACE-like reconstruction of TWS available over 41 years, we demonstrate that this data type can be used to evaluate the skill of decadal prediction experiments made available from different Earth system models as part of both CMIP5 and CMIP6. Analysis of correlation and root-mean-square deviation (RMSD) reveals that for the global land average the initialized simulations outperform the historical experiments in the first three forecast years. This predominance originates mainly from equatorial regions where we assume a longer influence of initialization due to longer soil memory times. Evaluated for individual grid cells, the initialization has a largely positive effect on the forecast year 1 TWS states; however, a general grid-scale prediction skill for TWS of more than 2 years could not be identified in this study for CMIP5. First results from decadal hindcasts of three CMIP6 models indicate a predictive skill comparable to CMIP5 for the multimodel mean in general, and a distinct positive influence of the improved soil–hydrology scheme implemented in the MPI-ESM for CMIP6 in particular. %0 journal article %@ 0048-9697 %A Stelzenmüller, V., Coll, M., Cormier, R., Mazaris, A.D., Pascual, M., Loiseau, C., Claudet, J., Katsanevakis, S., Gissi, E., Evagelopoulos, A., Rumes, B., Degraer, S., Ojaveer, H., Moller, T., Giménez, J., Piroddi, C., Markantonatou, V., Dimitriadis, C. %D 2020 %J Science of the Total Environment %P 138118 %R doi:10.1016/j.scitotenv.2020.138118 %T Operationalizing risk-based cumulative effect assessments in the marine environment %U https://doi.org/10.1016/j.scitotenv.2020.138118 %X Ecosystem-based management requires an assessment of the cumulative effects of human pressures and environmental change. The operationalization and integration of cumulative effects assessments (CEA) into decision-making processes often lacks a comprehensive and transparent framework. A risk-based CEA framework that divides a CEA in risk identification, risk analysis and risk evaluation, could structure such complex analyses and facilitate the establishment of direct science-policy links. Here, we examine carefully the operationalization of such a risk-based CEA framework with the help of eleven contrasting case studies located in Europe, French Polynesia, and Canada. We show that the CEA framework used at local, sub-regional, and regional scales allowed for a consistent, coherent, and transparent comparison of complex assessments. From our analysis, we pinpoint four emerging issues that, if accurately addressed, can improve the take up of CEA outcomes by management: 1) framing of the CEA context and defining risk criteria; 2) describing the roles of scientists and decision-makers; 3) reducing and structuring complexity; and 4) communicating uncertainty. Moreover, with a set of customized tools we describe and analyze for each case study the nature and location of uncertainty as well as trade-offs regarding available knowledge and data used for the CEA. Ultimately, these tools aid decision-makers to recognize potential caveats and repercussions of management decisions. One key recommendation is to differentiate CEA processes and their context in relation to governance advice, marine spatial planning or regulatory advice. We conclude that future research needs to evaluate how effective management measures are in reducing the risk of cumulative effects. Changing governance structures takes time and is often difficult, but we postulate that well-framed and structured CEA can function as a strategic tool to integrate ecosystem considerations across multiple sectorial policies. %0 journal article %@ 1812-0784 %A Li, Y., von Storch, H., Wang, Q., Zhou, Q., Tang, S. %D 2019 %J Ocean Science %N 6 %P 1455-1467 %R doi:10.5194/os-15-1455-2019 %T Testing the validity of regional detail in global analyses of sea surface temperature – the case of Chinese coastal waters %U https://doi.org/10.5194/os-15-1455-2019 6 %X We have designed a method for testing the quality of multidecadal analyses of sea surface temperature (SST) in regional seas by using a set of high-quality local SST observations. In recognizing that local data may reflect local effects, we focus on the dominant empirical orthogonal functions (EOFs) of the local data and of the localized data of the gridded SST analyses. We examine the patterns, variability, and trends of the principal components. This method is applied to examine three different SST analyses, i.e., HadISST1, ERSST, and COBE SST. They have been assessed using a newly constructed high-quality dataset of SST at 26 coastal stations along the Chinese coast in 1960–2015, which underwent careful examination with respect to quality and a number of corrections for inhomogeneities. The three gridded analyses perform generally well from 1960 to 2015, in particular since 1980. However, for the pre-satellite period prior to the 1980s, the analyses differ among each other and show some inconsistencies with the local data, such as artificial break points, periods of bias, and differences in trends. We conclude that gridded SST analyses need improvement in the pre-satellite period (prior to the 1980s) by reexamining in detail archives of local quality-controlled SST data in many data-sparse regions of the world. %0 journal article %@ 0170-6012 %A Ludwig, T., Geyer, B. %D 2019 %J Informatik Spektrum %N 1 %P 48-52 %R doi:10.1007/s00287-019-01149-2 %T Reproduzierbarkeit %U https://doi.org/10.1007/s00287-019-01149-2 1 %X Reproduzierbarkeit von Forschungsergebnissen gehört zu den grundlegenden Qualitätskriterien in der Wissenschaft. Auf Betreiben Robert Boyles wurde ab der Mitte des 17. Jahrhunderts erstmals eine Forderung nach Transparenz des wissenschaftlichen Erkenntnisprozessesin die Standards der Royal Society aufgenommen. Seit Beginn der 2010er-Jahre gewinnt dabei der Begriff der Reproduzierbarkeits-oderReplikationskrisezunehmend an Bedeutung. Ihren Ausgangspunktnahm diese als Methodenschwäche erkannte Problematik inden Sozialwissenschaften.InderPsychologie veröffentlichte Forschungsergebnissekonnten von unabhängigen Wissenschaftlern in Replikationsstudien mehrfach nicht nachvollzogen werden. Die Wissenschaft diskutiert methodische VerbesserungenhierzuunterdenÜberschriftenOpenData und Open Science [ 7].ImvorliegendenSchlagwort konzentrieren wir uns auf die computergestützten Wissenschaftenundinsbesondereaufdiecomputerbasierte Klimaforschung als ein Beispielfür die zu diskutierendenFragestellungen. %0 journal article %@ 2190-4979 %A Tim, N., Zorita, E., Emeis, K., Schwarzkopf, F., Biastoch, A., Hünicke, B. %D 2019 %J Earth System Dynamics %N 4 %P 847-858 %R doi:10.5194/esd-10-847-2019 %T Analysis of the position and strength of westerlies and trades with implications for Agulhas leakage and South Benguela upwelling %U https://doi.org/10.5194/esd-10-847-2019 4 %X The westerlies and trade winds over the South Atlantic and Indian Ocean are important drivers of the regional oceanography around southern Africa, including features such as the Agulhas Current, the Agulhas leakage, and the Benguela upwelling. Agulhas leakage constitutes a fraction of warm and saline water transport from the Indian Ocean into the South Atlantic. The leakage is stronger during intensified westerlies. Here, we analyze the wind stress of different observational and modeled atmospheric data sets (covering the last 2 millennia, the recent decades, and the 21st century) with regard to the intensity and position of the southeasterly trades and the westerlies. The analysis reveals that variations of both wind systems go hand in hand and that a poleward shift of the westerlies and trades and an intensification of westerlies took place during the recent decades. Furthermore, upwelling in South Benguela is slightly intensified when trades are shifted poleward. Projections for strength and position of the westerlies in the 21st century depend on assumed CO2 emissions and on their effect relative to the ozone forcing. In the strongest emission scenario (RCP8.5) the simulations show a further southward displacement, whereas in the weakest emission scenario (RCP2.6) a northward shift is modeled, possibly due to the effect of ozone recovery dominating the effect of anthropogenic greenhouse forcing. We conclude that the Agulhas leakage has intensified during the last decades and is projected to increase if greenhouse gas emissions are not reduced. This will have a small impact on Benguela upwelling strength and may also have consequences for water mass characteristics in the upwelling region. An increased contribution of Agulhas water to the upwelling water masses will import more preformed nutrients and oxygen into the upwelling region. %0 journal article %@ 0025-3227 %A Yin, S., Hernández-Molina, F., Zhang, W., Li, J., Wang, L., Ding, W. %D 2019 %J Marine Geology %P 105967 %R doi:10.1016/j.margeo.2019.105967 %T The influence of oceanographic processes on contourite features: A multidisciplinary study of the northern South China Sea %U https://doi.org/10.1016/j.margeo.2019.105967 %X This study examines how multiscale oceanographic processes interact with the seafloor to influence the development of contourite features in northern part of the South China Sea. The multidisciplinary approach used in this study combines physical oceanographic monitoring, numerical simulation, multibeam echosounding, seismic reflection profiling, and sediment core interpretation. The contourites detected and interpreted herein include depositional (drifts and sediment waves), erosional (channels, moats and furrows), and mixed erosional and depositional features (terraces and irregular depressions). This study finds that climatic variation influences the intensity of quasi-steady, along-slope regional water circulation which in turn influences the long-term development of primary (10–100 km) contourite depositional systems. Energetic but intermittent oceanographic processes (such as eddies and internal waves) generate smaller secondary features within the contourite depositional systems resulting in a complex, local seafloor morphology. Westward to south-westward migrating mesoscale eddies locally enhance regional water mass circulation and trigger sub-mesoscale flows which can generate (1–10 km) irregular depressions along their paths. Westward-propagating internal solitary waves form sedimentary waves. With the aid of numerical modelling results, a sedimentary model is proposed to explain how oceanographic processes influence sedimentary processes and determine a hierarchy of associated feature formation. This model can help advance understanding of how bottom currents influence sedimentary processes along continental margins and abyssal plains. %0 journal article %@ 0921-8181 %A Lemos, G., Semedo, A., Dobrynin, M., Behrens, A., Staneva, J., Bidlot, J.-R., Miranda, P.M.A. %D 2019 %J Global and Planetary Change %P 69-87 %R doi:10.1016/j.gloplacha.2018.09.011 %T Mid-twenty-first century global wave climate projections: Results from a dynamic CMIP5 based ensemble %U https://doi.org/10.1016/j.gloplacha.2018.09.011 %X Ocean surface gravity waves are part of the climate system, regulating the exchange of energy and momentum at the atmosphere-ocean interface. Besides that, waves have a direct impact on coastal erosion and sediment transport, in ship routing and offshore/ship infrastructure design, as well as in coastal management. Most future wave climate projections point out to statistically significant changes in wave height conditions in the global ocean towards the end of the 21st century. In the present study, the near future impact of a warmer climate on the global ocean wave climate towards the mid-21st century (2031–2060) is investigated through a 4-member “coherent” ensemble of wave climate projections: single-model (wave model WAM), single-forcing (EC-Earth) and single-scenario (RCP8.5). The wave model WAM was forced by wind speed and ice coverage from four Coupled Model Intercomparison Project Phase 5 (CMIP5) EC-Earth projections. The ensemble historic climate reference period has been evaluated by comparison against wave reanalysis/hindcast data, and wave in-situ observations. Statistically significant increases in the global mean wind speed, wave height, wave period and wave energy flux are to be expected towards the mid-twenty first century, in less than 50 years, these changes being more striking in the mid-to-high latitudes of the Southern Hemisphere. Due to the propagation of swell to lower latitudes, statistically significant increases in wave heights, periods and energy fluxes are also projected to occur in equatorial areas, especially along the eastern side of the main ocean basins, during the Austral winter. Comparatively, the projected changes in wave heights and energy fluxes are expected to occur more intensely during the first half of the 21st century, in several areas of the global ocean. %0 journal article %@ 0894-8755 %A Breivik, Ø., Carrasco, A., Staneva, J., Behrens, A., Semedo, A., Bidlot, J., Aarnes, O. %D 2019 %J Journal of Climate %N 6 %P 1677-1691 %R doi:10.1175/JCLI-D-18-0435.1 %T Global Stokes Drift Climate under the RCP8.5 Scenario %U https://doi.org/10.1175/JCLI-D-18-0435.1 6 %X The future Stokes drift climate is investigated using a global wave climate projection (2071–2100) forced with EC-EARTH winds under the RCP8.5 scenario. The future climate run is compared against a historical run (1976–2005). The Stokes drift climate is analyzed in terms of Stokes transport and surface Stokes drift. The impact on Stokes drift from changes to the wind, wind sea, and swell climate is identified. The consequences for upper-ocean mixing and circulation are studied by investigating the turbulent Langmuir number and the Stokes depth. The historical climate run is also compared to a hindcast with ERA-Interim forcing. Systematic discrepancies due to differences in resolution and model physics are identified, but no fundamental weaknesses are uncovered that should adversely affect the future run. As the surface Stokes drift is largely dictated by high-frequency waves, it is to a great degree controlled by changes to the local wind field, whereas the Stokes transport is more sensitive to swell. Both are expected to increase in the Southern Ocean by about 15%, while the North Atlantic sees a decrease of about 10%. The Stokes depth and the turbulent Langmuir number are set to change by about ±20% and ±10%, respectively. The changes to the Stokes depth suggest a deeper impact of the Coriolis–Stokes force in the Southern Ocean and a decrease in the northern extratropics. Changes to the KPP Langmuir-enhancement factor suggests potentially increased mixing in the Southern Ocean and a reduction in the North Atlantic and the North Pacific. %0 journal article %@ 0079-6611 %A Schartau, M., Riethmueller, R., Floeser, G., Beusekom, J.E.E.van, Krasemann, H., Hofmeister, R., Wirtz, K. %D 2019 %J Progress in Oceanography %P 231-250 %R doi:10.1016/j.pocean.2018.12.011 %T On the separation between inorganic and organic fractions of suspended matter in a marine coastal environment %U https://doi.org/10.1016/j.pocean.2018.12.011 %X A central aspect of coastal biogeochemistry is to determine how nutrients, lithogenic and organic matter are distributed and transformed within coastal and estuarine environments. Analyses of the spatio-temporal changes of total suspended matter (TSM) concentration indicate strong and variable linkages between intertidal fringes and pelagic regions. In particular, knowledge about the organic fraction of TSM provides insight to how biogenic and lithogenic particulate matter are distributed in suspension. In our study we take advantage of a set of over 3000 in situ Loss on Ignition (LoI) data from the Southern North Sea that represent fractions of particulate organic matter (POM) relative to TSM (LoI POM:TSM). We introduce a parameterization (POM-TSM model) that distinguishes between two POM fractions incorporated in TSM. One fraction is described in association with mineral particles. The other represents a seasonally varying fresh pool of POM. The performance of the POM-TSM model is tested against data derived from MERIS/ENVISAT-TSM products of the German Bight. Our analysis of remote sensing data exhibits specific qualitative features of TSM that can be attributed to distinct coastal zones. Most interestingly, a transition zone between the Wadden Sea and seasonally stratified regions of the Southern North Sea is identified where mineral associated POM appears in concentrations comparable to those of freshly produced POM. We will discuss how this transition is indicative for a zone of effective particle interaction and sedimentation.The dimension of this transition zone varies between seasons and with location. Our proposed POM-TSM model is generic and can be calibrated against in situ data of other coastal regions. %0 journal article %@ 0177-798X %A Georgievski, G., Hagemann, S. %D 2019 %J Theoretical and Applied Climatology %N 1-2 %P 1587-1603 %R doi:10.1007/s00704-018-2675-2 %T Characterizing uncertainties in the ESA-CCI land cover map of the epoch 2010 and their impacts on MPI-ESM climate simulations %U https://doi.org/10.1007/s00704-018-2675-2 1-2 %X Limitations of mapping land surface properties and their conversion into climate model boundary conditions are major sources of uncertainty in climate simulations. In this paper, the range of the largest possible uncertainty in satellite-derived land cover (LC) map is estimated and its impact on climate simulations is quantified with the Earth System Model of the Max-Planck Institute for Meteorology utilizing prescribed sea surface temperature and sea ice. Two types of uncertainty in the LC map are addressed: (i) uncertainty due to classification algorithm of spectral reflectance into LC classes, and (ii) uncertainty due to conversion of LC classes into the climate model vegetation distribution. For forest cover, each of them is about the same order of magnitude as the uncertainty range in recent observations (∼± 700 Mha). Superposing two sources of uncertainty results in LC maps that feature the range of vegetation deviation that is about the same order of magnitude as the recent (since year 1700) forest loss due to agriculture (forest cover uncertainty range ∼± 1700 Mha). These uncertainties in vegetation distribution lead to noticeable variations in near-surface climate variables, local, regional, and global climate forcing. Temperature does not show significant uncertainty in global mean, but rather exhibits regional deviations with an opposite response to LC uncertainty that compensate each other in the global mean (e.g., albedo feedback controls temperature in boreal North America resulting in cooling (warming) with decrease (increase) of vegetation while evaporative cooling controls temperature in South America and sub-Saharan Africa resulting in cooling (warming) with increase (decrease) of vegetation). Large-scale circulation is also affected by the LC uncertainty, and consequently precipitation pattern as well. It is demonstrated that precipitation uncertainty in the monsoonal regions are about the same order of magnitude as in previous studies with idealized perturbations of vegetation. These findings indicate that the range of uncertainty in satellite-derived vegetation maps for climate models is about the same order of magnitude as the uncertainty in recent observations of forest cover or as the forest lost due to agriculture. Consequently, climate simulations have a similar range of uncertainty in variables representing near-surface climate as the observed climate change due to land use. Hence, more accurate methods are needed for mapping and converting LC properties into model vegetation in order to increase reliability of climate model simulations. %0 journal article %@ 0930-7575 %A Vautard, R., Christidis, N., Ciavarella, A., Alvarez-Castro, C., Bellprat, O., Christiansen, B., Colfescu, I., Cowan, T., Doblas-Reyes, F., Eden, J., Hauser, M., Hegerl, G., Hempelmann, N., Klehmet, K., Lott, F., Nangini, C., Orth, R., Radanovics, S., Seneviratne, S.I., Oldenborgh, G.J.van, Stott, P., Tett, S., Wilcox, L., Yiou, P. %D 2019 %J Climate Dynamics %N 1-2 %P 1187-1210 %R doi:10.1007/s00382-018-4183-6 %T Evaluation of the HadGEM3-A simulations in view of detection and attribution of human influence on extreme events in Europe %U https://doi.org/10.1007/s00382-018-4183-6 1-2 %X A detailed analysis is carried out to assess the HadGEM3-A global atmospheric model skill in simulating extreme temperatures, precipitation and storm surges in Europe in the view of their attribution to human influence. The analysis is performed based on an ensemble of 15 atmospheric simulations forced with observed sea surface temperature of the 54 year period 1960–2013. These simulations, together with dual simulations without human influence in the forcing, are intended to be used in weather and climate event attribution. The analysis investigates the main processes leading to extreme events, including atmospheric circulation patterns, their links with temperature extremes, land–atmosphere and troposphere-stratosphere interactions. It also compares observed and simulated variability, trends and generalized extreme value theory parameters for temperature and precipitation. One of the most striking findings is the ability of the model to capture North-Atlantic atmospheric weather regimes as obtained from a cluster analysis of sea level pressure fields. The model also reproduces the main observed weather patterns responsible for temperature and precipitation extreme events. However, biases are found in many physical processes. Slightly excessive drying may be the cause of an overestimated summer interannual variability and too intense heat waves, especially in central/northern Europe. However, this does not seem to hinder proper simulation of summer temperature trends. Cold extremes appear well simulated, as well as the underlying blocking frequency and stratosphere-troposphere interactions. Extreme precipitation amounts are overestimated and too variable. The atmospheric conditions leading to storm surges were also examined in the Baltics region. There, simulated weather conditions appear not to be leading to strong enough storm surges, but winds were found in very good agreement with reanalyses. The performance in reproducing atmospheric weather patterns indicates that biases mainly originate from local and regional physical processes. This makes local bias adjustment meaningful for climate change attribution. %0 journal article %@ 1755-876X %A Staneva, J., Behrens, A., Gayer, G., Aouf, L. %D 2019 %J Journal of Operational Oceanography %N 3 %P 52-55 %R doi:10.1080/1755876X.2019.1633075 %T Synergy between CMEMS products and newly available data from SENTINEL %U https://doi.org/10.1080/1755876X.2019.1633075 3 %X This study explores the synergy between the CMEMS Monitoring and Forecasting Centres model products and the newly available satellite data. Working with these complementary sources of reliable information is useful not only for validation and assimilation purposes but also to explore in depth both the temporal and spatial scales of variability in European seas. The quality of the newly available Sentinel-3A (S3) data is assessed in comparison with data from Jason-3 (J3) at regional scales. The general performance of the wave products is very good and fairly similar compared to both satellite products. The assimilation of these satellite data in the global Monitoring and Forecasting Centres has indicated the skill of the system during storms generating high waves (Aouf ). The joined satellite and model analyses also demonstrates the capabilities of CMEMS as a whole, and the potential benefits of merging observational and modelled Copernicus products (Wiese et al. Behrens et al. ;). %0 journal article %@ 1463-5003 %A Stopa, J., Semedo, A., Staneva, J., Dobrynin, M., Behrens, A., Lemos, G. %D 2019 %J Ocean Modelling %P 18-29 %R doi:10.1016/j.ocemod.2018.12.002 %T A sampling technique to compare climate simulations with sparse satellite observations: Performance evaluation of a CMIP5 EC-Earth forced dynamical wave climate ensemble with altimeter observations %U https://doi.org/10.1016/j.ocemod.2018.12.002 %X Global climate simulations do not capture the exact time history, making it difficult to directly compare them with observations. In this study we simulate the sampling of altimeter observations from a seven-member wind and wave climate ensemble. This allows us to assess the skill of the climate simulations, relative to satellite observations instead of the typical approach which uses reanalysis or hindcast datasets as reference. Out of the sampling methods tested, we find that a systematic sampling technique performs the best. We then apply systematic sampling to wind fields from EC-Earth and wave fields generated using the wave model (WAM) to replicate the changing sampling of the satellite observations. Next we then quantitatively assess the climate simulations and find that the probability density functions (PDFs) computed from the EC-Earth wind speed samples match the shape of the PDFs obtained from the altimeter observations. EC-Earth consistently underestimates the wind speed with respect to the altimeter observations. Contrary to the wind speed underestimation, the wave simulations overestimate wave heights especially in the extra-tropics. The wind speed seasonality in EC-Earth is larger than the seasonality evaluated from altimeter wind observations while the opposite is true for the wave height seasonality; suggesting the wave physical parameterizations can be improved. We find that the wave height inter-annual variability of the modeled data is considerably less than the inter-annual variability evaluated from the altimeter observations; suggesting long-term climate variability is not well captured. Overall the wave ensemble captures the important features of the global wave climate. The methodology can be adapted to other climate simulations and observational datasets. %0 journal article %@ 1814-9324 %A Bothe, O., Wagner, S., Zorita, E. %D 2019 %J Climate of the Past %N 1 %P 307-334 %R doi:10.5194/cp-15-307-2019 %T Inconsistencies between observed, reconstructed, and simulated precipitation indices for England since the year 1650 CE %U https://doi.org/10.5194/cp-15-307-2019 1 %X Our results emphasize the complexity of changes in the hydroclimate during the most recent historical period and stress the necessity of a thorough understanding of the processes affecting forced and unforced precipitation variability. %0 journal article %@ 1463-5003 %A Wu, L., Staneva, J., Breivik, Ø., Rutgersson, A., Nurser, A., Clementi, E., Madec, G. %D 2019 %J Ocean Modelling %P 101405 %R doi:10.1016/j.ocemod.2019.101405 %T Wave effects on coastal upwelling and water level %U https://doi.org/10.1016/j.ocemod.2019.101405 %X Traditional atmosphere, ocean and wave models are run independently of each other. This means that the energy and momentum fluxes do not fully account for the impact of the oceanic wave field at the air-sea interface. In this study, the Stokes drift impact on mass and tracer advection, the Stokes-Coriolis forcing, and the sea-state-dependent momentum and energy fluxes are introduced into an ocean circulation model and tested for a domain covering the Baltic Sea and the North Sea. Sensitivity experiments are designed to investigate the influence on the simulation of storms and Baltic Sea upwelling. Inclusion of wave effects improves the model performance compared with the stand-alone circulation model in terms of sea level height, temperature and circulation. The direct sea-state-dependent momentum and turbulent kinetic energy fluxes prove to be of higher importance than the Stokes drift related effects investigated in this study (i.e., Stokes-Coriolis forcing and Stokes drift advection on tracers and on mass). The latter affects the mass and tracer advection but largely balances the influence of the Stokes-Coriolis forcing. The upwelling frequency changes by >10% along the Swedish coast when wave effects are included. In general, the strong (weak) upwelling probability is reduced (increased) when adding the wave effects. From the results, we conclude that inclusion of wave effects can be important for regional, high-resolution ocean models even on short time scales, suggesting that they should be introduced in operational ocean circulation models. However, care should be taken when introducing the Stokes-Coriolis forcing as it should be balanced by the Stokes drift in mass and tracer advection. %0 journal article %@ 2572-4525 %A Khider, D., Emile-Geay, J., McKay, N.P., Gil, Y., Garijo, D., Ratnakar, V., Alonso-Garcia, M., Bertrand, S., Bothe, O., Brewer, P., Bunn, A., Chevalier, M., Comas-Bru, L., Csank, A., Dassie, E., DeLong, K., Felis, T., Francus, P., Frappier, A., Gray, W., Goring, S., Jonkers, L., Kahle, M., Kaufman, D., Kehrwald, N.M., Martrat, B., McGregor, H., Richey, J., Schmittner, A., Scroxton, N., Thirumalai, K., Allen, K., Arnaud, F., Axford, Y., Barrows, T.T., Bazin, L., Pilaar Birch, S.E., Bradley, E., Bregy, J., Capron, E., Cartapanis, O., Chiang, H.-W., Cobb, K., Debret, M., Dommain, R., Du, J., Dyez, K., Emerick, S., Erb, M.P., Falster, G., Finsinger, W., Fortier, D., Gauthier, N., George, S., Grimm, E., Hertzberg, J., Hibbert, F., Hillman, A., Hobbs, W., Huber, M., Hughes, A.L.C., Jaccard, S., Ruan, J., Kienast, M., Konecky, B., Le Roux, G., Lyubchich, V., Novello, V.F., Olaka, L., Partin, J.W., Pearce, C., Phipps, S.J., Pignol, C., Piotrowska, N., Poli, M.-S., Prokopenko, A., Schwanck, F., Stepanek, C., Swann, G.E.A., Telford, R., Thomas, E., Thomas, Z., Truebe, S., Gunten, L.v., Waite, A., Weitzel, N., Wilhelm, B., Williams, J., Williams, J.J., Winstrup, M., Zhao, N., Zhou, Y. %D 2019 %J Paleoceanography and Paleoclimatology %N 10 %P 1570-1596 %R doi:10.1029/2019PA003632 %T PaCTS 1.0: A Crowdsourced Reporting Standard for Paleoclimate Data %U https://doi.org/10.1029/2019PA003632 10 %X The progress of science is tied to the standardization of measurements, instruments, and data. This is especially true in the Big Data age, where analyzing large data volumes critically hinges on the data being standardized. Accordingly, the lack of community‐sanctioned data standards in paleoclimatology has largely precluded the benefits of Big Data advances in the field. Building upon recent efforts to standardize the format and terminology of paleoclimate data, this article describes the Paleoclimate Community reporTing Standard (PaCTS), a crowdsourced reporting standard for such data. PaCTS captures which information should be included when reporting paleoclimate data, with the goal of maximizing the reuse value of paleoclimate datasets, particularly for synthesis work and comparison to climate model simulations. Initiated by the LinkedEarth project, the process to elicit a reporting standard involved an international workshop in 2016, various forms of digital community engagement over the next few years, and grassroots working groups. Participants in this process identified important properties across paleoclimate archives, in addition to the reporting of uncertainties and chronologies; they also identified archive‐specific properties and distinguished reporting standards for new vs. legacy datasets. This work shows that at least 135 respondents overwhelmingly support a drastic increase in the amount of metadata accompanying paleoclimate datasets. Since such goals are at odds with present practices, we discuss a transparent path towards implementing or revising these recommendations in the near future, using both bottom‐up and top‐down approaches. %0 journal article %@ %A Piracha, A., Sabia, R., Klockmann, M., Castaldo, L., Fernández, D. %D 2019 %J Frontiers in Marine Science %P 589 %R doi:10.3389/fmars.2019.00589 %T Satellite-Driven Estimates of Water Mass Formation and Their Spatio-Temporal Evolution %U https://doi.org/10.3389/fmars.2019.00589 %X We derive water mass transformation and formation rates using satellite-derived datasets of salinity, temperature and fluxes of heat and freshwater over the North Atlantic, North Pacific and Southern Ocean. The formation rates are expressed in three coordinate systems: (1) density, (2) temperature-salinity and (3) latitude-longitude. In the North Atlantic and North Pacific, peak formation occurs south of the western boundary current extensions during the winter months of the study period. In the Southern Ocean, wintertime peak formation occurs just north of the sub-Antarctic Front. The satellite-derived water mass properties and formation areas agree well with previous estimates from literature. The location of peak Mode Water formation varies slightly with time in all coordinate systems. We assess seasonal and inter-annual variability in all three basins from 2012 to 2014. We assess the impact of satellite uncertainties on final estimates of formation rates and areas with Monte-Carlo simulations. The simulations provide insights on the associated uncertainty of formation estimates. They also provide information on the geographic spread of the water mass formation area subject to the satellite errors. We find that the total uncertainty is dominated by the uncertainty in the sea surface salinity dataset. This stresses the need for frequent and increasingly accurate sea surface salinity data for reliable estimates of water mass formation rates and areas. Our study highlights the feasibility of providing satellite-based estimates of water mass formation rates and areas. The good spatio-temporal coverage of satellite data further adds to the utility of the approach. %0 journal article %@ 2169-9275 %A Stanev, E.V., Peneva, E., Chtirkova, B. %D 2019 %J Journal of Geophysical Research : Oceans %N 7 %P 4803-4819 %R doi:10.1029/2019JC015076 %T Climate change and regional ocean water mass disappearance: Case of the Black Sea %U https://doi.org/10.1029/2019JC015076 7 %X Data from profiling floats reveal that climate change in the Black Sea leads to the disappearance of specific water masses. The observed thermohaline change is possibly an amplified precursor of the changes to expect in the greater oceans. The warming trend in the cold intermediate layer (CIL) of ~0.05°C/yr was more than double the trend in previous decades, and its temperature approached that of the waters in the deeper layers (~9°C), which signified its disappearance. This evolution was due to the warmer winters over the last fourteen years. Intermittent major cold water formation events (only three during this period) could not sufficiently refill the CIL. A “density constriction” (minimum spread of density) was found at ~14.25 σt, and it separated two thermohaline regimes: temperature‐dominated above and salinity‐dominated beneath. Below this depth, the CIL is seen as a “corner" in the T‐S diagram at ~18 salinity and ~9°C, where the profiles make a curve. The variability in the T‐S relationships at given σt levels in the CIL revealed trends dominated by diapycnic mixing with deeper layers (the high‐salinity pool acts as a source of salt for the upper ocean). After 2010, salinity anomalies started to occur rhythmically with increasing amplitudes at the depths of the CIL. In the absence of a pronounced CIL in recent years, the relative role of salinity variability in the thermohaline state of the upper layers increased. Further trends and the plausibility of similar events in other similar environments are also addressed. %0 journal article %@ 0028-0836 %A Green, J.K., Seneviratne, S.I., Berg, A.M., Findell, K.L., Hagemann, S., Lawrence, D.M., Gentine, P. %D 2019 %J Nature %P 476-479 %R doi:10.1038/s41586-018-0848-x %T Large influence of soil moisture on long-term terrestrial carbon uptake %U https://doi.org/10.1038/s41586-018-0848-x %X Although the terrestrial biosphere absorbs about 25 per cent of anthropogenic carbon dioxide (CO2) emissions, the rate of land carbon uptake remains highly uncertain, leading to uncertainties in climate projections1,2. Understanding the factors that limit or drive land carbon storage is therefore important for improving climate predictions. One potential limiting factor for land carbon uptake is soil moisture, which can reduce gross primary production through ecosystem water stress3,4, cause vegetation mortality5 and further exacerbate climate extremes due to land–atmosphere feedbacks6. Previous work has explored the impact of soil-moisture availability on past carbon-flux variability3,7,8. However, the influence of soil-moisture variability and trends on the long-term carbon sink and the mechanisms responsible for associated carbon losses remain uncertain. Here we use the data output from four Earth system models9 from a series of experiments to analyse the responses of terrestrial net biome productivity to soil-moisture changes, and find that soil-moisture variability and trends induce large CO2 fluxes (about two to three gigatons of carbon per year; comparable with the land carbon sink itself1) throughout the twenty-first century. Subseasonal and interannual soil-moisture variability generate CO2 as a result of the nonlinear response of photosynthesis and net ecosystem exchange to soil-water availability and of the increased temperature and vapour pressure deficit caused by land–atmosphere interactions. Soil-moisture variability reduces the present land carbon sink, and its increase and drying trends in several regions are expected to reduce it further. Our results emphasize that the capacity of continents to act as a future carbon sink critically depends on the nonlinear response of carbon fluxes to soil moisture and on land–atmosphere interactions. This suggests that the increasing trend in carbon uptake rate may not be sustained past the middle of the century and could result in accelerated atmospheric CO2 growth. %0 journal article %@ 1812-0784 %A Schulz-Stellenfleth, J., Staneva, J. %D 2019 %J Ocean Science %N 2 %P 249-268 %R doi:10.5194/os-15-249-2019 %T A multi-collocation method for coastal zone observations with applications to Sentinel-3A altimeter wave height data %U https://doi.org/10.5194/os-15-249-2019 2 %X Different observation geometries of in situ data and altimeter tracks are furthermore analysed, considering 1-D and 2-D interpolation approaches. For example, the geometry of an altimeter track passing between two in situ wave instruments is considered with model data being available at the in situ locations. It is shown that for a sufficiently large sample, the errors of all data sources, as well as the error correlations of the model, can be estimated with the new method. %0 journal article %@ 1932-6203 %A Wirtz, K.W. %D 2019 %J PLoS One %N 2 %P 0212143 %R doi:10.1371/journal.pone.0212143 %T Physics or biology? Persistent chlorophyll accumulation in a shallow coastal sea explained by pathogens and carnivorous grazing %U https://doi.org/10.1371/journal.pone.0212143 2 %X One of the most striking patterns at the land–ocean interface is the massive increase of chlorophyll-a (CHL) from continental shelves towards the coast, a phenomenon that is classically linked to physical features. Here I propose that the coastal–offshore CHL gradient in a shallow sea has biological origins related to phytoplankton mortality that are neglected in state-of-the-art biogeochemical models. I integrate a trait-based ecosystem model into a modular coupling framework that is applied to the southern North Sea (SNS). The coupled model very well reproduces daily, seasonal and inter-annual (2000-2014) dynamics and meso-scale patterns in macronutrients, zooplankton biomass, and CHL as observed in situ and by remote sensors. Numerical experiments reveal that coast–offshore CHL gradients may predominantly arise from a trophic effect as resolved by an increase in carnivorous grazing towards shallow waters. This carnivory gradient reflects higher near-coast abundance of juvenile fish and benthic filter feeders. Furthermore, the temporal evolution of CHL can be much affected by viral infection as a fast-responding loss process at intermediate to high phytoplankton concentrations. Viral control in the model also prevents excessive and unrealistic blooms during late spring. Herbivores as often only ecological factor considered for explaining the spatio-temporal phytoplankton distribution are in this study supplemented by pathogens as well as pelagic and benthic carnivores as powerful agents, which are barely represented in current modeling but can mediate physical drivers of coastal ecosystems. %0 journal article %@ 2169-9275 %A Koul, V., Schrum, C., Duesterhus, A., Baehr, J. %D 2019 %J Journal of Geophysical Research : Oceans %N 3 %P 1807-1826 %R doi:10.1029/2018JC014738 %T Atlantic Inflow to the North Sea Modulated by the Subpolar Gyre in a Historical Simulation With MPI‐ESM %U https://doi.org/10.1029/2018JC014738 3 %X While the influence of the subpolar gyre (SPG) on thermohaline variability in the eastern North Atlantic is well documented, the extent and timescale of the influence of the SPG on North Sea is not well understood. This is primarily because earlier investigations on the causes of variability in the North Sea water properties mostly focused on the role of atmosphere and deployed regional models. Here using a historical simulation with the Max Planck Institute Earth System Model (MPI‐ESM), we investigate circulation and water mass variability in key regions, namely, the Rockall Trough and the Faroe‐Scotland Channel, which link the North Atlantic to the North Sea. We find that salinity covaries with advective lags in these three regions and that the northern North Sea salinity follows the Rockall Trough with a lag of 1 year. We show that recurring and persistent excursions of salinity anomalies into the northern North Sea are related to the SPG strength and not to the local acceleration of the inflow. Furthermore, we illustrate that the SPG signal is more pronounced in salinity than in temperature and that this simulated SPG signal has a period of 30–40 years. Overall, our study suggests that, at low frequency, water mass variability originating in the North Atlantic dominates changes in the North Sea water properties over those due to local wind‐driven volume transport. %0 journal article %@ 1674-9278 %A Storch, H.v., Chen, X., Pfau-Effinger, B., Bray, D., Ullmann, A. %D 2019 %J Advances in Climate Change Research %N 3 %P 158-164 %R doi:10.1016/j.accre.2019.04.001 %T Attitudes of young scholars in Qingdao and Hamburg about climate change and climate policy – The role of culture for the explanation of differences %U https://doi.org/10.1016/j.accre.2019.04.001 3 %X In order to evaluate these hypotheses, we have conducted a comparative survey among environmental science students in Qingdao (China) and Hamburg (Germany) about their attitudes towards climate change. The findings support our main hypotheses. The young scholars in Qingdao and Hamburg differ substantially in their views of the role of science in society and policymaking. Plausibly, these differences may mainly be explained with differences in the cultural ideas about the role of the state and of the civil society for the solution of environmental problems. Gradual differences in the share of young scholars who think that climate change has anthropogenic causes, may be explained with differences in the curriculum but also by cultural habits. This article makes a new contribution to the scientific debate by exploring the role of cultural differences for differences in the attitudes of young scholars in environmental science in connection with climate change and climate policy in different cultural contexts. %0 journal article %@ 1991-959X %A Daewel, U., Schrum, C., Macdonald, J. %D 2019 %J Geoscientific Model Development %N 5 %P 1765-1789 %R doi:10.5194/gmd-12-1765-2019 %T Towards end-to-end (E2E) modelling in a consistent NPZD-F modelling framework (ECOSMO E2E_v1.0): application to the North Sea and Baltic Sea %U https://doi.org/10.5194/gmd-12-1765-2019 5 %X We found that the model-simulated macrobenthos and fish spatial and seasonal pattern agree well with current system understanding. Considering a dynamic fish component in the ecosystem model resulted in slightly improved model performance with respect to representation of spatial and temporal variations in nutrients, changes in modelled plankton seasonality and nutrient profiles. Model sensitivity scenarios showed that changes in the zooplankton mortality parameter are transferred up and down the trophic chain with little attenuation of the signal, while major changes in fish mortality and in fish biomass cascade down the food chain. %0 journal article %@ 1054-3139 %A Samuelsen, A., Daewel, U., Wettre, C. %D 2019 %J ICES Journal of Marine Science : Journal du Conseil %N 6 %P 1902-1916 %R doi:10.1093/icesjms/fsz035 %T Risk of oil contamination of fish eggs and larvae under different oceanic and weather conditions %U https://doi.org/10.1093/icesjms/fsz035 6 %X An oil drift model is applied to determine the spread of oil spills from different locations along ship lanes off southern Norway every month for 20 years. These results are combined with results from an egg- and larvae drift model for Atlantic cod (Gadus morhua) to determine their risk of being impacted by oil. The number of eggs and larvae exposed to oil contamination is connected to environmental conditions. The highest risk of overlap between an oil spill and cod in early life stages occurs during March and April when the eggs and larvae concentrations are highest. Spills off the west coast pose a greater risk because of the ship lanes’ proximity to the spawning grounds, but there is large interannual variability. For some spill locations the interannual variability can be explained by variability in wind and ocean currents. Simultaneously occurring onshore transports lead to a high-risk situation because both oil and larvae are concentrated towards the coast. This study demonstrates how results from oil drift and biological models can be combined to estimate the risks of oil contamination for marine organisms, based on the location and timing of the oil spill, weather/ocean conditions, and knowledge of the organisms’ life cycle. %0 journal article %@ 2073-4433 %A Schaaf, B., Feser, F., Meinke, I. %D 2019 %J Atmosphere %N 5 %P 283 %R doi:10.3390/atmos10050283 %T Long-Term Atmospheric Changes in a Convection-Permitting Regional Climate Model Hindcast Simulation over Northern Germany and the German Bight %U https://doi.org/10.3390/atmos10050283 5 %X Long-term atmospheric changes are a result of complex interactions on various spatial scales. In this study, we examine the long-term variability of the most important meteorological variables in a convection-permitting regional climate model simulation. A consistent, gridded data set from 1948 to 2014 was computed using the regional climate model COSMO-CLM with a very high convection-permitting resolution at a grid distance of 2.8 km, for a region encompassing the German Bight and Northern Germany. This is one of the very first atmospheric model simulations with such high resolution, and covering several decades. Using a very high-resolution hindcast, this study aims to extend knowledge of the significance of regional details for long-term variability and multi-decadal trends of several meteorological variables such as wind, temperature, cloud cover, precipitation, and convective available potential energy (CAPE). This study demonstrates that most variables show merely large decadal variability and no long-term trends. The analysis shows that the most distinct and significant positive trends occur in temperature and in CAPE for annual mean values as well as for extreme events. No clear and no significant trend is detectable for the annual sum of precipitation and for extreme precipitation. However, spatial structures in the trends remain weak. %0 journal article %@ 1616-7341 %A Zhang, M., Storch, H.v., Chen, X., Wang, D., Li, D. %D 2019 %J Ocean Dynamics %N 8 %P 879-898 %R doi:10.1007/s10236-019-01282-2 %T Temporal and spatial statistics of travelling eddy variability in the South China Sea %U https://doi.org/10.1007/s10236-019-01282-2 8 %X The variability across decades of years of migrating eddy activities in the South China Sea (SCS) have not yet been documented. We employ a daily global eddy-resolving (0.1 degree) model product called STORM that covers a period of 1950-2010 to fill this gap. The frequency and pattern of eddy occurrence in the simulation is broadly consistent with satellite-based (AVISO) data. On average, annually 28 anticyclonic travelling eddy (AE) tracks and 54 cyclonic travelling eddy (CE) tracks with long travel lengths were derived from the discrete sea surface height anomaly fields of STORM. Eddy centers most frequently pass by the Luzon Strait and along the continental slope in the northern SCS to the Vietnam coast. The lifespans range from 6 days to 240 days for AEs and to 293 days for CEs, and the longest travel lengths are 1941 km and 1988 km, respectively. EOFs of the spatial fields of eddy diameter (ED), eddy intensity (EI) and eddy number (EN) show almost white eigenvalue spectra, when calculated on the model’s 0.1-degree grid, but when the data are coarsened to grids with 1-degree and 2-degree grid spacing, meaningful structures emerge. EI and ED are highly correlated on both seasonal and interannual time scales. In general, CEs are much more active than AEs, but the AEs with high intensities or large diameters are more frequent than similar CEs. The monthly ED, EI and EN exhibit annual cycles, which are, however, not very stable. The variabilities of annual means of ED, EI and EN is large at interannual time scales, little at interdecadal sales and exhibits hardly a trend. The sizes and intensities of eddies in the SCS are hardly connected to the ENSO-variability in the tropical Pacific. The EOFs, the weakness of the annual cycle stability and the absence of a correlation with ENSO, point to a massive presence of internal variability (as opposed to variability provoked by large-scale drivers). %0 journal article %@ 2071-1050 %A Bomhauer-Beins, L., de Guttry, C., Ratter, B.M.W. %D 2019 %J Sustainability %N 4 %P 1080 %R doi:10.3390/su11041080 %T When Culture Materializes: Societal Dynamics in Resilience of Social-Ecological Systems in the Case of Conch Management on Abaco, The Bahamas %U https://doi.org/10.3390/su11041080 4 %X The concept of resilience has greatly contributed to the scientific discussion on human–nature interactions by analysing the dynamics, relationships and feedbacks between society and the natural environment at different levels. In this paper, we analyse how culture and societal dynamics influence those connections and, at the same time, have the potential to eventually hinder or foster social-ecological resilience. In order to do so, we take the example of a natural element which is also a cultural icon: the Conch (pronounced ‘konk’). Conch is a marine mollusc with significant social and cultural value for the islands’ society of The Bahamas. In the last decade, a decline in several Conch stocks has been documented, calling for an urgent sustainable management strategy. Nevertheless, only little efforts are happening. This case study offers an innovative understanding of resilience by introducing an aspect which is too often overseen: the role of culture in shaping social-ecological resilience. In this case study, the role of culture proved to be crucial as the cultural significance and embeddedness of Conch has made the management process challenging. But at the same time, culture can be used as a positive impulse towards adaptive management and as a starting point for sustainability. When culture materializes, it affects not only societal dynamics but also the vulnerability and the resilience process of the entire social-ecological system. %0 journal article %@ 0077-8923 %A Ludwig, P., Gomez-Navarro, J.J., Pinto, J.G., Raible, C.C., Wagner, S., Zorita, E. %D 2019 %J Annals of the New York Academy of Sciences %N 1 %P 54-69 %R doi:10.1111/nyas.13865 %T Perspectives of regional paleoclimate modeling %U https://doi.org/10.1111/nyas.13865 1 %X Regional climate modeling bridges the gap between the coarse resolution of current global climate models and the regional‐to‐local scales, where the impacts of climate change are of primary interest. Here, we present a review of the added value of the regional climate modeling approach within the scope of paleoclimate research and discuss the current major challenges and perspectives. Two time periods serve as an example: the Holocene, including the Last Millennium, and the Last Glacial Maximum. Reviewing the existing literature reveals the benefits of regional paleo climate modeling, particularly over areas with complex terrain. However, this depends largely on the variable of interest, as the added value of regional modeling arises from a more realistic representation of physical processes and climate feedbacks compared to global climate models, and this affects different climate variables in various ways. In particular, hydrological processes have been shown to be better represented in regional models, and they can deliver more realistic meteorological data to drive ice sheet and glacier modeling. Thus, regional climate models provide a clear benefit to answer fundamental paleoclimate research questions and may be key to advance a meaningful joint interpretation of climate model and proxy data. %0 journal article %@ 0930-7575 %A Di Virgilio, G., Evans, J.P., Di Luca, A., Olsen, R., Argueso, D., Kala, J., Andrys, J., Hoffmann, P., Katzfey, J.J., Rockel, B. %D 2019 %J Climate Dynamics %P 2985-3005 %R doi:10.1007/s00382-019-04672-w %T Evaluating reanalysis-driven CORDEX regional climate models over Australia: model performance and errors %U https://doi.org/10.1007/s00382-019-04672-w %X The ability of regional climate models (RCMs) to accurately simulate current and future climate is increasingly important for impact assessment. This is the first evaluation of all reanalysis-driven RCMs within the CORDEX Australasia framework [four configurations of the Weather Forecasting and Research (WRF) model, and single configurations of COSMO-CLM (CCLM) and the Conformal-Cubic Atmospheric Model (CCAM)] to simulate the historical climate of Australia (1981–2010) at 50 km resolution. Simulations of near-surface maximum and minimum temperature and precipitation were compared with gridded observations at annual, seasonal, and daily time scales. The spatial extent, sign, and statistical significance of biases varied markedly between the RCMs. However, all RCMs showed widespread, statistically significant cold biases in maximum temperature which were the largest during winter. This bias exceeded − 5 K for some WRF configurations, and was the lowest for CCLM at ± 2 K. Most WRF configurations and CCAM simulated minimum temperatures more accurately than maximum temperatures, with biases in the range of ± 1.5 K. RCMs overestimated precipitation, especially over Australia’s populous eastern seaboard. Strong negative correlations between mean monthly biases in precipitation and maximum temperature suggest that the maximum temperature cold bias is linked to precipitation overestimation. This analysis shows that the CORDEX Australasia ensemble is a valuable dataset for future impact studies, but improving the representation of land surface processes, and subsequently of surface temperatures, will improve RCM performance. The varying RCM capabilities identified here serve as a foundation for the development of future regional climate projections and impact assessments for Australia. %0 journal article %@ 1715-2593 %A Petzold, J., Ratter, B.M.W. %D 2019 %J Island Studies Journal %N 1 %P 3-8 %R doi:10.24043/isj.77 %T More than just SIDS: local solutions for global problems on small islands %U https://doi.org/10.24043/isj.77 1 %X Small islands are often taken as poster children for climate change vulnerability, and their status as hotspots of climate change impacts has been widely acknowledged in the scientific literature. In many cases, however, individual studies as well as reviews and global assessments, generalise small islands as a whole—often with a strong focus on Small Island Developing States (SIDS)—and lack a thorough understanding of island specificity, relationality, and context dependency. Looking at small islands’ issues beyond SIDS implies the recognition of topics such as asymmetrical governance structures, archipelagic centre-periphery relationships, as well as intra- and inter-island movements in various types of island territories and geographies worldwide. This special thematic section of Island Studies Journal features contributions from the Atlantic, Indian, Pacific Ocean, and Caribbean dealing with the locally specific challenges and opportunities of adaptation to environmental and climate change. %0 journal article %@ 2190-4979 %A Zhao, C., Daewel, U., Schrum, C. %D 2019 %J Earth System Dynamics %N 2 %P 287-317 %R doi:10.5194/esd-10-287-2019 %T Tidal impacts on primary production in the North Sea %U https://doi.org/10.5194/esd-10-287-2019 2 %X This study highlights the importance of tides in controlling the spatial and temporal distributions of phytoplankton and other factors related to growth, such as nutrients and light availability. To quantify the responses of net primary production (NPP) to tidal forcing, we conducted scenario model simulations considering M2 and S2 tidal constituents using the physical–biogeochemical coupled model ECOSMO (ECOSystem MOdel). The results were analyzed with respect to a reference simulation without tidal forcing, with particular focus on the spatial scale of the tidally induced changes. Tidal forcing regulates the mixing–stratification processes in shelf seas such as the North Sea and hence also influences ecosystem dynamics. In principle, the results suggest three different response types with respect to primary production: (i) in southern shallow areas with strong tidal energy dissipation, tidal mixing dilutes phytoplankton concentrations in the upper water layers and thereby decreases NPP. Additionally, tides increase turbidity in near-coastal shallow areas, which has the potential to further hamper NPP. (ii) In the frontal region of the southern North Sea, which is a transition zone between stratified and mixed areas, tidal mixing infuses nutrients into the surface mixed layer and resolves summer nutrient depletion, thus sustaining the NPP during the summer season after spring bloom nutrient depletion. (iii) In the northern North Sea, the NPP response to tidal forcing is limited. Additionally, our simulations indicate that spring bloom phenology is impacted by tidal forcing, leading to a later onset of the spring bloom in large parts of the North Sea and to generally higher spring bloom peak phytoplankton biomasses. By testing the related changes in stratification, light conditions and grazing pressure, we found that all three factors potentially contribute to the change in spring bloom phenology with clear local differences. Finally, we also analyzed the impact of the spring–neap tidal cycle on NPP. The annual mean impact of spring–neap tidal forcing on NPP is limited. However, locally, we found substantial differences in NPP either in phase or anti-phase with the spring–neap tidal cycle. These differences could be attributed to locally different dominant factors such as light or nutrient availability during spring tides. In general, we conclude that in shallow shelf seas such as the North Sea, intensified vertical mixing induced by tidal forcing could either promote NPP by counteracting nutrient depletion or hinder NPP by deteriorating the light environment because of the resuspension and mixing of suspended matter into the euphotic zone. %0 journal article %@ 2296-7745 %A Gommenginger, C., Chapron, B., Hogg, A., Buckingham, C., Fox-Kemper, B., Eriksson, L., Soulat, F., Ubelmann, C., Ocampo-Torres, F., Nardelli, B., Griffin, D., Lopez-Dekker, P., Knudsen, P., Andersen, O., Stenseng,L., Stapleton, N., Perrie, W., Violante-Carvalho, N., Schulz-Stellenfleth, J., Woolf, D., Isern-Fontanet, J., Ardhuin, F., Klein, P., Mouche, A., Pascual, A., Capet, X., Hauser, D., Stoffelen, A., Morrow, R., Aouf, L., Breivik, Ø., Fu, L., Johannessen, J.A., Aksenov, Y., Bricheno, L., Hirschi, J., Martin, A.C.H., Martin, A.P., Nurser, G., Polton, J., Wolf, J., Johnsen, H., Soloviev, A., Jacobs, G.A., Collard, F., Groom, S., Kudryavtsev, V., Wilkin, J., Navarro, V., Babanin, A., Martin, M., Siddorn, J., Saulter, A., Rippeth, T., Emery, B., Maximenko, N., Romeiser, R., Graber, H., Alvera-Azcarate, A., Hughes, C. W., Vandemark, D., Silva, J. da, Leeuwen, P.J. Van, Naveira-Garabato, A., Gemmrich, J., Mahadevan, A., Marquez, J., Munro, Y., Doody, S., Burbidge G. %D 2019 %J Frontiers in Marine Science %P 457 %R doi:10.3389/fmars.2019.00457 %T SEASTAR: A Mission to Study Ocean Submesoscale Dynamics and Small-Scale Atmosphere-Ocean Processes in Coastal, Shelf and Polar Seas %U https://doi.org/10.3389/fmars.2019.00457 %X High-resolution satellite images of ocean color and sea surface temperature reveal an abundance of ocean fronts, vortices and filaments at scales below 10 km but measurements of ocean surface dynamics at these scales are rare. There is increasing recognition of the role played by small scale ocean processes in ocean-atmosphere coupling, upper-ocean mixing and ocean vertical transports, with advanced numerical models and in situ observations highlighting fundamental changes in dynamics when scales reach 1 km. Numerous scientific publications highlight the global impact of small oceanic scales on marine ecosystems, operational forecasts and long-term climate projections through strong ageostrophic circulations, large vertical ocean velocities and mixed layer re-stratification. Small-scale processes particularly dominate in coastal, shelf and polar seas where they mediate important exchanges between land, ocean, atmosphere and the cryosphere, e.g., freshwater, pollutants. As numerical models continue to evolve toward finer spatial resolution and increasingly complex coupled atmosphere-wave-ice-ocean systems, modern observing capability lags behind, unable to deliver the high-resolution synoptic measurements of total currents, wind vectors and waves needed to advance understanding, develop better parameterizations and improve model validations, forecasts and projections. SEASTAR is a satellite mission concept that proposes to directly address this critical observational gap with synoptic two-dimensional imaging of total ocean surface current vectors and wind vectors at 1 km resolution and coincident directional wave spectra. Based on major recent advances in squinted along-track Synthetic Aperture Radar interferometry, SEASTAR is an innovative, mature concept with unique demonstrated capabilities, seeking to proceed toward spaceborne implementation within Europe and beyond. %0 journal article %@ 0964-5691 %A Gee, K., Blazauskas, N., Dahl, K., Goeke, C., Hassler, B., Kannen, A., Leposa, N., Morf, A., Strand, H., Weig, B., Zaucha, J. %D 2019 %J Ocean and Coastal Management %P 104834 %R doi:10.1016/j.ocecoaman.2019.104834 %T Can tools contribute to integration in MSP? A comparative review of selected tools and approaches %U https://doi.org/10.1016/j.ocecoaman.2019.104834 %X The role of tools and approaches is currently much debated in maritime spatial planning (MSP). Past evaluation has mainly concentrated on decision support tools and the tangible outputs these can provide for MSP, but little attention has so far been been given to the soft or indirect benefits tool use can have in MSP. This paper assesses the potential benefits of tool use in the context of four common integration challenges in MSP. Drawing on case study material from the Baltic Sea region, the paper reviews the potential contribution of five selected tools and approaches to multi-level and transboundary, policy and sector, stakeholder and knowledge integration. Specific end points are defined for each integration challenge, including general desired outcomes of integrated MSP processes as a template for assessment. Our review shows that the selected tools play different roles in moving towards the various end points of MSP integration. There is an important difference between the potential of each tool, or its inherent capacity, and how it is applied, e.g. in a participative or non-participative setting. Another lesson is that some integration benefits can be achieved by the tools alone, while others – often secondary benefits - depend on how the outcomes of tool use are taken up by the subsequent MSP process. Although the nature of a tool does restrict its potential contribution to MSP integration challenges, the secondary “soft” benefits that can be achieved through certain styles of application and good links to the MSP process can add important integration benefits up and beyond the tool itself. The results presented here may also be relevant to other types of spatial planning and conservation management. %0 journal article %@ 2169-8961 %A Zhang, W., Wirtz, K., Daewel, U., Wrede, A., Kroencke, I., Kuhn, G., Neumann, A., Meyer, J., Ma, M., Schrum, C. %D 2019 %J Journal of Geophysical Research : Biogeosciences %N 6 %P 1446-1471 %R doi:10.1029/2019JG005109 %T The Budget of Macrobenthic Reworked Organic Carbon: A Modeling Case Study of the North Sea %U https://doi.org/10.1029/2019JG005109 6 %X The importance of macrobenthos in benthic‐pelagic coupling and early diagenesis of organic carbon has long been recognized but has not been quantified at a regional scale. By using the southern North Sea as an exemplary area we present a modeling attempt to quantify the budget of total organic carbon (TOC) reworked by macrobenthos in seafloor surface sediments. Vertical profiles in sediments collected in the field indicate a significant but nonlinear correlation between TOC and macrobenthic biomass. A mechanistic model is used to resolve the bidirectional interaction between TOC and macrobenthos. A novelty of this model is that bioturbation is resolved dynamically depending on variations in local food resource and macrobenthic biomass. The model is coupled to 3‐D hydrodynamic‐biogeochemical simulations to hindcast the mutual dependence between sedimentary TOC and macrobenthos from 1948 to 2015. Agreement with field data reveals a satisfactory model performance. Our simulations show that the preservation of TOC in the North Sea sediments is determined not only by pelagic conditions (hydrodynamic regime and primary production) but also by the vertical distribution of TOC, bioturbation intensity, and the vertical positioning of macrobenthos. Macrobenthos annually ingest 20–35% and in addition vertically diffuse 11–22% of the total budget of TOC in the uppermost 30‐cm sediments in the southern North Sea. This result indicates a central role of benthic animals in modulating the organic carbon cycling at the sediment‐water interface of continental margins. %0 journal article %@ 1866-3508 %A Bothe, O., Wagner, S., Zorita, E. %D 2019 %J Earth System Science Data %N 3 %P 1129-1152 %R doi:10.5194/essd-11-1129-2019 %T Simple noise estimates and pseudoproxies for the last 21 000 years %U https://doi.org/10.5194/essd-11-1129-2019 3 %X Climate reconstructions are means to extract the signal from uncertain paleo-observations, so-called proxies. It is essential to evaluate these reconstructions to understand and quantify their uncertainties. Similarly, comparing climate simulations and proxies requires approaches to bridge the temporal and spatial differences between both and to address their specific uncertainties. One way to achieve these two goals is so-called pseudoproxies. These are surrogate proxy records within the virtual reality of a climate simulation. They in turn depend on an understanding of the uncertainties of the real proxies including the noise characteristics disturbing the original environmental signal. Common pseudoproxy approaches so far concentrate on data with high temporal resolution over the last approximately 2000 years. Here we provide a simple but flexible noise model forpotentiallylow-resolutionsedimentaryclimateproxiesfortemperatureonmillennialtimescales,thecodefor calculating a set of pseudoproxies from a simulation, and one example of pseudoproxies. The noise model considers the influence of other environmental variables, a dependence on the climate state, a bias due to changing seasonality, modifications of the archive (for example bioturbation), potential sampling variability, and a measurement error. Model, code, and data allow us to develop new ways of comparing simulation data with proxies onlongtimescales. %0 journal article %@ 1400-0350 %A Evadzi, P.I.K., Zorita, E., Huenicke, B. %D 2019 %J Journal of Coastal Conservation %N 4 %P 759-771 %R doi:10.1007/s11852-019-00704-z %T West African sea level variability under a changing climate - What can we learn from the observational period? %U https://doi.org/10.1007/s11852-019-00704-z 4 %X This study focuses on mean sea-level variability at the West African coast in the observational period (1993–2013) and its offshore waters, investigating its decadal variability, long-term trends and the large-scale climate patterns that are connected to its variability. To achieve this objective, statistically analyses is performed on several available data sets: sea-level data from tide gauges (Takoradi, Tema and Forcados), satellite altimetry (combined TOPEX/Poseidon, Jason-1 and Jason-2/OSTM), gridded sea-level reconstruction (Church et al., J Clim 17(13):2609–2625, 2004), meteorological reanalysis (NCEP), a high-resolution ocean model simulation driven by this meteorological reanalysis, and, observational data sets (The Hadley Centre Global Sea Ice and Sea Surface Temperature (HadISST1), and the Atlantic Multi-decadal Oscillation (AMO) index). Ghana is the only country along the West African coast with two relatively long sea-level records available (Takoradi and Tema), but with data quality concerns (Woodworth et. al., Afr J Mar Sci 29(3):321–330, 2007). Attempts are made to combine these two records, which cover different but overlapping periods, to construct a regional sea-level curve for Ghana (1929–1981) that may be regionally representative. A physical connection is identified between the AMO, sea-surface temperature and sea level in the Gulf of Guinea and mean sea-level trends and variability of the West African coast. It has been found that a stronger AMO is connected with higher mean sea-level in the Tropical Atlantic and in particular also at the Gulf of Guinea sea-level. This connection may explain the multidecadal variability of sea-level there, and in particular the negative trends between 1955 and 1975 and the positive trends thereafter. In addition, warmer sea surface temperatures in the Gulf of Guinea are also connected with higher sea-level, although a simple estimation based on reasonable assumptions of the thermal expansion of the water column is not sufficient to explain the connection between sea-surface-temperature and sea-level. More detailed modelling studies will be needed to explain this link. Although this study provides useful information for adaption strategies in Ghana, the research is unable to provide sea-level information between the years 1981 and 1993 because of lack of data. %0 journal article %@ 1461-0248 %A Chen, B., Smith, S.L., Wirtz, K.W. %D 2019 %J Ecology Letters %N 1 %P 56-66 %R doi:10.1111/ele.13167 %T Effect of phytoplankton size diversity on primary productivity in the North Pacific: trait distributions under environmental variability %U https://doi.org/10.1111/ele.13167 1 %X While most biodiversity and ecosystem functioning (BEF) studies have found positive effects of species richness on productivity, it remain unclear whether similar patterns hold for marine phytoplankton with high local richness. We use the continuous trait‐based modelling approach, which assumes infinite richness and represents diversity in terms of the variance of the size distribution, to investigate the effects of phytoplankton size diversity on productivity in a three‐dimensional ocean circulation model driven by realistic physics forcing. We find a slightly negative effect of size diversity on primary production, which we attribute to several factors including functional trait‐environment interactions, flexible stoichiometry and the saturation of productivity at low diversity levels. The benefits of trait optimisation, whereby narrow size distributions enhance productivity under relatively stable conditions, tend to dominate over those of adaptive capacity, whereby greater diversity enhances the ability of the community to respond to environmental variability. %0 journal article %@ 0894-8755 %A Krueger, O., Feser, F., Weisse, R %D 2019 %J Journal of Climate %N 6 %P 1919-1931 %R doi:10.1175/JCLI-D-18-0505.1 %T Northeast Atlantic Storm Activity and Its Uncertainty from the Late Nineteenth to the Twenty-First Century %U https://doi.org/10.1175/JCLI-D-18-0505.1 6 %X Geostrophic wind speeds calculated from mean sea level pressure readings are used to derive time series of northeast Atlantic storminess. The technique of geostrophic wind speed triangles provides relatively homogeneous long-term storm activity data and is thus suited for statistical analyses. This study makes use of historical air pressure data available from the International Surface Pressure Databank (ISPD) complemented with data from the Danish and Norwegian Meteorological Institutes. For the first time the time series of northeast Atlantic storminess is extended until the most recent year available, i. e. 2016. A multi-decadal increasing trend in storm activity starting in the mid-1960s until the 1990s, whose high storminess levels are comparable to those found in the late 19th century, initiated debate whether this would already be a sign of climate change. This study confirms that long-term storminess levels have returned to average values in recent years and that the multidecadal increase is part of an extended interdecadal oscillation. In addition, new storm activity uncertainty estimates were developed and novel insights into the connection with the North Atlantic Oscillation (NAO) are provided. %0 journal article %@ 0278-4343 %A Zhao, C., Maerz, J., Hofmeister, R., Röttgers, R., Wirtz, K., Riethmüller, R., Schrum, C. %D 2019 %J Continental Shelf Research %P 127-146 %R doi:10.1016/j.csr.2019.01.012 %T Characterizing the vertical distribution of chlorophyll a in the German Bight %U https://doi.org/10.1016/j.csr.2019.01.012 %X Coastal and shelf seas display strong variability in the horizontal and vertical distributions of chlorophyll a (CHL). Detailed data are required to identify the processes that drive the observed spatio-temporal dynamics. A high-resolution, vertically resolved transect data set for biogeochemical and physical properties was collected in the inner German Bight (GB) from 2009 to 2011 on a seasonal basis. We used fluorescence as an indicator for phytoplankton biomass via the CHL concentrations. We classified profiles into different types by evaluating the heterogeneity of CHL vertical distribution and identifying vertical location (upper mixed layer, subsurface layer, bottom mixed layer of water column) of high CHL concentration in each profile. We analyzed the spatio-temporal occurrences of the different CHL vertical distribution types in the context of the hydrodynamic environment. More than half (68.7%) of all profiles showed vertically homogeneous CHL distributions. A smaller subset (3.2%) of all profiles showed subsurface CHL maximum layers (SCMLs) in the vicinity of the pycnocline, co-varying with strongly stratified conditions in deeper water. Profiles with highest concentration of CHL in the upper part of the water column (HCU) were observed in 11.5% of all profiles. Profiles with highest concentrations of CHL in the lower part of the water column (HCL) comprised 16.6% of all profiles. HCL profiles were extensively observed during the decay phase of the spring bloom and were associated with resuspension and erosion from pre-existing SCMLs, which could be driven by tide; photosynthetic activity below the pycnocline could also contribute. Under moderate weather conditions, tidal currents were the main driver of resuspension. This study highlighted the occurrence of SCMLs and HCL patterns in vertical CHL profiles in shallow shelf seas, such as the GB. %0 journal article %@ 2073-4433 %A Wiese, A., Stanev, E., Koch, W., Behrens, A., Geyer, B., Staneva, J. %D 2019 %J Atmosphere %N 7 %P 386 %R doi:10.3390/atmos10070386 %T The Impact of the Two-Way Coupling between Wind Wave and Atmospheric Models on the Lower Atmosphere over the North Sea %U https://doi.org/10.3390/atmos10070386 7 %X The effects of coupling between the atmospheric model of the Consortium for Small-Scale Modelling-Climate Limited-area Modelling (CCLM) and the wind wave model (WAM) on the lower atmosphere within the North Sea area are studied. Due to the two-way coupling between the models, the influences of wind waves and the atmosphere on each other can be determined. This two-way coupling between these models is enabled through the introduction of wave-induced drag into CCLM and updated winds into WAM. As a result of wave-induced drag, different atmospheric parameters are either directly or indirectly influenced by the wave conditions. The largest differences between the coupled and reference model simulation are found during storm events as well as in areas of steep gradients in the mean sea level pressure, wind speed or temperature. In the two-way coupled simulation, the position and strength of these gradients vary, compared to the reference simulation, leading to differences that spread throughout the entire planetary boundary layer and outside the coupled model area, thereby influencing the atmosphere over land and ocean, although not coupled to the wave model. Ultimately, the results of both model simulations are assessed against in situ and satellite measurements, with a better general performance of the two-way coupled simulation with respect to the observations. %0 journal article %@ 0278-4343 %A Stanev, E.V., Jacob, B., Pein, J. %D 2019 %J Continental Shelf Research %P 48-65 %R doi:10.1016/j.csr.2019.01.001 %T German Bight estuaries: An inter-comparison on the basis of numerical modeling %U https://doi.org/10.1016/j.csr.2019.01.001 %X The Semi-implicit Cross-scale Hydroscience Integrated System Model (SCHISM), which is an unstructured-grid model, was coupled with a 3D sediment model and established for the German Bight and its estuaries. The horizontal resolution of the model ranges from ~10 m in the estuaries to ~400 m in most of the open sea. Validation against tidal gauge data, fixed station data, and FerryBox data demonstrated that the model adequately simulated tidal dynamics in the entire area as well as the salinity fronts and estuarine turbidity maxima in the Ems, Weser and Elbe estuaries. Comparisons of model output with that of experiments with constant density allowed to estimate the role of density control, which appeared to be strongest in the landward reaches of salinity front. The increase of tidal range caused by density effects was most prominent in the Weser and Elbe estuaries, and relatively small in the Ems, where the runoff was also small. The magnitude of the density effect on the sea level oscillations was comparable to that of the M4 tide amplitude, demonstrating its importance in shaping the tidal asymmetry in the estuaries. Density effects not only reduced the dissipation of tidal energy; density stratification suppressed also the resuspension of sediment and contributed to a displacement of the position of the estuarine turbidity maximum upstream compared to the case of an homogeneous estuary. In the case of hyper-turbid Ems Estuary, density effects on stratification caused by high sediment concentrations resulted in a suppression of turbulence and further increase of concentration of suspended matter at the bottom. Although the three estuaries, which are only ~100 km apart, were driven by similar tidal and atmospheric forcings, they exhibited different extensions of both fronts and vertical stratification, mainly due to different river runoff conditions. At intra-tidal time scales, the dependencies between sea surface height and sea surface salinity varied considerably from estuary to estuary, and the largest flood asymmetry appeared in the Elbe Estuary. Wind acted as the dominant factor driving the longer-term estuarine variability; the correlation between zonal wind magnitude and sea surface height appeared to be very strong. The simulated suspended particulate matter dynamics and position of the estuarine turbidity maxima (ETM) were in agreement with observations. Secondary ETM appeared at different locations depending on the grain size, providing an illustration of sediment sorting. %0 journal article %@ 0027-8424 %A Zhou, S., Williams, A.P., Berg, A.M., Cook, B.I., Zhang, Y., Hagemann, S., Lorenz, R., Seneviratne, S.I., Gentine, P. %D 2019 %J Proceedings of the National Academy of Sciences of the United States of America: PNAS %N 38 %P 18848-18853 %R doi:10.1073/pnas.1904955116 %T Land–atmosphere feedbacks exacerbate concurrent soil drought and atmospheric aridity %U https://doi.org/10.1073/pnas.1904955116 38 %X Compound extremes such as cooccurring soil drought (low soil moisture) and atmospheric aridity (high vapor pressure deficit) can be disastrous for natural and societal systems. Soil drought and atmospheric aridity are 2 main physiological stressors driving widespread vegetation mortality and reduced terrestrial carbon uptake. Here, we empirically demonstrate that strong negative coupling between soil moisture and vapor pressure deficit occurs globally, indicating high probability of cooccurring soil drought and atmospheric aridity. Using the Global Land Atmosphere Coupling Experiment (GLACE)-CMIP5 experiment, we further show that concurrent soil drought and atmospheric aridity are greatly exacerbated by land–atmosphere feedbacks. The feedback of soil drought on the atmosphere is largely responsible for enabling atmospheric aridity extremes. In addition, the soil moisture–precipitation feedback acts to amplify precipitation and soil moisture deficits in most regions. CMIP5 models further show that the frequency of concurrent soil drought and atmospheric aridity enhanced by land–atmosphere feedbacks is projected to increase in the 21st century. Importantly, land–atmosphere feedbacks will greatly increase the intensity of both soil drought and atmospheric aridity beyond that expected from changes in mean climate alone. %0 journal article %@ 2296-7745 %A Stanev, E.V., Ricker, M. %D 2019 %J Frontiers in Marine Science %P 660 %R doi:10.3389/fmars.2019.00660 %T The Fate of Marine Litter in Semi-Enclosed Seas: A Case Study of the Black Sea %U https://doi.org/10.3389/fmars.2019.00660 %X The accumulation patterns of floating marine litter (FML) in the Black Sea and the stranding locations on coasts are studied by performing dedicated Lagrangian simulations using freely available ocean current and Stokes drift data from operational models. The low FML concentrations in the eastern and northern areas and the high concentrations along the western and southern coasts are due to the dominant northerlies and resulting Ekman and Stokes drift. No pronounced FML accumulation zones resembling the Great Pacific Garbage Patch are observed at time scales from months to a year. The ratio of circulation intensity (measured by the sea level slope) to the rate of the temporal variability of sea level determines whether FML will compact. This ratio is low in the Black Sea, which is prohibitive for FML accumulation. It is demonstrated that the strong temporal variability of the velocity field (ageostrophic motion) acts as a mixing mechanism that opposes another ageostrophic constituent of the velocity field (spatial variability in sea level slope, or frontogenesis), the latter promoting the accumulation of particles. The conclusion is that not all ageostrophic ocean processes lead to clustering. The short characteristic stranding time of ∼20 days in this small and almost enclosed basin explains the large variability in the total amount of FML and the low FML concentration in the open ocean. The predominant stranding areas are determined by the cyclonic general circulation. The simulated distribution of stranded objects is supported by available coastal and near-coastal observations. It is shown that the areas that were the most at risk extend from the Kerch Strait to the western coast. %0 journal article %@ 0003-0007 %A Weitzel, N., Wagner, S., Sjolte, J., Klockmann, M., Bothe, O., Andres, H., Tarasov, L., Rehfeld, K., Zorita, E., Widmann, M., Sommer, P., Schaedler, G., Ludwig, P., Kapp, F., Jonkers, L., Garcia_Pintado, J., Fuhrmann, F., Dolman, A., Dallmeyer, A., Bruecher, T. %D 2019 %J Bulletin of the American Meteorological Society %N 1 %P ES1-ES4 %R doi:10.1175/BAMS-D-18-0169.1 %T Diving into the Past: A Paleo Data–Model Comparison Workshop on the Late Glacial and Holocene %U https://doi.org/10.1175/BAMS-D-18-0169.1 1 %X Understanding changes in the climate of the late Pleistocene and the Holocene has long been a research topic. Studies rely on different sources of information, ranging from terrestrial and marine archives to a hierarchy of climate modeling activities. In contrast to the climate of the last millennium, novel approaches are necessary to bridge the different temporal and spatial representations of the various archives and the climate models, and to achieve a robust understanding of climate variability and climate processes on centennial-to-millennial time scales. %0 journal article %@ 0018-8158 %A Slavik, K., Lemmen, C., Zhang, W., Kerimoglu, O., Klingbeil, K., Wirtz, K.W. %D 2019 %J Hydrobiologia %N 1 %P 35-53 %R doi:10.1007/s10750-018-3653-5 %T The large-scale impact of offshore wind farm structures on pelagic primary productivity in the southern North Sea %U https://doi.org/10.1007/s10750-018-3653-5 1 %X The increasing demand for renewable energy is projected to result in a 40-fold increase in offshore wind electricity in the European Union by 2030. Despite a great number of local impact studies for selected marine populations, the regional ecosystem impacts of offshore wind farm (OWF) structures are not yet well assessed nor understood. Our study investigates whether the accumulation of epifauna, dominated by the filter feeder Mytilus edulis (blue mussel), on turbine structures affects pelagic primary productivity and ecosystem functioning in the southern North Sea. We estimate the anthropogenically increased potential distribution based on the current projections of turbine locations and reported patterns of M. edulis settlement. This distribution is integrated through the Modular Coupling System for Shelves and Coasts to state-of-the-art hydrodynamic and ecosystem models. Our simulations reveal non-negligible potential changes in regional annual primary productivity of up to 8% within the OWF area, and induced maximal increases of the same magnitude in daily productivity also far from the wind farms. Our setup and modular coupling are effective tools for system scale studies of other environmental changes arising from large-scale offshore wind farming such as ocean physics and distributions of pelagic top predators. %0 journal article %@ 2169-897X %A Hirsch, A.L., Evans, J.P., Di Virgillio, G., Perkins-Kirkpatrick, S.E., Argueso, D., Pitman, A.J., Carouge, C.C., Kala, J., Andrys, J., Petrelli, P., Rockel, B. %D 2019 %J Journal of Geophysical Research : Atmospheres %N 24 %P 13625-13647 %R doi:10.1029/2019JD030665 %T Amplification of Australian Heatwaves via Local Land‐Atmosphere Coupling %U https://doi.org/10.1029/2019JD030665 24 %X Antecedent land surface conditions play a role in the amplification of temperature anomalies experienced during heatwaves by modifying the local partitioning of available energy between sensible and latent heating. Most existing analyses of heatwave amplification from soil moisture anomalies have focused on exceptionally rare events and consider seasonal scale timescales. However, it is not known how much the daily evolution of land surface conditions, both before and during a heatwave, contributes to the intensity and frequency of these extremes. We examine how the daily evolution of land surface conditions preceding a heatwave event contributes to heatwave intensity. We also diagnose why the land surface contribution to Australian heatwaves is not homogeneous due to spatiotemporal variations in land‐atmosphere coupling. We identify two coupling regimes: a land‐driven regime where surface temperatures are sensitive to local variations in sensible heating and an atmosphere‐driven regime where this is not the case. Northern Australia is consistently strongly coupled, where antecedent soil moisture conditions can influence temperature anomalies up to day 4 of a heatwave. For southern Australia, heatwave temperature anomalies are not influenced by antecedent soil moisture conditions due to an atmosphere‐driven coupling regime. Therefore, antecedent land surface conditions have a role in increasing the temperature anomalies experienced during a heatwave only over regions with strong land‐driven coupling. The timescales over which antecedent land surface conditions contribute to Australian heatwaves also vary regionally. Overall, the spatiotemporal variations of land‐atmosphere interactions help determine where and when antecedent land surface conditions contribute to Australian heat extremes. %0 journal article %@ 2072-4292 %A Zhang, H., Liu, X., Wu, R., Liu, F., Yu, L., Shang, X., Qi, Y., Wang, Y., Song, X., Xie, X., Yang, C., Tian, D., Zhang, W. %D 2019 %J Remote Sensing %N 20 %P 2360 %R doi:10.3390/rs11202360 %T Ocean Response to Successive Typhoons Sarika and Haima (2016) Based on Data Acquired via Multiple Satellites and Moored Array %U https://doi.org/10.3390/rs11202360 20 %X Tropical cyclones (TCs) are natural disasters for coastal regions. TCs with maximum wind speeds higher than 32.7 m/s in the north-western Pacific are referred to as typhoons. Typhoons Sarika and Haima successively passed our moored observation array in the northern South China Sea in 2016. Based on the satellite data, the winds (clouds and rainfall) biased to the right (left) sides of the typhoon tracks. Sarika and Haima cooled the sea surface similar to 4 and similar to 2 degrees C and increased the salinity similar to 1.2 and similar to 0.6 psu, respectively. The maximum sea surface cooling occurred nearly one day after the two typhoons. Station 2 (S2) was on left side of Sarika's track and right side of Haima's track, which is studied because its data was complete. Strong near-inertial currents from the ocean surface toward the bottom were generated at S2, with a maximum mixed-layer speed of similar to 80 cm/s. The current spectrum also shows weak signal at twice the inertial frequency (2f). Sarika deepened the mixed layer, cooled the sea surface, but warmed the subsurface by similar to 1 degrees C. Haima subsequently pushed the subsurface warming anomaly into deeper ocean, causing a temperature increase of similar to 1.8 degrees C therein. Sarika and Haima successively increased the heat content anomaly upper than 160 m at S2 to similar to 50 and similar to 100 m degrees C, respectively. Model simulation of the two typhoons shows that mixing and horizontal advection caused surface ocean cooling, mixing and downwelling caused subsurface warming, while downwelling warmed the deeper ocean. It indicates that Sarika and Haima sequentially modulated warm water into deeper ocean and influenced internal ocean heat budget. Upper ocean salinity response was similar to temperature, except that rainfall refreshed sea surface and caused a successive salinity decrease of similar to 0.03 and similar to 0.1 psu during the two typhoons, changing the positive subsurface salinity anomaly to negative %0 journal article %@ 0016-7460 %A Ratter, B.M.W., Schaper, J. %D 2019 %J Geographische Rundschau %N 9 %P 28-33 %T Risiko-Management in der Badewanne %U 9 %X Ostfriesland liegt in großen Teilen unter dem Meeresspiegel und ist insbesondere bei Sturmflut durch Wasser von allen Seiten bedroht. Im Kontext des Klimawandels verschaerft sich diese Gefaehrdungslage und stellt Kuestenschutz, Deich- und Entwaesserungsverbaende vor wachsende Herausforderungen. Der Beitrag gibt einen Einblick in die Risikolandschaft und zeigt, welchen Herausforderungen sich ein an die vielfaeltigen Bedrohungen angepasstes Risiko-Management heute und in Zukunft stellen muss. %0 journal article %@ 0025-3227 %A Zhang, W., Didenkulova, I., Kurkina, O., Cui, Y., Haberkern, J., Aepfler, R., Santos, A., Zhang, H., Hanebuth, T. %D 2019 %J Marine Geology %P 15-30 %R doi:10.1016/j.margeo.2018.12.008 %T Internal solitary waves control offshore extension of mud depocenters on the NW Iberian shelf %U https://doi.org/10.1016/j.margeo.2018.12.008 %X Hydrodynamic conditions and near-bottom sediment transport on the NW Iberian shelf associated with a 5-day storm in September 2014 were monitored. During the post-storm relaxation period, active bottom sediment transport by internal solitary waves (ISWs) on a mid-shelf mud depocenter, located in between 110 and 130 m water depth (WD), was observed. To explore the potential of internal waves in sediment transport and its link to development of mid-shelf mud depocenters, we apply a weakly nonlinear model based on the variable-coefficient Gardner equation to estimate the flow fields and bottom shear stress induced by shoaling of mode-1 long internal solitary waves. Shoreward propagation of the ISWs in three representative periods (pre-, intra- and post-storm) is simulated, respectively. Transformation of the internal wave, from a single sech2 shape characterized by negative polarity and small amplitude to a dispersive trailing wave packet with varying amplitude and inverse polarity, are satisfactorily reproduced. Model results indicate enhancement of the maximum orbital velocity of the ISWs during and after the storm on the outer shelf (130–220 m WD) including the seaward margin of the mud depocenter. Bottom shear stress consequently becomes strong enough (≥0.1 Pa) to winnow unconsolidated sediment and constrains the offshore extension of the depocenter. The enhanced bottom orbital velocity and the asymmetry in the excursion direction of mode-1 long ISWs in the post-storm period prove to be efficient in transporting fine-grained sediment across shelf. Our results suggest that mid-shelf mud depocenters are not necessarily areas under permanently calm conditions where fine-grained sediment can settle straightforwardly. They could also result from convergent sediment transport from both onshore and offshore directions, and sediment may go through numerous cycles of resuspension-transport-deposition before its ultimate lasting burial. %0 journal article %@ 0452-7739 %A Rudolph, E., Brodhagen, T., Fery, N., Gaslikova, L., Grabemann, I., Meyer, E., Möller, T., Tinz, B., Weisse, R. %D 2019 %J Die Küste %N 87 %P 47-73 %R doi:10.18171/1.087111 %T Analyse extremer Sturmfluten an der deutschen Nordseeküste und ihrer möglichen Verstärkung %U https://doi.org/10.18171/1.087111 87 %X Kenntnisse über mögliche Auswirkungen schwerer Sturmfluten sowie mögliche Änderun-gen im Zuge eines anthropogenen Klimawandels sind für die Planung des Küstenschutzes von großer Bedeutung. In EXTREMENESS werden aus einem umfangreichen Modellda-tensatz bestehend aus Reanalysen, Hindcasts und Klimaprojektionen für die Fokusregion Emsästuar Sturmflutereignisse extrahiert, die extrem selten und höchst unwahrscheinlich aber potentiell mit extremen Konsequenzen verbunden sein könnten. Diese ausgewählten extremen Sturmfluten sowie ihr Potential für eine mögliche Verstärkung durch z. B. unter-schiedliche Wechselwirkungen zwischen Tidephase und Windentwicklung oder durch einen Meeresspiegelanstieg werden mit numerischen Modellen für die Nordsee und die Ästuare von Ems und Elbe untersucht und Sturmflutkenngrößen entlang der Ästuare und besonders für die Region Emden analysiert. %0 journal article %@ 1991-959X %A Primo, C., Kelemen, F., Feldmann, H., Akhtar, N., Ahrens, B. %D 2019 %J Geoscientific Model Development %N 12 %P 5077-5095 %R doi:10.5194/gmd-12-5077-2019 %T A regional atmosphere–ocean climate system model (CCLMv5.0clm7-NEMOv3.3-NEMOv3.6) over Europe including three marginal seas: on its stability and performance %U https://doi.org/10.5194/gmd-12-5077-2019 12 %X The frequency of extreme events has changed, having a direct impact on human lives. Regional climate models help us to predict these regional climate changes. This work presents an atmosphere–ocean coupled regional climate system model (RCSM; with the atmospheric component COSMO-CLM and the ocean component NEMO) over the European domain, including three marginal seas: the Mediterranean, North, and Baltic Sea. To test the model, we evaluate a simulation of more than 100 years (1900–2009) with a spatial grid resolution of about 25 km. The simulation was nested into a coupled global simulation with the model MPI-ESM in a low-resolution configuration, whose ocean temperature and salinity were nudged to the ocean–ice component of the MPI-ESM forced with the NOAA 20th Century Reanalysis (20CR). The evaluation shows the robustness of the RCSM and discusses the added value by the coupled marginal seas over an atmosphere-only simulation. The coupled system is stable for the complete 20th century and provides a better representation of extreme temperatures compared to the atmosphere-only model. The produced long-term dataset will help us to better understand the processes leading to meteorological and climate extremes. %0 journal article %@ 2296-7745 %A Taherzadeh, N., Bengfort, M., Wirtz, K. %D 2019 %J Frontiers in Marine Science %P 351 %R doi:10.3389/fmars.2019.00351 %T A Trait-Based Framework for Explaining Non-additive Effects of Multiple Stressors on Plankton Communities %U https://doi.org/10.3389/fmars.2019.00351 %X Phytoplankton communities are increasingly subject to multiple stressors of natural or anthropogenic origin. The cumulative effect of these stressors, however, may vary considerably from the sum of impacts from individual stressors. Nonlinear effects, such as changes in community traits can either boost up (synergistic) or weaken (antagonistic) single stressors. Despite previous empirical studies and meta analyses on the interaction types of various multiple stressors, a more fundamental understanding of cumulative effects is lacking. To fill this gap, we here propose a new theoretical framework that is centered on the concept of interaction traits and their trade-offs. The framework is applied to a novel size-based plankton model resolving multi-species phytoplankton-nutrients-detritus-zooplankton dynamics within the upper mixed layer. The model is validated using data from a series of outdoor mesocosm experiments. In the direct aftermath of single perturbations that increase net growth rate, here nutrient enrichment and grazer removal, the simulated phytoplankton community undergoes structural changes as visible in altered community traits. These temporal variations explain why the multiple stressor interaction switches from antagonistic to synergistic as compensatory trait variations reduce over time of the experiment. This finding can be generalized within our trait-based explanatory framework to mechanistically assess and predict effects of other stressor combinations and for other organism groups. %0 journal article %@ 0048-9697 %A Cormier, R., Elliott, M., Rice, J. %D 2019 %J Science of the Total Environment %P 293-305 %R doi:10.1016/j.scitotenv.2018.08.168 %T Putting on a bow-tie to sort out who does what and why in the complex arena of marine policy and management %U https://doi.org/10.1016/j.scitotenv.2018.08.168 %X This industry-standard system, described here with examples for the marine environment, will fulfil many of the demands by the users and uses of the marine system and the regulators of those users and uses. It allows for bridging several aspects: the management and environmental sciences, the management complexity and governance demands, the natural and social sciences and socio-economics and outcomes. Most importantly, the use of the Bow-tie approach bridges systems analysis and ecosystem complexity. At a time when scientific decisions in policy making and implementation are under question, we conclude that it provides a rigorous, transparent and defendable system of decision-making. %0 journal article %@ 0025-3227 %A Chen, H., Zhang, W., Xie, X., Ren, J. %D 2019 %J Marine Geology %P 48-66 %R doi:10.1016/j.margeo.2018.12.012 %T Sediment dynamics driven by contour currents and mesoscale eddies along continental slope: A case study of the northern South China Sea %U https://doi.org/10.1016/j.margeo.2018.12.012 %X Our modelling study indicates that both surface and bottom mesoscale eddies are essential to account for the spatial heterogeneity in sedimentation pattern along the northern South China Sea continental slope. According to simulation, the eddy front contains the highest flow velocity over a mesoscale eddy cycle (45 days), exceeding the threshold for resuspension of unconsolidated sediment (15 cm/s). As a consequence massive resuspension is produced at various sites, and redistributed by sub-mesoscale (horizontal scale of 1 to 10 km) circulations originated from an eddy-topography interaction. In contrast to the surrounding areas, which are subject to erosional forcing for a relatively long part (>7% of an eddy cycle), both the locally-confined drift and a further upstream large elongated-mounded drift experience little erosion (<2.5% of an eddy cycle), and serve as depositional centres for sediment from remote areas and erosion from adjacent areas. Our study demonstrates a promising new perspective for bridging the scales between short-term sediment dynamics and long-term sedimentation through a comparison of modelled scenarios between normal conditions and energetic events. %0 journal article %@ 2324-9250 %A Bothe, O. %D 2019 %J Eos : Earth & Space Science News %R doi:10.1029/2019EO131019 %T When does weather become climate? %U https://doi.org/10.1029/2019EO131019 %X Flexible definitions of the word “climate” may impede policy discussions on climate change. Closing apparent gaps between “climate” and “weather” may help reduce the ambiguity. %0 journal article %@ 1680-7316 %A Curci, G., Alyuz, U., Barò, R., Bianconi, R., Bieser, J., Christensen, J.H., Colette, A., Farrow, A., Francis, X., Jiménez-Guerrero, P., Im, U., Liu, P., Manders, A., Palacios-Peña, L., Prank, M., Pozzoli, L., Sokhi, R., Solazzo, E., Tuccella, P., Unal, A., Vivanco, M.G., Hogrefe, C., Galmarini, S. %D 2019 %J Atmospheric Chemistry and Physics %N 1 %P 181-204 %R doi:10.5194/acp-19-181-2019 %T Modelling black carbon absorption of solar radiation: combining external and internal mixing assumptions %U https://doi.org/10.5194/acp-19-181-2019 1 %X  %. The black carbon absorption enhancement (Eabs) in core-shell with respect to the externally mixed state is in the range 1.8–2.5, which is above the currently most accepted upper limit of ∼1.5. The partial internal mixing reduces Eabs to values more consistent with this limit. However, the spectral dependence of the absorption is not well reproduced, and the absorption Ångström exponent AAE440675 is overestimated by 70–120 %. Further testing against more comprehensive campaign data, including a full characterization of the aerosol profile in terms of chemical speciation, mixing state, and related optical properties, would help in putting a better constraint on these calculations. %0 journal article %@ 2590-1621 %A Mircea, M., Bessagnet, B., D'Isidoro, M., Pirovano, G., Aksoyoglu, S., Ciarelli, G., Tsyro, S., Manders, A., Bieser, J., Stern, R., Vivanco, M.G., Cuvelier, C., Aas, W., Prévôt, A.S.H., Aulinger, A., Briganti, G., Calori, G., Cappelletti, A., Colette, A., Couvidat, F., Fagerli, H., Finardi, S., Kranenburg, R., Rouïl, L., Silibello, C., Spindler, G., Poulain, L., Herrmann, H., Jimenez, J.L., Day, D.A., Tiitta, P., Carbone, S. %D 2019 %J Atmospheric Environment: X %P 100018 %R doi:10.1016/j.aeaoa.2019.100018 %T EURODELTA III exercise: An evaluation of air quality models’ capacity to reproduce the carbonaceous aerosol %U https://doi.org/10.1016/j.aeaoa.2019.100018 %X The carbonaceous aerosol accounts for an important part of total aerosol mass, affects human health and climate through its effects on physical and chemical properties of the aerosol, yet the understanding of its atmospheric sources and sinks is still incomplete. This study shows the state-of-the-art in modelling carbonaceous aerosol over Europe by comparing simulations performed with seven chemical transport models (CTMs) currently in air quality assessments in Europe: CAMx, CHIMERE, CMAQ, EMEP/MSC-W, LOTOS-EUROS, MINNI and RCGC. The simulations were carried out in the framework of the EURODELTA III modelling exercise and were evaluated against field measurements from intensive campaigns of European Monitoring and Evaluation Programme (EMEP) and the European Integrated Project on Aerosol Cloud Climate and Air Quality Interactions (EUCAARI). Model simulations were performed over the same domain, using as much as possible the same input data and covering four seasons: summer (1–30 June 2006), winter (8 January – 4 February 2007), autumn (17 September- 15 October 2008) and spring (25 February - 26 March 2009). The analyses of models’ performances in prediction of elemental carbon (EC) for the four seasons and organic aerosol components (OA) for the last two seasons show that all models generally underestimate the measured concentrations. The maximum underestimation of EC is about 60% and up to about 80% for total organic matter (TOM). The underestimation of TOM outside of highly polluted area is a consequence of an underestimation of secondary organic aerosol (SOA), in particular of its main contributor: biogenic secondary aerosol (BSOA). This result is independent on the SOA modelling approach used and season. The concentrations and daily cycles of total primary organic matter (TPOM) are generally better reproduced by the models since they used the same anthropogenic emissions. However, the combination of emissions and model formulation leads to overestimate TPOM concentrations in 2009 for most of the models. All models capture relatively well the SOA daily cycles at rural stations mainly due to the spatial resolution used in the simulations. For the investigated carbonaceous aerosol compounds, the differences between the concentrations simulated by different models are lower than the differences between the concentrations simulated with a model for different seasons. %0 journal article %@ 0452-7739 %A Schaper, J., Ulm, M., Arns, A., Jensen, J., Ratter, B., Weisse, R. %D 2019 %J Die Küste %N 87 %P 75-114 %R doi:10.18171/1.087112 %T Transdisziplinäres Risikomanagement im Umgang mit extremen Nordsee-Sturmfluten – Vom Modell zur Wissenschafts-Praxis-Kooperation %U https://doi.org/10.18171/1.087112 87 %X Die Region Emden-Krummhörn in Ostfriesland wird aufgrund ihrer besonderen Lage zur angrenzenden Nordsee von einer Vielzahl hydrologischer Risiken bedroht. Da z. B. große Teile der Region unter dem Meeresspiegel liegen, werden Deiche zum Schutz vor Sturm-fluten benötigt. Zudem muss Niederschlag aus dem tiefliegenden Hinterland mit Hilfe von Sielen und Schöpfwerken entwässert werden. Im Zuge des Klimawandels droht sich diese multiple Risikolage von mehreren Seiten zu verschärfen, da Ereignisse wie Starkregen und Sturmfluten zukünftig häufiger und/oder extremer auftreten können. Um diesen steigen-den Herausforderungen im Küsten- und Katastrophenschutz zu begegnen, wurden im For-schungsprojekt „EXTREMENESS – Extreme Nordseesturmfluten und mögliche Auswir-kungen“ Sturmflutrisiken für die Region Emden-Krummhörn transdisziplinär untersucht. Im vorliegenden Beitrag werden (a) das transdisziplinäre Risikomanagement im Umgang mit extremen, möglichen Nordseesturmfluten in einem Wissenschafts-Praxis-Kooperati-onsforum beschrieben und (b) die auf hydrodynamisch-numerischen Simulationen basie-renden Schadenspotenzialanalysen vorgestellt, die für die Bewertung und Diskussion der Konsequenzen im Rahmen des Kooperationsforums verwendet wurden. Wissenschaftler und Fachleute aus der Praxis haben dabei zunächst die Risikovorstellungen und -wahrneh-mungen sowie unwahrscheinliche Extremereignisse identifiziert (Was ist denkbar?), anschlie-ßend mögliche Auswirkungen von Katastrophenereignissen auf neuralgische Punkte an-hand von Versagensketten entwickelt und numerisch modelliert (Was passiert, wenn?) sowie abschließend Handlungsoptionen und Maßnahmen abgeleitet und bewertet (Was tun?). %0 journal article %@ 2073-4441 %A Storto, A., Bonaduce, A., Feng, X., Yang, C. %D 2019 %J Water %N 10 %P 1987 %R doi:10.3390/w11101987 %T Steric Sea Level Changes from Ocean Reanalyses at Global and Regional Scales %U https://doi.org/10.3390/w11101987 10 %X Sea level has risen significantly in the recent decades and is expected to rise further based on recent climate projections. Ocean reanalyses that synthetize information from observing networks, dynamical ocean general circulation models, and atmospheric forcing data offer an attractive way to evaluate sea level trend and variability and partition the causes of such sea level changes at both global and regional scales. Here, we review recent utilization of reanalyses for steric sea level trend investigations. State-of-the-science ocean reanalysis products are then used to further infer steric sea level changes. In particular, we used an ensemble of centennial reanalyses at moderate spatial resolution (between 0.5 × 0.5 and 1 × 1 degree) and an ensemble of eddy-permitting reanalyses to quantify the trends and their uncertainty over the last century and the last two decades, respectively. All the datasets showed good performance in reproducing sea level changes. Centennial reanalyses reveal a 1900–2010 trend of steric sea level equal to 0.47 ± 0.04 mm year−1, in agreement with previous studies, with unprecedented rise since the mid-1990s. During the altimetry era, the latest vintage of reanalyses is shown to outperform the previous ones in terms of skill scores against the independent satellite data. They consistently reproduce global and regional upper ocean steric expansion and the association with climate variability, such as ENSO. However, the mass contribution to the global mean sea level rise is varying with products and its representability needs to be improved, as well as the contribution of deep and abyssal waters to the steric sea level rise. Similarly, high-resolution regional reanalyses for the European seas provide valuable information on sea level trends, their patterns, and their causes. %0 journal article %@ 0452-7739 %A Holzwarth, I., Weilbeer, H., Wirtz, K. %D 2019 %J Die Küste %N 87 %P 261-282 %R doi:10.18171/1.087109 %T The effect of bathymetric modification on water age in the Elbe Estuary %U https://doi.org/10.18171/1.087109 87 %X dynamics in the estuary. %0 journal article %@ 0452-7739 %A Weisse, R., Grabemann, I., Gaslikova, L., Meyer, E., Tinz, B., Fery, N., Möller, T., Rudolph, E., Brodhagen, T., Arns, A., Jensen, J., Ulm, M., Ratter, B., Schaper, J. %D 2019 %J Die Küste %N 87 %P 39-45 %R doi:10.18171/1.087110 %T Extreme Nordseesturmfluten und mögliche Auswirkungen: Das EXTREMENESS Projekt %U https://doi.org/10.18171/1.087110 87 %X Das Projekt EXTREMENESS verfolgte das Ziel, extreme Nordseesturmfluten zu identi-fizieren und zu beschreiben, die zum einen extrem unwahrscheinlich, zum anderen aber noch physikalisch plausibel sind. Darauf aufbauend wurden in einem transdisziplinären Ansatz mögliche Auswirkungen untersucht und diskutiert, welche Maßnahmen und Hand-lungsoptionen im Umgang mit solchen Extremereignissen existieren. EXTREMENESS leistet damit wichtige Beiträge zur Diskussion über Anpassung, Formen und Notwendig-keiten eines zukünftigen Küstenschutzes und Risikomanagements %0 journal article %@ 1755-876X %A von Schuckmann, K., Le Traon, P.-Y., Smith, N., Staneva, J. %D 2019 %J Journal of Operational Oceanography %N sup1 %P S1-S123 %R doi:10.1080/1755876X.2019.1633075 %T Copernicus Marine Service Ocean State Report, Issue 3 %U https://doi.org/10.1080/1755876X.2019.1633075 sup1 %X The fundamental role of the ocean for life and well-being on Earth is more and more recognised at the highest political level. In 2015, the United Nations (UN) Sustainable Development Goals (SDGs) of the 2030 Agenda for Sustainable Development were adopted by world leaders. The SDG 14 ‘Conserve and sustainably use the oceans, seas and marine resources for sustainable development’ is dedicated to the oceans. The mention of the ocean in the Paris Agreement signed in 2016 marked a decisive milestone. In 2018, the UN Decade of Ocean Science for Sustainable Development (2021–2030) has been proclaimed (https://en.unesco.org/ocean-decade): The Intergovernmental Oceanographic Commission of UNESCO will gather ocean stakeholders worldwide behind a common framework to foster evidence-based policy-making. In fall 2019, the IPCC special report on ocean and cryosphere will be published, and will provide an opportunity to increase awareness and action before COP251 (already claimed as ‘Blue COP’). %0 journal article %@ 0025-3227 %A Zhang, W., Didenkulova, I., Kurkina, O., Cui, Y., Haberkern, J., Aepfler, R., Santos, A., Zhang, H., Hanebuth, T. %D 2019 %J Marine Geology %P 21 %R doi:10.1016/j.margeo.2019.01.012 %T Corrigendum to “Internal solitary waves control offshore extension of mud depocenters on the NW Iberian shelf” [Mar. Geol. 409 (2019) 15–30] %U https://doi.org/10.1016/j.margeo.2019.01.012 %X %0 journal article %@ 0016-7185 %A de Guttry, C., Süsser, D., Döring, M. %D 2019 %J Geoforum %P 92-100 %R doi:10.1016/j.geoforum.2019.06.015 %T Situating climate change: Psychological distances as tool to understand the multifaceted dimensions of climate change meanings %U https://doi.org/10.1016/j.geoforum.2019.06.015 %X In recent years, considerable efforts have been devoted to exploring and understanding how people attribute meaning to and engage with climate change. Although the relevance of society in regional mitigation and adaptation to climate change is now recognised, it is still not clear how local places and social climate change meanings inform each other. Taking this gap in research as a starting point, we investigate people’s ‘emplaced’ climate meanings with the approach of psychological distances (geographical, temporal and social). Using a grounded method and 36 semi-structured interviews with inhabitants of North Frisia (Germany) – a region that has always been profoundly affected by environmental change – we disentangle the different distances and proximities that permeate and create local climate change meanings. Overall, we demonstrate (1) the dynamic nature of psychological distances and proximities producing climate change meanings and we reveal (2) the importance of a place-based approach for analysing the abstract entity of climate change. %0 journal article %@ 0964-5691 %A Hassler, B., Blazauskas, N., Gee, K., Luttmann, A., Morf, A., Piwowarczyk, J., Saunders, F., Stalmokaite, I., Strand, H., Zaucha, J. %D 2019 %J Ocean & Coastal Management %P 254-263 %R doi:10.1016/j.ocecoaman.2018.12.025 %T New generation EU directives, sustainability, and the role of transnational coordination in Baltic Sea maritime spatial planning %U https://doi.org/10.1016/j.ocecoaman.2018.12.025 %X The EU MSP Directive is an example of a so-called new generation directive, which gives Member States room for adaptation to national contexts. The main objective in this article is to identify and analyse potential obstacles to effective and efficient planning caused by the diversity among national MSP frameworks that the Directive's broad regulatory boundaries have led to. It is shown that planning approaches can differ substantially between neighbouring countries, which can make it challenging to coordinate across national borders. Divergence between national MSP frameworks can also emerge from how political, jurisdictional and, administrative systems and traditions are organised in different Member States. It is shown that neighbouring countries can diverge substantially in how the ecological, economic and social dimensions of sustainability are balanced, which can make transnational coordination challenging. Furthermore, it is shown that stakeholder consultations differ among Member States in terms of, for example, who were invited, how the consultations were undertaken, and the role they play in relation to political decision-making. Because of these, and other differences in how MSP frameworks are being developed in the Member States, it is suggested that regional integration should be promoted with discretion. From this perspective, it seems reasonable to embrace diversity, while simultaneously promoting the adaptive management of coordination problems at lower levels, when, or if, they emerge or can be foreseen. Thus, increased integration of national MSP frameworks should be viewed as an instrument to reduce concrete efficiency losses, rather than as an intrinsic good. %0 journal article %@ 0964-5691 %A Piwowarczyk, J., Gee, K., Gilek, M., Hassler, B., Luttmann, A., Maack, L., Matczak, M., Morf, A., Saunders, F., Stalmokaite, I., Zaucha, J. %D 2019 %J Ocean & Coastal Management %P 98-109 %R doi:10.1016/j.ocecoaman.2019.03.023 %T Insights into integration challenges in the Baltic Sea Region marine spatial planning: Implications for the HELCOM-VASAB principles %U https://doi.org/10.1016/j.ocecoaman.2019.03.023 %X %0 journal article %@ 0964-5691 %A Morf, A., Moodie, J., Gee, K., Giacometti, A., Kull, M., Piwowarczyk, J., Schiele, K., Zaucha, J., Kellecioglu, I., Luttmann, A., Strand, H. %D 2019 %J Ocean and Coastal Management %P 200-212 %R doi:10.1016/j.ocecoaman.2019.04.009 %T Towards sustainability of marine governance: Challenges and enablers for stakeholder integration in transboundary marine spatial planning in the Baltic Sea %U https://doi.org/10.1016/j.ocecoaman.2019.04.009 %X Integrating stakeholder knowledge, views and needs in marine or maritime spatial planning (MSP) processes is important from a governance and social sustainability perspective both for MSP practitioners and for the evolving field of MSP research. Transboundary MSP appears particularly challenging for participation, which is why it is important to identify opportunities and address obstacles for stakeholder integration in this specific context. This article examines how stakeholder integration is currently practiced in the Baltic Sea Region (BSR), an enclosed sea where policy coherence and addressing conflicting interests across borders are especially relevant. It synthesises a range of challenges and enablers for stakeholder participation and mobilisation that have emerged from two transboundary MSP research and development projects, BaltSpace and Baltic SCOPE. The article finds that with the exception of statutory authorities, stakeholder engagement in the BSR is mostly limited to self-motivated stakeholders and consultation rather than more inclusive forms of participation. This can reduce the quality and legitimacy of MSP processes and risks to concentrate power in the hands of a small group of actors. For transboundary stakeholder integration to become more interactive and effective, five types of challenges need attention, regarding a) timing, b) governance systems, c) capacity and processes, d) stakeholder characteristics and e) knowledge and language. These obstacles can be addressed by (1) a dedicated research and development agenda that critically reflects on integrative tools and processes, and (2) by encouraging transnational institutions in the BSR to devote more resources to transboundary stakeholder integration and adopt flexible and adaptive strategies and tools that can facilitate stakeholder involvement throughout the MSP policy cycle. %0 journal article %@ 0930-7575 %A Akhtar, N., Krug, A., Brauch, J., Arsouze, T., Dieterich, C., Ahrens, B. %D 2019 %J Climate Dynamics %P 5967-5984 %R doi:10.1007/s00382-019-04906-x %T European marginal seas in a regional atmosphere–ocean coupled model and their impact on Vb-cyclones and associated precipitation %U https://doi.org/10.1007/s00382-019-04906-x %X Vb-cyclones are extratropical cyclones propagating from the Western Mediterranean Sea and traveling across the Eastern Alps into the Baltic region. With these cyclones, extreme precipitation over Central Europe potentially triggers significant flood events. Understanding the prediction ability of Vb-cyclones would lower risks from adverse impacts. This study analyzes the robustness of an atmosphere–ocean regional coupled model, including interactive models for the Mediterranean Sea (MED) and North and Baltic Seas (NORDIC) in reproducing observed Vb-cyclone characteristics. We use the regional climate model (RCM) COSMO-CLM (CCLM) in stand-alone and coupled with the ocean model NEMO configurations for the EURO-CORDEX domain from 1979 to 2014, driven by the ERA-Interim reanalysis. Sea surface temperature (SST) is evaluated to demonstrate the stability and reliability of the coupled configurations. Compared to observations, simulated SSTs show biases (~ 1 °C), especially during winter and summer. Generally, all model configurations are able to replicate Vb-cyclones, their trajectories, and associated precipitation fields. Cyclone trajectories are comparably well simulated with the coupled models, as with the stand-alone simulation which is driven by the reanalysis SST in the MED and NORDIC seas. The cyclone intensity shows large deviations from reanalysis reference in the simulations with the interactive MED Sea, and smallest with CCLM. Precipitation characteristics are similarly simulated in the coupled and stand-alone (with reanalysis SST) simulations. The results suggest that our coupled RCM is useful for studying the impacts of highly resolved and interactively simulated SSTs on European extreme events and regional climate, a crucial prerequisite for understanding future climate conditions. %0 journal article %@ 0034-0111 %A Walsh, C., Kannen, A. %D 2019 %J Raumforschung und Raumordnung %N 2 %P 147-164 %R doi:10.2478/rara-2019-0020 %T Planning at Sea: Shifting planning practices at the German North Sea coast %U https://doi.org/10.2478/rara-2019-0020 2 %X Coastal and marine areas represent an increasingly important and relevant action space for spatial planning. However, to a large extent marine (or maritime) spatial planning has emerged separately from terrestrial spatial planning, constituting its own epistemic community. In particular, previous studies indicate that Marine Spatial Planning often follows an expert-driven resource management rationale focused on sea-use regulation. This paper examines practices of Marine Spatial Planning and Integrated Coastal Zone Management at the German North Sea coast. The paper focuses in particular on the engagement of spatial planners with these practices and their perception of their role therein. We seek to understand what form spatial planning at the coast and at sea currently takes and how this might develop in the future in response to current and anticipated policy developments. We argue for the necessity of a communicative, cross-sectoral approach to spatial planning at sea, providing a spatial vision for the future that extends from the Exclusive Economic Zone to encompass both the coastal waters of the federal states and the land-sea interface in a substantive manner. %0 journal article %@ 2296-7745 %A Ponte, R.M., Carson, M., Cirano, M., Domingues, C.M., Jevrejeva, S., Marcos, M., Mitchum, G., van de Wal, R.S.W., Woodworth, P.L., Ablain, M., Ardhuin, F., Ballu, V., Becker, M., Benveniste, J., Birol, F., Bradshaw, E., Cazenave, A., De Mey-Frémaux, P., Durand, F., Ezer, T., Fu, L.-L., Fukumori, I., Gordon, K., Gravelle, M., Griffies, S.M., Han, W., Hibbert, A., Hughes, C.W., Idier, D., Kourafalou, V.H., Little, C.M., Matthews, A., Melet, A., Merrifield, M., Meyssignac, B., Minobe, S., Penduff, T., Picot, N., Piecuch, C., Ray, R.D., Rickards, L., Santamaría-Gómez, A., Stammer, D., Staneva, J., Testut, L., Thompson, K., Thompson, P., Vignudelli, S., Williams, J., Williams, S.D.P., Wöppelmann, G., Zanna, L., Zhang, X. %D 2019 %J Frontiers in Marine Science %P 437 %R doi:10.3389/fmars.2019.00437 %T Towards Comprehensive Observing and Modeling Systems for Monitoring and Predicting Regional to Coastal Sea Level %U https://doi.org/10.3389/fmars.2019.00437 %X A major challenge for managing impacts and implementing effective mitigation measures and adaptation strategies for coastal zones affected by future sea level (SL) rise is our limited capacity to predict SL change at the coast on relevant spatial and temporal scales. Predicting coastal SL requires the ability to monitor and simulate a multitude of physical processes affecting SL, from local effects of wind waves and river runoff to remote influences of the large-scale ocean circulation on the coast. Here we assess our current understanding of the causes of coastal SL variability on monthly to multi-decadal timescales, including geodetic, oceanographic and atmospheric aspects of the problem, and review available observing systems informing on coastal SL. We also review the ability of existing models and data assimilation systems to estimate coastal SL variations and of atmosphere-ocean global coupled models and related regional downscaling efforts to project future SL changes. We discuss (1) observational gaps and uncertainties, and priorities for the development of an optimal and integrated coastal SL observing system, (2) strategies for advancing model capabilities in forecasting short-term processes and projecting long-term changes affecting coastal SL, and (3) possible future developments of sea level services enabling better connection of scientists and user communities and facilitating assessment and decision making for adaptation to future coastal SL change. %0 journal article %@ 1812-0784 %A Lewis, H., Castillo Sanchez, J., Siddorn, J., King, R., Tonani, M., Saulter, A., Sykes, P., Pequignet, A., Weedon, G., Palmer, T., Staneva, J., Bricheno, L. %D 2019 %J Ocean Science %N 3 %P 669-690 %R doi:10.5194/os-15-669-2019 %T Can wave coupling improve operational regional ocean forecasts for the north-west European Shelf? %U https://doi.org/10.5194/os-15-669-2019 3 %X Summary forecast metrics demonstrate that the ocean–wave coupled system is a viable evolution for future operational implementation. When results are considered in more depth, wave coupling was found to result in an annual cycle of relatively warmer winter and cooler summer sea surface temperatures for seasonally stratified regions of the NWS. This is driven by enhanced mixing due to waves, and a deepening of the ocean mixed layer during summer. The impact of wave coupling is shown to be reduced within the mixed layer with assimilation of ocean observations. Evaluation of salinity and ocean currents against profile measurements in the German Bight demonstrates improved simulation with wave coupling relative to control simulations. Further, evidence is provided of improvement to simulation of extremes of sea surface height anomalies relative to coastal tide gauges. %0 journal article %@ 2296-7745 %A Palazov, A., Ciliberti, S., Peneva, E., Gregoire, M., Staneva, J., Lemieux-Dudon, B., Masina, S., Pinardi, N., Vandenbulcke, L., Behrens, A., Lima, L., Coppini, G., Marinova, V., Slabakova, V., Lecci,R., Creti, S., Palermo, F., Stefanizzi, L., Valcheva, N., Agostini, P. %D 2019 %J Frontiers in Marine Science %P 315 %R doi:10.3389/fmars.2019.00315 %T Black Sea Observing System %U https://doi.org/10.3389/fmars.2019.00315 %X The ultimate goal of modern operational oceanography are end user oriented products with high scientific quality. Beneficiaries are the governmental services, coast and offshore based enterprises and research institutions that make use of the products generated by operational oceanography. Direct users are coastal managers, shipping, search and rescue, oil spill combat, offshore industry, ports, fishing, tourism, and recreation industry. Indirect beneficiaries, through climate forecasting based on ocean observations, are food, energy, water and medical suppliers. Availability of updated information on the actual state as well as forecast of marine environment is essential for the success and safety of maritime operations in the offshore industry. Various systems for the collection and presentation of marine data for the needs of different users have been developed and put in operation in the Black Sea. The systems are located both along the coast and in the open sea and the information they provide is used by both the maritime industry and the widest range of users. The Black Sea Monitoring and Forecasting Center in the frame of the Copernicus Marine Service is providing regular and systematic information about the physical state of the ocean, marine ecosystem and wave conditions in the Black Sea area, assimilating observations, keeping efficient operations, advanced technology and high quality modeling products. Combining and optimizing in situ, remote sensing, modeling and forecasting into a Black Sea observing system is a task that has to be solved, and that will allow to get a more complete and comprehensive picture of the state of the marine environment as well as to forecast future changes of physical and biogeochemical state of the Black Sea and the Black Sea ecosystem. %0 journal article %@ 1726-4170 %A Charrieau, L., Ljung, K., Schenk, F., Daewel, U., Kritzberg, E., Filipsson, H. %D 2019 %J Biogeosciences %N 19 %P 3835-3852 %R doi:10.5194/bg-16-3835-2019 %T Rapid environmental responses to climate-induced hydrographic changes in the Baltic Sea entrance %U https://doi.org/10.5194/bg-16-3835-2019 19 %X The Öresund (the Sound), which is a part of the Danish straits, is linking the marine North Sea and the brackish Baltic Sea. It is a transition zone where ecosystems are subjected to large gradients in terms of salinity, temperature, carbonate chemistry, and dissolved oxygen concentration. In addition to the highly variable environmental conditions, the area is responding to anthropogenic disturbances in, e.g., nutrient loading, temperature, and pH. We have reconstructed environmental changes in the Öresund during the last ca. 200 years, and especially dissolved oxygen concentration, salinity, organic matter content, and pollution levels, using benthic foraminifera and sediment geochemistry. Five zones with characteristic foraminiferal assemblages were identified, each reflecting the environmental conditions for the respective period. The largest changes occurred around 1950, when the foraminiferal assemblage shifted from a low diversity fauna dominated by the species Stainforthia fusiformis to higher diversity and abundance and dominance of the Elphidium species. Concurrently, the grain-size distribution shifted from clayey to sandier sediment. To explore the causes of the environmental changes, we used time series of reconstructed wind conditions coupled with large-scale climate variations as recorded by the North Atlantic Oscillation (NAO) index as well as the ECOSMO II model of currents in the Öresund area. The results indicate increased changes in the water circulation towards stronger currents in the area after the 1950s. The foraminiferal fauna responded quickly (<10 years) to the environmental changes. Notably, when the wind conditions, and thereby the current system, returned in the 1980s to the previous pattern, the foraminiferal assemblage did not rebound. Instead, the foraminiferal faunas displayed a new equilibrium state. %0 journal article %@ 2077-1312 %A Bonaduce, A., Staneva, J., Behrens, A., Bidlot, J., Wilcke, R. %D 2019 %J Journal of Marine Science and Engineering %N 6 %P 166 %R doi:10.3390/jmse7060166 %T Wave Climate Change in the North Sea and Baltic Sea %U https://doi.org/10.3390/jmse7060166 6 %X Wave climate change by the end of the 21st century (2075–2100) was investigated using a regional wave climate projection under the RCP 8.5 scenario. The performance of the historical run (1980–2005) in representing the present wave climate was assessed when compared with in situ (e.g., GTS) and remote sensing (i.e., Jason-1) observations and wave hindcasts (e.g., ERA5-hindcast). Compared with significant wave height observations in different subdomains, errors on the order of 20–30% were observed. A Principal Component (PC) analysis showed that the temporal leading modes obtained from in situ data were well correlated (0.9) with those from the historical run. Despite systematic differences (10%), the general features of the present wave climate were captured by the historical run. In the future climate projection, with respect to the historical run, similar wave climate change patterns were observed when considering both the mean and severe wave conditions, which were generally larger during summer. The range of variation in the projected extremes (±10%) was consistent with those observed in previous studies both at the global and regional spatial scales. The most interesting feature was the projected increase in extreme wind speed, surface Stokes drift speed and significant wave height in the Northeast Atlantic. On the other hand, a decrease was observed in the North Sea and the southern part of the Baltic Sea basin, while increased extreme values occurred in the Gulf of Bothnia during winter. %0 journal article %@ 2296-7745 %A Davidson, F., Alvera-Azcárate, A., Barth, A., Brassington, G.B., Chassignet, E.P., Clementi, E., De Mey-Frémaux, P., Divakaran, P., Harris, C., Hernandez, F., Hogan, P., Hole, L.R., Holt, J., Liu, G., Lu, Y., Lorente, P., Maksymczuk, J., Martin, M., Mehra, A., Melsom, A., Mo, H., Moore, A., Oddo, P., Pascual, A., Pequignet, A.-C., Kourafalou, V., Ryan, A., Siddorn, J., Smith, G., Spindler, D., Spindler, T., Stanev, E.V., Staneva, J., Storto, A., Tanajura, C., Vinayachandran, P.N., Wan, L., Wang, H., Zhang, Y., Zhu, X., Zu, Z. %D 2019 %J Frontiers in Marine Science %P 450 %R doi:10.3389/fmars.2019.00450 %T Synergies in Operational Oceanography: The Intrinsic Need for Sustained Ocean Observations %U https://doi.org/10.3389/fmars.2019.00450 %X Operational oceanography can be described as the provision of routine oceanographic information needed for decision-making purposes. It is dependent upon sustained research and development through the end-to-end framework of an operational service, from observation collection to delivery mechanisms. The core components of operational oceanographic systems are a multi-platform observation network, a data management system, a data assimilative prediction system, and a dissemination/accessibility system. These are interdependent, necessitating communication and exchange between them, and together provide the mechanism through which a clear picture of ocean conditions, in the past, present, and future, can be seen. Ocean observations play a critical role in all aspects of operational oceanography, not only for assimilation but as part of the research cycle, and for verification and validation of products. Data assimilative prediction systems are advancing at a fast pace, in tandem with improved science and the growth in computing power. To make best use of the system capability these advances would be matched by equivalent advances in operational observation coverage. This synergy between the prediction and observation systems underpins the quality of products available to stakeholders, and justifies the need for sustained ocean observations. In this white paper, the components of an operational oceanographic system are described, highlighting the critical role of ocean observations, and how the operational systems will evolve over the next decade to improve the characterization of ocean conditions, including at finer spatial and temporal scales. %0 journal article %@ 2296-7745 %A Fujii, Y., Remy, E., Zuo, H., Oke, P.R., Halliwell, G.R., Gasparin, F., Benkiran, M., Loose, N., Cummings, J., Xie, J., Xue, Y., Masuda, S., Smith, G.C., Balmaseda, M.A., Germineaud, C., Lea, D.J., Larnicol, G., Bertino, L., Bonaduce, A., Brasseur, P., Donlon, C., Heimbach, P., Kim, Y., Kourafalou, V., Le Traon, P.Y., Martin, M.J., Paturi, S., Tranchant, B., Usui, N. %D 2019 %J Frontiers in Marine Science %P 417 %R doi:10.3389/fmars.2019.00417 %T Observing System Evaluation Based on Ocean Data Assimilation and Prediction Systems: On-Going Challenges and a Future Vision for Designing and Supporting Ocean Observational Networks %U https://doi.org/10.3389/fmars.2019.00417 %X This paper summarizes recent efforts on Observing System Evaluation (OS-Eval) by the Ocean Data Assimilation and Prediction (ODAP) communities such as GODAE OceanView and CLIVAR-GSOP. It provides some examples of existing OS-Eval methodologies, and attempts to discuss the potential and limitation of the existing approaches. Observing System Experiment (OSE) studies illustrate the impacts of the severe decrease in the number of TAO buoys during 2012–2014 and TRITON buoys since 2013 on ODAP system performance. Multi-system evaluation of the impacts of assimilating satellite sea surface salinity data based on OSEs has been performed to demonstrate the need to continue and enhance satellite salinity missions. Impacts of underwater gliders have been assessed using Observing System Simulation Experiments (OSSEs) to provide guidance on the effective coordination of the western North Atlantic observing system elements. OSSEs are also being performed under H2020 AtlantOS project with the goal to enhance and optimize the Atlantic in-situ networks. Potential of future satellite missions of wide-swath altimetry and surface ocean currents monitoring is explored through OSSEs and evaluation of Degrees of Freedom for Signal (DFS). Forecast Sensitivity Observation Impacts (FSOI) are routinely evaluated for monitoring the ocean observation impacts in the US Navy's ODAP system. Perspectives on the extension of OS-Eval to coastal regions, the deep ocean, polar regions, coupled data assimilation, and biogeochemical applications are also presented. Based on the examples above, we identify the limitations of OS-Eval, indicating that the most significant limitation is reduction of robustness and reliability of the results due to their system-dependency. The difficulty of performing evaluation in near real time is also critical. A strategy to mitigate the limitation and to strengthen the impact of evaluations is discussed. In particular, we emphasize the importance of collaboration within the ODAP community for multi-system evaluation and of communication with ocean observational communities on the design of OS-Eval, required resources, and effective distribution of the results. Finally, we recommend further developing OS-Eval activities at international level with the support of the international ODAP (e.g., OceanPredict and CLIVAR-GSOP) and observational communities. %0 journal article %@ 0941-2948 %A Djath, B., Schulz-Stellenfleth, J. %D 2019 %J Meteorologische Zeitschrift %N 6 %P 499-515 %R doi:10.1127/metz/2019/0992 %T Wind speed deficits downstream offshore wind parks – A new automised estimation technique based on satellite synthetic aperture radar data %U https://doi.org/10.1127/metz/2019/0992 6 %X Wind speed deficits behind offshore wind parks in the German Bight are estimated from satellite synthetic aperture radar (SAR) data using a new filter technique. The deficit computation requires knowledge about the undisturbed wind field, which is derived by a two-dimensional (2D) convolution filter tailored to the geometry of the wake. Both the wind direction and the size of the wind farm are taken into account. The most relevant scale for the wind speed deficit estimator (WISDEM) is the width ξ$\xi$ of the wake. Unlike approaches used so far, the proposed technique is suitable for a full automisation of the estimation process. Furthermore, the rigorous definition of the method and the reproducibility of the results can help in the consistent analysis of big data sets and the meaningful intercomparison of different geographic study areas. The filter is applied to Sentinel‑1 SAR data demonstrating the ability of the method to quantify and visualise wind speed deficits in a very efficient way. The method also allows the study of the 2D structure of wakes, in particular curved shapes, which are found frequently. A statistical wake analysis is performed for one year of data showing the most frequent occurrence of wakes during the spring and summer seasons. According to mast measurements taken at the FINO‑1 platform, this period is characterised by relatively strong atmospheric stability. Error estimates are derived for WISDEM wind speed deficit estimates based on a 2D spectral analysis of a Sentinel‑1 SAR data set acquired over one year. The impact of the wake filter on the background wind spectrum is quantified by application of the convolution theorem. The deficit estimation error is shown to increase with decreasing deficit values and with increasing wake width. The error is most sensitive to spectral components with wavelength in the across wake direction near 2ξ$2\xi$. The slope of the derived wind spectra is very close to the Kolmogorov k-5∕3$k^{-5/3}$ law, at least down to wave length of about 3 km. A significant dependence of the spectra on the atmospheric stability was found with energy levels increasing with instability. This relationship is beneficial for wake estimations, because wakes are more likely to occur in stable conditions, where relatively homogeneous background wind fields lead to reduced deficit estimation errors. %0 journal article %@ 2296-7745 %A Le Traon, P.Y., Reppucci, A., Fanjul, E.A., Aouf, L., Behrens, A., Belmonte, M., Bentamy, A., Bertino, L., Brando, V.E., Kreiner, M.B., Benkiran, M., Carval, T., Ciliberti, S.A., Claustre, H., Clementi, E., Coppini, G., Cossarini, G., De Alfonso Alonso-Muñoyerro, M., Delamarche, A., Dibarboure, G., Dinessen, F., Drevillon, M., Drillet, Y., Faugere, Y., Fernández, V., Fleming, A., Garcia-Hermosa, M.I., Sotillo, M.G., Garric, G., Gasparin, F., Giordan, C., Gehlen, M., Gregoire, M.L., Guinehut, S., Hamon, M., Harris, C., Hernandez, F., Hinkler, J.B., Hoyer, J., Karvonen, J., Kay, S., King, R., Lavergne, T., Lemieux-Dudon, B., Lima, L., Mao, C., Martin, M.J., Masina, S., Melet, A., Nardelli, B.B., Nolan, G., Pascual, A., Pistoia, J., Palazov, A., Piolle, J.F., Pujol, M.I., Pequignet, A.C., Peneva, E., Gómez, B.P., de la Villeon, L.P., Pinardi, N., Pisano, A., Pouliquen, S., Reid, R., Remy, E., Santoleri, R., Siddorn, J., She, J., Staneva, J., Stoffelen, A., Tonani, M., Vandenbulcke, L., von Schuckmann, K., Volpe, G., Wettre, C., Zacharioudaki, A. %D 2019 %J Frontiers in Marine Science %P 234 %R doi:10.3389/fmars.2019.00234 %T From Observation to Information and Users: The Copernicus Marine Service Perspective %U https://doi.org/10.3389/fmars.2019.00234 %X The Copernicus Marine Environment Monitoring Service (CMEMS) provides regular and systematic reference information on the physical and biogeochemical ocean and sea-ice state for the global ocean and the European regional seas. CMEMS serves a wide range of users (more than 15,000 users are now registered to the service) and applications. Observations are a fundamental pillar of the CMEMS value-added chain that goes from observation to information and users. Observations are used by CMEMS Thematic Assembly Centres (TACs) to derive high-level data products and by CMEMS Monitoring and Forecasting Centres (MFCs) to validate and constrain their global and regional ocean analysis and forecasting systems. This paper presents an overview of CMEMS, its evolution, and how the value of in situ and satellite observations is increased through the generation of high-level products ready to be used by downstream applications and services. The complementary nature of satellite and in situ observations is highlighted. Long-term perspectives for the development of CMEMS are described and implications for the evolution of the in situ and satellite observing systems are outlined. Results from Observing System Evaluations (OSEs) and Observing System Simulation Experiments (OSSEs) illustrate the high dependencies of CMEMS systems on observations. Finally future CMEMS requirements for both satellite and in situ observations are detailed. %0 journal article %@ 2073-4441 %A Campos, Á., García-Valdecasas, J., Molina, R., Castillo, C., Álvarez-Fanjul, E., Staneva, J. %D 2019 %J Water %N 10 %P 2153 %R doi:10.3390/w11102153 %T Addressing Long-Term Operational Risk Management in Port Docks under Climate Change Scenarios—A Spanish Case Study %U https://doi.org/10.3390/w11102153 10 %X Ports are strategic hubs of the logistic chain and are likely to be exposed to natural hazard events. Variation of metocean agents derived from climate change, such as sea level rise or changes in the magnitude, frequency, duration, and direction of storms, can modify the infrastructural and operational vulnerability of port areas and activities, demanding the development of adaptation or mitigation strategies. In this context, the present paper is aimed to propose a downscaling methodology for addressing local effects at port scale. In addition, based on previously identifying and defining the Areas of Operational Interest (AOIs) inside ports, an approach towards the evaluation of operational vulnerability is offered. The whole process is applied, as a practical case, to the Port of Gijón (Spain) for different General Circulation Models (GCMs), concentration scenarios, and time horizons. The results highlight, in line with other publications, that inter-model differences are, so far, more significant than intra-model differences from dissimilar time horizons or concentration scenarios. %0 journal article %@ 0278-4343 %A Stanev, E., Badewien, T., Freund, H., Grayek, S., Hahner, F., Meyerjürgens, J., Ricker, M., Schöneich-Argent, R., Wolff, J., Zielinski, O. %D 2019 %J Continental Shelf Research %P 24-32 %R doi:10.1016/j.csr.2019.03.003 %T Extreme westward surface drift in the North Sea: Public reports of stranded drifters and Lagrangian tracking %U https://doi.org/10.1016/j.csr.2019.03.003 %X Observations using two kinds of drifters were carried out in the southern North Sea aiming to study the propagation pathways of marine litter. One drifter, which was driven by the upper layer currents, was equipped with Global Positioning System. Further 1600 wooden drifters, mostly driven by wind and Stokes drift, were released offshore in German waters. The detailed reports of stranded wooden drifters from members of the public, the majority of which are likely to be non-scientists, provided a valuable contribution to the drifter experiment demonstrating the usefulness of citizen science. In 2018, an extreme wind event reversed the circulation of North Sea for more than a month which resulted in a large number of wooden drifters being washed ashore on the British coast. Lagrangian numerical experiments, calibrated using data from the drifter observations, helped explain the anomalous transport and the reversal of the circulation at the sea surface and in deeper layers. The plausibility of similar events during past decades has also been estimated using data from atmospheric analyses. Events as strong as the one observed in 2018 occurred only four times in the last 40 years. %0 journal article %@ 1755-876X %A Álvarez Fanjul, E., Pascual Collar, Á., Pérez Gómez, B., De Alfonso, M., García Sotillo, M., Staneva, J., Clementi, E., Grandi, A., Zacharioudaki, A., Korres, G., Ravdas, M., Renshaw, R., Tinker, J., Raudsepp, U., Lagemaa, P., Maljutenko, I., Geyer, G., Müller, M., Yumruktepe, V. %D 2019 %J Journal of Operational Oceanography %N sup1 %P s31-s42 %R doi:10.1080/1755876X.2019.1633075 %T Sea level, sea surface temperature and SWH extreme percentiles: combined analysis from model results and in situ observations %U https://doi.org/10.1080/1755876X.2019.1633075 sup1 %X %0 journal article %@ 1942-2466 %A Mauritsen, T., Bader, J., Becker, T., Hagemann, S., Tian, F. %D 2019 %J Journal of Advances in Modeling Earth Systems : JAMES %N 4 %P 998-1038 %R doi:10.1029/2018MS001400 %T Developments in the MPI‐M Earth System Model version 1.2 (MPI‐ESM1.2) and Its Response to Increasing CO2 %U https://doi.org/10.1029/2018MS001400 4 %X A new release of the Max Planck Institute for Meteorology Earth System Model version 1.2 (MPI‐ESM1.2) is presented. The development focused on correcting errors in and improving the physical processes representation, as well as improving the computational performance, versatility, and overall user friendliness. In addition to new radiation and aerosol parameterizations of the atmosphere, several relatively large, but partly compensating, coding errors in the model's cloud, convection, and turbulence parameterizations were corrected. The representation of land processes was refined by introducing a multilayer soil hydrology scheme, extending the land biogeochemistry to include the nitrogen cycle, replacing the soil and litter decomposition model and improving the representation of wildfires. The ocean biogeochemistry now represents cyanobacteria prognostically in order to capture the response of nitrogen fixation to changing climate conditions and further includes improved detritus settling and numerous other refinements. As something new, in addition to limiting drift and minimizing certain biases, the instrumental record warming was explicitly taken into account during the tuning process. To this end, a very high climate sensitivity of around 7 K caused by low‐level clouds in the tropics as found in an intermediate model version was addressed, as it was not deemed possible to match observed warming otherwise. As a result, the model has a climate sensitivity to a doubling of CO2 over preindustrial conditions of 2.77 K, maintaining the previously identified highly nonlinear global mean response to increasing CO2 forcing, which nonetheless can be represented by a simple two‐layer model. %0 journal article %@ 1758-678X %A Morim, J., Hemer, M., Wang, X., Cartwright, N., Trenham, C., Semedo, A., Young, I., Bricheno, L., Camus, P., Casas-Prat, M., Erikson, L., Mentaschi, L., Mori, N., Shimura, T., Timmermans, B., Aarnes, O., Breivik, Ø., Behrens, A., Dobrynin, M., Menendez, M., Staneva, J., Wehner, M., Wolf, J., Kamranzad, B., Webb, A., Stopa, J., Andutta, F. %D 2019 %J Nature Climate Change %P 711-718 %R doi:10.1038/s41558-019-0542-5 %T Robustness and uncertainties in global multivariate wind-wave climate projections %U https://doi.org/10.1038/s41558-019-0542-5 %X Understanding climate-driven impacts on the multivariate global wind-wave climate is paramount to effective offshore/coastal climate adaptation planning. However, the use of single-method ensembles and variations arising from different methodologies has resulted in unquantified uncertainty amongst existing global wave climate projections. Here, assessing the first coherent, community-driven, multi-method ensemble of global wave climate projections, we demonstrate widespread ocean regions with robust changes in annual mean significant wave height and mean wave period of 5–15% and shifts in mean wave direction of 5–15°, under a high-emission scenario. Approximately 50% of the world’s coastline is at risk from wave climate change, with ~40% revealing robust changes in at least two variables. Furthermore, we find that uncertainty in current projections is dominated by climate model-driven uncertainty, and that single-method modelling studies are unable to capture up to ~50% of the total associated uncertainty. %0 journal article %@ 0169-555X %A Deng, J., Wu, J., Zhang, W., Dudzinska-Nowak, J., Harff, J. %D 2019 %J Geomorphology %P 365-376 %R doi:10.1016/j.geomorph.2018.11.018 %T Characterising the relaxation distance of nearshore submarine morphology: A southern Baltic Sea case study %U https://doi.org/10.1016/j.geomorph.2018.11.018 %X A method for defining the length of coast with alongshore uniformity of nearshore submarine morphology is required in many shore-normal, nearshore profile modelling approaches. Here, we introduce a new variable, the ‘relaxation distance’, to describe the alongshore spacing between two adjacent shore-normal profiles characterised by distinct morphologies. Within this distance, alongshore morphological changes are too small to distinguish, so the nearshore submarine morphology is regarded as uniform along the coast. We apply a semi-variogram approach, which expresses decreased spatial correlation of the nearshore submarine morphology with alongshore distance, to quantify relaxation distances. We apply this morphological variable to analyse 225 measured shore-normal submarine profiles at 500 m intervals in three distinct sites of the tideless, wave-dominated southern Baltic coast: Swina, Łeba, and Hel. The relaxation distances of these three sites are approximately 4500 m, 3000 m, and 2200 m. Of the three sites, Swina has the smoothest nearshore submarine morphology and the weakest wave energy. The relaxation distances of different quasi-straight segments at each site appear similar but those at different sites decrease with enlarged morphological perturbations, which are residuals resulting from detrending the shore-normal profiles. The standard deviations of these morphological perturbations are correlated with the incidence wave angles and wave energy. We also found that large perturbations (such as longshore bars and channels) have a significant impact on the estimation of underwater volume using shore-normal profile trends. Therefore, relaxation distance can indicate morphological smoothness, the length of shore-parallel uniform nearshore submarine morphology, and the impact of local processes on submarine morphology. %0 journal article %@ 2296-7745 %A De Mey-Frémaux, P., Ayoub, N., Barth, A., Brewin, R., Charria, G., Campuzano, F., Ciavatta, S., Cirano, M., Edwards, C.A., Federico, I., Gao, S., Hermosa, I.G., Sotillo, M.G., Hewitt, H., Hole, L.R., Holt, J., King, R., Kourafalou, V., Lu, Y., Mourre, B., Pascual, A., Staneva, J., Stanev, E.V., Wang, H., Zhu, X. %D 2019 %J Frontiers in Marine Science %P 436 %R doi:10.3389/fmars.2019.00436 %T Model-Observations Synergy in the Coastal Ocean %U https://doi.org/10.3389/fmars.2019.00436 %X Integration of observations of the coastal ocean continuum, from regional oceans to shelf seas and estuaries/deltas with models, can substantially increase the value of observations and enable a wealth of applications. In particular, models can play a critical role at connecting sparse observations, synthesizing them, and assisting the design of observational networks; in turn, whenever available, observations can guide coastal model development. Coastal observations should sample the two-way interactions between nearshore, estuarine and shelf processes and open ocean processes, while accounting for the different pace of circulation drivers, such as the fast atmospheric, hydrological and tidal processes and the slower general ocean circulation and climate scales. Because of these challenges, high-resolution models can serve as connectors and integrators of coastal continuum observations. Data assimilation approaches can provide quantitative, validated estimates of Essential Ocean Variables in the coastal continuum, adding scientific and socioeconomic value to observations through applications (e.g., sea-level rise monitoring, coastal management under a sustainable ecosystem approach, aquaculture, dredging, transport and fate of pollutants, maritime safety, hazards under natural variability or climate change). We strongly recommend an internationally coordinated approach in support of the proper integration of global and coastal continuum scales, as well as for critical tasks such as community-agreed bathymetry and coastline products. %0 journal article %@ 0930-7575 %A Schultze, M., Rockel, B. %D 2018 %J Climate Dynamics %N 9-10 %P 3331-3354 %R doi:10.1007/s00382-017-3808-5 %T Direct and semi-direct effects of aerosol climatologies on long-term climate simulations over Europe %U https://doi.org/10.1007/s00382-017-3808-5 9-10 %X This study compares the direct and semi-direct aerosol effects of different annual cycles of tropospheric aerosol loads for Europe from 1950 to 2009 using the regional climate model COSMO-CLM, which is laterally forced by reanalysis data and run using prescribed, climatological aerosol optical properties. These properties differ with respect to the analysis strategy and the time window, and are then used for the same multi-decadal period. Five simulations with different aerosol loads and one control simulation without any tropospheric aerosols are integrated and compared. Two common limitations of our simulation strategy, to fully assess direct and semi-direct aerosol effects, are the applied observed sea surface temperatures and sea ice conditions, and the lack of short-term variations in the aerosol load. Nevertheless, the impact of different aerosol climatologies on common regional climate model simulations can be assessed. The results of all aerosol-including simulations show a distinct reduction in solar irradiance at the surface compared with that in the control simulation. This reduction is strongest in the summer season and is balanced primarily by a weakening of turbulent heat fluxes and to a lesser extent by a decrease in longwave emissions. Consequently, the seasonal mean surface cooling is modest. The temperature profile responses are characterized by a shallow near-surface cooling and a dominant warming up to the mid-troposphere caused by aerosol absorption. The resulting stabilization of stratification leads to reduced cloud cover and less precipitation. A decrease in cloud water and ice content over Central Europe in summer possibly reinforce aerosol absorption and thus strengthen the vertical warming. The resulting radiative forcings are positive. The robustness of the results was demonstrated by performing a simulation with very strong aerosol forcing, which lead to qualitatively similar results. A distinct added value over the default aerosol setup of Tanré et al. (1984) was found in the simulations with more recent aerosol data sets for solar irradiance. The improvements are largest under low cloud conditions, while overestimated cloud cover in all setups causes a common underestimation of low and medium values of solar irradiance. In addition, the prevalent cold bias in the COSMO-CLM is reduced in winter and spring when using updated aerosol data. Our results emphasize the importance of semi-direct aerosol effects, especially over Central Europe in terms of changes in turbulent fluxes and changes in cloud properties. We also suggest to replace the default Tanré et al. (1984) aerosol climatology with more recent and realistic data sets. Thereby, a better model performance in comparison to observations can be achieved, or the masking of model shortcomings due to a too strong direct aerosol forcing thus far is prevented. %0 journal article %@ 1400-0350 %A Gerkensmeier, B., Ratter, B.M.W. %D 2018 %J Journal of Coastal Conservation %N 1 %P 145-156 %R doi:10.1007/s11852-016-0454-8 %T Multi-risk, multi-scale and multi-stakeholder – The contribution of a bow-tie analysis for risk management in the trilateral Wadden Sea Region %U https://doi.org/10.1007/s11852-016-0454-8 1 %X Risk management processes increasingly call for enhanced stakeholder participation, and aim to integrate different risk perceptions, concerns and interests. Frequently, this goal is driven by the increased complexity of risk management processes, as risk management processes continuously have to deal with multi-risk situations including impacts resulting from risks of natural hazards and risks caused by misguided social or economic development. Although stakeholder participation is required by different policies, major challenges still arise from the question of how to perform multi-stakeholder participation in practice. In order to find answers, we tested the so-called ‘bow-tie analysis’ as a potential tool to facilitate multi-stakeholder participation with a major effort on integrating stakeholders risk perceptions and interest in the risk management processes. The bow-tie analysis is a commonly used risk assessment technique (IEC 2009) to analyse cause-and-effect pathways of risks, but its application in multi-stakeholder processes in risk management of natural hazards, especially in a European context, is rather new. Using practical experiences from the trilateral Wadden Sea Region we demonstrate the bow-tie analysis’ contribution to coastal risk management processes in this coastal area by facilitating collaborative identification, comprehension and analysis of the management system. The use of a modified bow-tie analysis in collaboration with stakeholders from the Wadden Sea Region proved to be an appropriate framework for enhancing the understanding of risk management processes and fostered disclosure of different perceptions and concerns of multi-risk problematics. The bow-tie can be beneficial as a communication and co-construction tool in risk management processes in a multi-risk context. %0 journal article %@ 1616-7341 %A Teich, T., Groll, N., Weisse, R. %D 2018 %J Ocean Dynamics %N 11 %P 1559-1570 %R doi:10.1007/s10236-018-1210-4 %T Long-term statistics of potentially hazardous sea states in the North Sea 1958–2014 %U https://doi.org/10.1007/s10236-018-1210-4 11 %X Significant wave height and mean wave period are two of the most commonly used parameters to describe wave climate, wave climate variability, and their potential long-term changes. While these parameters are generally useful to characterize the distribution of waves within a given sea state, they provide less information about potentially high-risk situations. Over the recent years, a number of criteria were suggested that are considered to better characterize high-risk situations and which could bear a potential for the development of safety warning indices. Based on a multi-decadal high-resolution wind-wave hindcast, a climatology of such parameters is developed for the North Sea covering the years 1958–2014. More specifically, average conditions, inter-annual variability and long-term changes for unusually steep, rapidly developing and crossing sea states are considered. Generally, there are pronounced spatial variations in the frequency of such sea states, while over time, there is some seasonal and inter-annual variability but no substantial long-term trend could be identified. %0 journal article %@ 0079-6611 %A Cavaleri, L., Abdalla, S., Benetazzo, A., Bertotti, L., Bidlot, J.-R., Breivik, O., Carniel, S., Jensen, R.E., Portilla-Yandun, J., Rogers, W.E., Roland, A., Sanchez-Arcilla, A., Smith, J.M., Staneva, J., Toledo, Y., Vledder, G.Ph.van, Westhuysen, A.J. %D 2018 %J Progress in Oceanography %P 164-233 %R doi:10.1016/j.pocean.2018.03.010 %T Wave modelling in coastal and inner seas %U https://doi.org/10.1016/j.pocean.2018.03.010 %X In the long term development of the research on wind waves and their modelling, in particular of the inner and coastal seas, the present situation is framed with a short look at the past, a critical analysis of the present capabilities and a foresight of where the field is likely to go. After a short introduction, Chapter 2 deals with the basic processes at work and their modelling aspects. Chapter 3 highlights the interaction with wind and currents. Chapter 4 stresses the need for a more complete, spectral, approach in data assimilation. Chapter 5 summarizes the situation with a discussion on the present status in wave modelling and a look at what we can expect in the future. %0 journal article %@ 0930-7575 %A Yi, X., Huenicke, B., Tim, N., Zorita, E. %D 2018 %J Climate Dynamics %N 1-2 %P 201-213 %R doi:10.1007/s00382-017-3599-8 %T The relationship between Arabian Sea upwelling and Indian Monsoon revisited in a high resolution ocean simulation %U https://doi.org/10.1007/s00382-017-3599-8 1-2 %X Studies based on sediment records, sea-surface temperature and wind suggest that upwelling along the western coast of Arabian Sea is strongly affected by the Indian summer Monsoon. We examine this relationship directly in an eddy-resolving global ocean simulation STORM driven by atmospheric reanalysis over the last 61 years. With its very high spatial resolution (10 km), STORM allows us to identify characteristics of the upwelling system. We analyse the co-variability between upwelling and meteorological and oceanic variables from 1950 to 2010. The analysis reveals high interannual correlations between coastal upwelling and along-shore wind-stress (r = 0.73) as well as with sea-surface temperature (r = −0.83). However, the correlation between the upwelling and the Monsoon is small. We find an atmospheric circulation pattern different from the one that drives the Monsoon as the main modulator of the upwelling variability. In spite of this, the patterns of temperature anomalies that are either linked to Arabian Sea upwelling or to the Monsoon are spatially quite similar, although the physical mechanisms of these links are different. In addition, no long-term trend is detected in our modelled upwelling in the Arabian Sea. %0 journal article %@ 1616-7341 %A Ganske, A., Fery, N., Gaslikova, L., Grabemann, I., Weisse, R., Tinz, B. %D 2018 %J Ocean Dynamics %N 10 %P 1371-1382 %R doi:10.1007/s10236-018-1190-4 %T Identification of extreme storm surges with high-impact potential along the German North Sea coastline %U https://doi.org/10.1007/s10236-018-1190-4 10 %X Planning and design of coastal protection rely on information about the probabilities of very severe storm tides and the possible changes that may occur in the course of climate change. So far, this information is mostly provided in the form of high percentiles obtained from frequency distributions or return values. More detailed information and assessments of events that may cause extreme damages or have extreme consequences at the coast are so far still unavailable. We describe and compare two different approaches that may be used to identify highly unlikely but still physically possible and plausible events from model simulations. Firstly, in the case when consistent wind and tide-surge data are available, different metrics such as the height of the storm surge can be derived directly from the simulated water levels. Secondly, in cases where only atmospheric data are available, the so called effective wind may be used. The latter is the projection of the horizontal wind vector on that direction which is most effective in producing surges at the coast. Comparison of events identified by both methods show that they can identify extreme events but that knowledge of the effective wind alone does not provide sufficient information to identify the highest storm surges. Tracks of the low-pressure systems over the North Sea need to be investigated to find those cases, where the duration of the high wind is too short to induce extreme storm tides. On the other hand, factors such as external surges or variability in mean sea level may enhance surge heights and are not accounted for in estimates based on effective winds only. Results from the analysis of an extended data set suggest that unprecedented storm surges at the German North Sea coast are possible even without taking effects from rising mean sea level into account. The work presented is part of the ongoing project “Extreme North Sea Storm Surges and Their Consequences” (EXTREMENESS) and represents the first step towards an impact assessment for very severe storm surges which will serve as a basis for development of adaptation options and evaluation criteria. %0 journal article %@ 2169-9275 %A Pein, J., Valle-Levinson, A., Stanev, E.V. %D 2018 %J Journal of Geophysical Research : Oceans %N 3 %P 1670-1683 %R doi:10.1002/2016JC012623 %T Secondary Circulation Asymmetry in a Meandering, Partially Stratified Estuary %U https://doi.org/10.1002/2016JC012623 3 %X Numerical model experiments are used to study the effects of multiple channel bends on estuarine dynamics and, in particular, on secondary flows. These effects are demonstrated by comparing experiments with two different idealized trumpet‐shaped estuaries, one straight and another one with a ∼8 km meandering section in the middle of the estuary. Meanders complicate the flow field by introducing secondary processes. For instance, meanders increase turbulence and associated mixing locally within the water column, as well as outside the meandering portion. Furthermore, meanders transform up to 30% of the along‐channel momentum into secondary circulation. Production of turbulence and secondary currents is different at flood and ebb tidal phases. At flood, meanders lead to unstable stratification and increased turbulence. At ebb, the flow develops a helical pattern and adjusts to the channel curvature with minimal decrease in density stability. The secondary circulation asymmetry is caused by an interplay between the across‐channel baroclinic pressure gradient force and the centrifugal force. During ebb both forces enhance each other, whereas they oppose during flood. As a consequence of this interaction between baroclinic forcing and curving morphology, ebb flows and horizontal buoyancy fluxes increase relative to flood. The enhanced ebb dominance shifts a density front toward the mouth of the estuary, thus reducing salt intrusion. %0 journal article %@ 1941-7012 %A Djath, B., Schulz-Stellenfleth, J., Canadillas, B. %D 2018 %J Journal of Renewable and Sustainable Energy %N 4 %P 043301 %R doi:10.1063/1.5020437 %T Impact of atmospheric stability on X-band and C-band synthetic aperture radar imagery of offshore windpark wakes %U https://doi.org/10.1063/1.5020437 4 %X C-band and X-band Synthetic Aperture Radar (SAR) data acquired by the Sentinel-1 and TerraSAR-X satellites are used to study atmospheric wakes behind offshore wind parks in the German Bight. A particular focus is on the impact of atmospheric stability on wake parameters like the wake length. Stability parameters are estimated from measurements taken at the FINO-1 observation platform. Based on a data set covering different seasons and concentrating on the first German offshore wind park Alpha Ventus (AV), it is shown that in this area stable atmospheric conditions favour longer wakes. This is first demonstrated for situations, where the wake behind AV was unperturbed by other neighbor wind parks. In this case, wakes of more than 30 km length are observed. In a second step, the more complicated situation with wake superposition from different neighboring wind parks is analysed. It is shown that in this case, the merged wakes can extend to more than 70 km downstream.The analysis is challenged by two factors. First of all, the FINO-1 platform is within the wind farm wakes for a certain range of wind directions. This means stability estimates for the upstream conditions are not straightforward to obtain in these conditions. The second complication is associated with an apparent increase in the radar cross section downstream of wind parks observed on many SAR scenes, typically within the first 10 km downstream the wind park. A semi-empirical model is proposed to explain this effect by an increased downward momentum flux associated with increased turbulence generated by the wind park. Applying numerical inversion methods, a couple of typical downstream wind speed profiles are reproduced with this model based on SAR derived estimates of the friction velocity. %0 journal article %@ 0962-8452 %A Michels, J., Stippkugel, A., Lenz, M., Wirtz, K., Engel, A. %D 2018 %J Proceedings of the Royal Society B %N 1885 %P 20181203 %R doi:10.1098/rspb.2018.1203 %T Rapid aggregation of biofilm-covered microplastics with marine biogenic particles %U https://doi.org/10.1098/rspb.2018.1203 1885 %X Ocean plastic pollution has resulted in a substantial accumulation of microplastics in the marine environment. Today, this plastic litter is ubiquitous in the oceans, including even remote habitats such as deep-sea sediments and polar sea ice, and it is believed to pose a threat to ecosystem health. However, the concentration of microplastics in the surface layer of the oceans is considerably lower than expected, given the ongoing replenishment of microplastics and the tendency of many plastic types to float. It has been hypothesized that microplastics leave the upper ocean by aggregation and subsequent sedimentation. We tested this hypothesis by investigating the interactions of microplastics with marine biogenic particles collected in the southwestern Baltic Sea. Our laboratory experiments revealed a large potential of microplastics to rapidly coagulate with biogenic particles, which substantiates this hypothesis. Together with the biogenic particles, the microplastics efficiently formed pronounced aggregates within a few days. The aggregation of microplastics and biogenic particles was significantly accelerated by microbial biofilms that had formed on the plastic surfaces. We assume that the demonstrated aggregation behaviour facilitates the export of microplastics from the surface layer of the oceans and plays an important role in the redistribution of microplastics in the oceans. %0 journal article %@ 0308-597X %A Hassler, B., Gee, K., Gilek, M., Luttmann, A., Morf, A., Saunders, F., Stalmokaite, I., Strand, H., Zaucha, J. %D 2018 %J Marine Policy %P 138-147 %R doi:10.1016/j.marpol.2018.03.002 %T Collective action and agency in Baltic Sea marine spatial planning: Transnational policy coordination in the promotion of regional coherence %U https://doi.org/10.1016/j.marpol.2018.03.002 %X marine spatial planning governance, these two governance components need to be brought together to improve consistency between regional alignment and to enhance opportunities for countries to collaborate at lower levels. Issue-specific transnational working groups or workshops can be one way to identify and act upon such potential synergies. %0 journal article %@ 2073-4433 %A Storch, H.v., Cavicchia, L., Feser, F., Li, D. %D 2018 %J Atmosphere %N 9 %P 337 %R doi:10.3390/atmos9090337 %T The Concept of Large-Scale Conditioning of Climate Model Simulations of Atmospheric Coastal Dynamics: Current State and Perspectives %U https://doi.org/10.3390/atmos9090337 9 %X We review the state of dynamical downscaling with scale-constrained regional and global models. The methodology, in particular spectral nudging, has become a routine and well-researched tool for hindcasting climatologies of sub-synoptic atmospheric disturbances in coastal regions. At present, the spectrum of applications is expanding to other phenomena, but also to ocean dynamics and to extended forecasting. Additionally, new diagnostic challenges are appearing such as spatial characteristics of small-scale phenomena such as Low Level Jets. %0 journal article %@ 0930-7575 %A Barcikowska, M.J., Kapnick, S.B., Feser, F. %D 2018 %J Climate Dynamics %N 5-6 %P 2039-2059 %R doi:10.1007/s00382-017-3735-5 %T Impact of large-scale circulation changes in the North Atlantic sector on the current and future Mediterranean winter hydroclimate %U https://doi.org/10.1007/s00382-017-3735-5 5-6 %X The Mediterranean region, located in the transition zone between the dry subtropical and wet European mid-latitude climate, is very sensitive to changes in the global mean climate state. Projecting future changes of the Mediterranean hydroclimate under global warming therefore requires dynamic climate models to reproduce the main mechanisms controlling regional hydroclimate with sufficiently high resolution to realistically simulate climate extremes. To assess future winter precipitation changes in the Mediterranean region we use the Geophysical Fluid Dynamics Laboratory high-resolution general circulation model for control simulations with pre-industrial greenhouse gas and aerosol concentrations which are compared to future scenario simulations. Here we show that the coupled model is able to reliably simulate the large-scale winter circulation, including the North Atlantic Oscillation and Eastern Atlantic patterns of variability, and its associated impacts on the mean Mediterranean hydroclimate. The model also realistically reproduces the regional features of daily heavy rainfall, which are absent in lower-resolution simulations. A five-member future projection ensemble, which assumes comparatively high greenhouse gas emissions (RCP8.5) until 2100, indicates a strong winter decline in Mediterranean precipitation for the coming decades. Consistent with dynamical and thermodynamical consequences of a warming atmosphere, derived changes feature a distinct bipolar behavior, i.e. wetting in the north—and drying in the south. Changes are most pronounced over the northwest African coast, where the projected winter precipitation decline reaches 40% of present values. Despite a decrease in mean precipitation, heavy rainfall indices show drastic increases across most of the Mediterranean, except the North African coast, which is under the strong influence of the cold Canary Current. %0 journal article %@ 2077-1312 %A Semedo, A., Dobrynin, M., Lemos, G., Behrens, A., Staneva, J., de Vries, H., Sterl, A., Bidlot, J.-R., Miranda, P.M.A., Murawski, J. %D 2018 %J Journal of Marine Science and Engineering %N 3 %P 90 %R doi:10.3390/jmse6030090 %T CMIP5-Derived Single-Forcing, Single-Model, and Single-Scenario Wind-Wave Climate Ensemble: Configuration and Performance Evaluation %U https://doi.org/10.3390/jmse6030090 3 %X A Coupled Model Intercomparison Project Phase 5 (CMIP5)-derived single-forcing, single-model, and single-scenario dynamic wind-wave climate ensemble is presented, and its historic period (1979–2005) performance in representing the present wave climate is evaluated. A single global climate model (GCM)-forcing wave climate ensemble was produced with the goal of reducing the inter GCM variability inherent in using a multi-forcing approach for the same wave model. Seven CMIP5 EC-Earth ensemble runs were used to force seven WAM wave model realizations, while future wave climate simulations, not analyzed here, were produced using a high-emission representative concentration pathway 8.5 (RCP8.5) set-up. The wave climate ensemble’s historic period was extensively compared against a set of 72 in situ wave-height observations, as well as to ERA-Interim reanalysis and Climate Forecast System Reanalysis (CFSR) hindcast. The agreement between the wave climate ensemble and the in situ measurements and reanalysis of mean and extreme wave heights, mean wave periods, and mean wave directions was good, in line with previous studies or even better in some areas of the global ocean, namely in the extratropical latitudes. These results give a good degree of confidence in the ability of the ensemble to simulate a realistic climate change signal. %0 journal article %@ 2190-4979 %A Barcikowska, M.J., Weaver, S.J., Feser, F., Russo, S., Schenk, F., Stone, D.A., Zahn, M. %D 2018 %J Earth System Dynamics %N 2 %P 679-699 %R doi:10.5194/esd-9-679-2018 %T Euro-Atlantic winter storminess and precipitation extremes under 1.5 °C vs. 2 °C warming scenarios %U https://doi.org/10.5194/esd-9-679-2018 2 %X Regions impacted by the strengthening of the midlatitude jet, such as the northwest coasts of British Isles, Scandinavia and the Norwegian Sea, and over the North Atlantic east from Newfoundland experience an increase in the mean as well as daily and sub daily precipitation and wind extremes and storminess suggesting an important influence of increasing storm activity in these regions in response to global warming. %0 journal article %@ 0272-7714 %A Nasermoaddeli, M.H., Lemmen, C., Stigge, G., Kerimoglu, O., Burchard, H., Klingbeil, K., Hofmeister, R., Kreus, M., Wirtz, K.W., Koesters, F. %D 2018 %J Estuarine, Coastal and Shelf Science %P 62-76 %R doi:10.1016/j.ecss.2017.11.002 %T A model study on the large-scale effect of macrofauna on the suspended sediment concentration in a shallow shelf sea %U https://doi.org/10.1016/j.ecss.2017.11.002 %X The activity of macrofauna on the sea floor is since long known to mediate deposition and erosion of sediment, but so far most studies addressed this effect at a local scale. In the present paper, the contribution of the observed macrofauna distribution (exemplified by a bivalve, the bean-like tellin Fabulina fabula, formerly known as Tellina fabula) on large-scale sediment transport in the southern North Sea is investigated by means of a model study. Macrofauna effects are considered with respect to the critical bed shear stress and erodibility, which are two important factors that control the resuspension rate. Simulation results for a typical winter month revealed for the first time that the suspended sediment concentration (SSC) is increased not only locally but beyond the inhabited zones. This alteration is not confined to near-bed zones but can be observed throughout the entire water column, especially during storm events. These effects are most prominent in the fine silt fraction, coarser and finer fractions are less affected. For a selected storm event in February 2010, we explain the counter-intuitive decrease in near-bed SSC in some areas with a high macrofauna abundance compared to a simulation excluding such macrofauna: A high macrofauna-induced entrainment rate leads to rapid exhaustion of available sediments at the bed in the model and consequently limits the near-bed SSC. %0 journal article %@ 2299-3835 %A Schaaf, B., Feser, F. %D 2018 %J Meteorology, Hydrology and Water Management %N 2 %P 21-37 %R doi:10.26491/mhwm/85507 %T Is there added value of convection-permitting regional climate model simulations for storms over the German Bight and Northern Germany? %U https://doi.org/10.26491/mhwm/85507 2 %X This study tackles the question: Do very high-resolution convective-permitting regional climate model (RCM) simulations add value compared to coarser RCM runs for certain extreme weather conditions, namely strong wind and storm situations? Ten strong storm cases of the last two decades were selected and dynamically downscaled with the RCM COSMO-CLM (24 and 2.8 km grid point distance). These cyclones crossed the high-resolution model domain, which encompasses the German Bight, Northern Germany, and parts of the Baltic Sea. One storm case study (storm Christian of October 2013) is discussed in more detail in order to analyze the small-scale storm features and the associated potential added value of the high-resolution simulation. The results indicate an added value for atmospheric dynamical processes such as convective precipitation or post-frontal cloud cover. The multiple storm analysis revealed added value for the high-resolution regional climate simulation for 10 m wind speed, mean sea level pressure, and total cloud cover for most storms which were examined, but the improvements are small. Wind direction and precipitation were already well simulated by the coarser RCM and the higher resolution could often not add any value for these variables. The analysis showed that the added value is more distinct for the synoptic comparisons than for the multiple storm study analyzed with statistical measures like the Brier Skill Score. %0 journal article %@ 1400-0350 %A Evadzi, P.I.K., Scheffran, J., Zorita, E., Huenicke, B. %D 2018 %J Journal of Coastal Conservation %N 1 %P 183-197 %R doi:10.1007/s11852-017-0569-6 %T Awareness of sea-level response under climate change on the coast of Ghana %U https://doi.org/10.1007/s11852-017-0569-6 1 %X In response to climate change, coastal communities are expected to experience increasing coastal impacts of sea-level rise (SLR). Strategies formulated and implemented to curb these impacts can thus be more effective if scientific findings on the response to climate change and SLR impacts on coastal communities are taken into consideration and not based merely on the need for coastal protection due to physical coastal erosion. There is also the need to determine the level of awareness of sea-level rise and responses in coastal communities to improve adaptation planning. This study assesses the impact of future erosion on the coastal land cover of Ghana. This assessment estimates approximately 2.66 km2, 2.77 km2, and 3.24 km2 of coastal settlements, 2.10 km2, 2.20 km2 and 2.58 km2 of lagoons, 1.39 km2, 1.46 km2 and 1.71 km2 of wetlands to be at risk of inundation by the year 2050 based on coastal erosion estimates for the 2.6, 4.5 and 8.5 Representative Concentration Pathways (RCPs) used in the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC). This study also assesses the level of awareness of respondents to SLR on the coast of Ghana and explores the availability and level of integration of scientific knowledge of SLR into coastal adaptation strategies in Ghana. Assessment of the awareness of SLR responses to the changing climate in Ghana is made through semi-structured interviews at national, municipal/district and coastal community scales. Although settlements may be inundated based on the coastal erosion estimates, coastal dwellers interviewed cherish their proximity to the sea and are determined to maintain their occupancy close to the sea as spatial location influences their source of livelihood (fishing). Respondents lack knowledge/understanding of SLR, as the majority of household interviewees attributed the rise or fall in sea level to God. Respondents from Ngiresia alleged that the ongoing coastal sea defence project in their community has led to increased malaria cases. %0 journal article %@ 0930-7575 %A Barkhordarian, A., Storch, H.v., Zorita, E., Loikith, P.C., Mechoso, C.R. %D 2018 %J Climate Dynamics %N 5-6 %P 1901-1914 %R doi:10.1007/s00382-017-3988-z %T Observed warming over northern South America has an anthropogenic origin %U https://doi.org/10.1007/s00382-017-3988-z 5-6 %X We investigate whether the recently observed trends in daily maximum and minimum near-surface air temperature (Tmax and Tmin, respectively) over South America (SA) are consistent with the simulated response of Tmin and Tmax to anthropogenic forcing. Results indicate that the recently observed warming in the dry seasons is well beyond the range of natural (internal) variability. In the wet season the natural modes of variability explain a substantial portion of Tmin and Tmax variability. We demonstrate that the large-scale component of greenhouse gas (GHG) forcing is detectable in dry-seasonal warming. However, none of the global and regional climate change projections reproduce the observed warming of up to 0.6 K/Decade in Tmax in 1983–2012 over northern SA during the austral spring (SON). Thus, besides the global manifestation of GHG forcing, other external drivers have an imprint. Using aerosols-only forcing simulations, our results provide evidence that anthropogenic aerosols also have a detectable influence in SON and that the indirect effect of aerosols on cloud’s lifetime is more compatible with the observed record. In addition, there is an increasing trend in the observed incoming solar radiation over northern SA in SON, which is larger than expected from natural (internal) variability alone. We further show that in the dry seasons the spread of projected trends based on the RCP4.5 scenario derived from 30 CMIP5 models encompasses the observed area-averaged trends in Tmin and Tmax. This may imply that the observed excessive warming in the dry seasons serve as an illustration of plausible future expected change in the region. %0 journal article %@ 2190-4979 %A Karabil, S., Zorita, E., Huenicke, B. %D 2018 %J Earth System Dynamics %N 1 %P 69-90 %R doi:10.5194/esd-9-69-2018 %T Contribution of atmospheric circulation to recent off-shore sea-level variations in the Baltic Sea and the North Sea %U https://doi.org/10.5194/esd-9-69-2018 1 %X We investigated, and when possible quantified, the contribution of several physical mechanisms which may explain the link between the sea-level variability and the atmospheric pattern described by the BANOS-index. These mechanisms include the inverse barometer effect (IBE), fresh water balance, net energy flux and wind-induced water transport. We found that the most important mechanisms are the IBE in both wintertime and summertime. Assuming a complete equilibration of seasonal sea-level to the SLP gradients over this region, at seasonal time scales the IBE can explain up to 88 % of the sea-level variability attributed to the BANOS-index in wintertime and 34% in summertime. The net energy flux at the surface is found to be an important factor for the variation of sea-level, explaining 35 % of sea-level variance in wintertime and a very small amount in summer. The freshwater flux could only explain 27 % of the variability in summertime and a negligible part in winter. In contrast to the NAO, the direct wind forcing associated to the SLP BANOS pattern does not lead to transport of water from the North Sea into the Baltic Sea in wintertime. Keywords: off-shore sea-level, atmospheric factors, the Baltic Sea, the North Sea, statistical analysis. %0 journal article %@ 1462-9011 %A Gerkensmeier, B., Ratter, B.M.W. %D 2018 %J Environmental Science & Policy %P 144-151 %R doi:10.1016/j.envsci.2017.11.011 %T Governing coastal risks as a social process - Facilitating integrative risk management by enhanced multi-stakeholder collaboration %U https://doi.org/10.1016/j.envsci.2017.11.011 %X By proposing an Integrated Risk Management Approach (IRMA) we contribute to simplified conditions in the transfer from scientific debates into practical implementation. Looking in particular on coastal regions, IRMA focus the user’s view on the essential challenges in terms of enhanced multi-sectoral structures and improved social and flexible processes, as much as it gives advice on its methodical realization. Using our practical experiences in the trilateral Wadden Sea Region, we disclose IRMA’s contribution on enhanced consideration of historical framing, risk perceptions, risk awareness and enhanced multi-stakeholder participation. Multi-stakeholder participation, institutionalised in multi-stakeholder partnerships, makes an essential contribution towards enhanced collaborative processes between scientists, policy-makers and affected communities. %0 journal article %@ 0965-3562 %A Gerkensmeier, B., Ratter, B.M.W., Vollmer, M., Walsh, C. %D 2018 %J Disaster Prevention and Management %N 1 %P 15-27 %R doi:10.1108/DPM-04-2017-0074 %T Managing coastal risks at the Wadden Sea: a societal perspective %U https://doi.org/10.1108/DPM-04-2017-0074 1 %X In this context, the trilateral dimension, discussed here for the first time in relation with coastal risk management processes in the WSR, is emphasized as an efficient level that offers room for enhanced participatory and negotiation processes that are crucial for enhanced risk management processes. %0 journal article %@ 2190-4979 %A Lauer, A., Jones, C., Eyring, V., Evaldsson, M., Hagemann, S., Maekelae, J., Martin, G., Roehrig, R., Wang, S. %D 2018 %J Earth System Dynamics %N 1 %P 33-67 %R doi:10.5194/esd-9-33-2018 %T Process-level improvements in CMIP5 models and their impact on tropical variability, the Southern Ocean, and monsoons %U https://doi.org/10.5194/esd-9-33-2018 1 %X The analysis shows that the tropical precipitation in three out of four models is clearly improved. Two of three updated coupled models show an improved representation of tropical sea surface temperatures with one coupled model not exhibiting a double Intertropical Convergence Zone (ITCZ). Simulated cloud amounts and cloud–radiation interactions are improved over the Southern Ocean. Improvements are also seen in the simulation of the SAM and WAM, although systematic biases remain in regional details and the timing of monsoon rainfall. Analysis of simulations with EC-Earth at different horizontal resolutions from T159 up to T1279 shows that the synoptic-scale variability in precipitation over the SAM and WAM regions improves with higher model resolution. The results suggest that the reasonably good agreement of modeled and observed mean WAM and SAM rainfall in lower-resolution models may be a result of unrealistic intensity distributions. %0 journal article %@ 0930-7575 %A Vrese, P.de, Hagemann, S. %D 2018 %J Climate Dynamics %N 5-6 %P 2023-2038 %R doi:10.1007/s00382-017-3996-z %T Uncertainties in modelling the climate impact of irrigation %U https://doi.org/10.1007/s00382-017-3996-z 5-6 %X Irrigation-based agriculture constitutes an essential factor for food security as well as fresh water resources and has a distinct impact on regional and global climate. Many issues related to irrigation’s climate impact are addressed in studies that apply a wide range of models. These involve substantial uncertainties related to differences in the model’s structure and its parametrizations on the one hand and the need for simplifying assumptions for the representation of irrigation on the other hand. To address these uncertainties, we used the Max Planck Institute for Meteorology’s Earth System model into which a simple irrigation scheme was implemented. In order to estimate possible uncertainties with regard to the model’s more general structure, we compared the climate impact of irrigation between three simulations that use different schemes for the land-surface–atmosphere coupling. Here, it can be shown that the choice of coupling scheme does not only affect the magnitude of possible impacts but even their direction. For example, when using a scheme that does not explicitly resolve spatial subgrid scale heterogeneity at the surface, irrigation reduces the atmospheric water content, even in heavily irrigated regions. Contrarily, in simulations that use a coupling scheme that resolves heterogeneity at the surface or even within the lowest layers of the atmosphere, irrigation increases the average atmospheric specific humidity. A second experiment targeted possible uncertainties related to the representation of irrigation characteristics. Here, in four simulations the irrigation effectiveness (controlled by the target soil moisture and the non-vegetated fraction of the grid box that receives irrigation) and the timing of delivery were varied. The second experiment shows that uncertainties related to the modelled irrigation characteristics, especially the irrigation effectiveness, are also substantial. In general the impact of irrigation on the state of the land surface is more than three times larger when assuming a low irrigation effectiveness than when a high effectiveness is assumed. For certain variables, such as the vertically integrated water vapour, the impact is almost an order of magnitude larger. The timing of irrigation also has non-negligible effects on the simulated climate impacts and it can strongly alter their seasonality. %0 journal article %@ 0094-8276 %A Bunzel, F., Mueller, W.A., Dobrynin, M., Froehlich, K., Hagemann, S., Pohlmann, H., Stacke, T., Baehr, J. %D 2018 %J Geophysical Research Letters %N 1 %P 346-353 %R doi:10.1002/2017GL076204 %T Improved Seasonal Prediction of European Summer Temperatures With New Five-Layer Soil-Hydrology Scheme %U https://doi.org/10.1002/2017GL076204 1 %X We evaluate the impact of a new five-layer soil-hydrology scheme on seasonal hindcast skill of 2 m temperatures over Europe obtained with the Max Planck Institute Earth System Model (MPI-ESM). Assimilation experiments from 1981 to 2010 and 10-member seasonal hindcasts initialized on 1 May each year are performed with MPI-ESM in two soil configurations, one using a bucket scheme and one a new five-layer soil-hydrology scheme. We find the seasonal hindcast skill for European summer temperatures to improve with the five-layer scheme compared to the bucket scheme and investigate possible causes for these improvements. First, improved indirect soil moisture assimilation allows for enhanced soil moisture-temperature feedbacks in the hindcasts. Additionally, this leads to improved prediction of anomalies in the 500 hPa geopotential height surface, reflecting more realistic atmospheric circulation patterns over Europe. %0 journal article %@ 2169-897X %A Zahn, M., Akperov, M., Rinke, A., Feser, F., Mokhov, I.I. %D 2018 %J Journal of Geophysical Research : Atmospheres %N 5 %P 2737-2751 %R doi:10.1002/2017JD027439 %T Trends of Cyclone Characteristics in the Arctic and Their Patterns From Different Reanalysis Data %U https://doi.org/10.1002/2017JD027439 5 %X Cyclones in the Arctic are detected and tracked in four different reanalysis data sets from 1981 to 2010. In great detail the spatial and seasonal patterns of changes are scrutinized with regards to their frequencies, depths, and sizes. We find common spatial patterns for their occurrences, with centers of main activity over the seas in winter, and more activity over land and over the North Pole in summer. The deep cyclones are more frequent in winter, and the number of weak cyclones peaks in summer. Overall, we find a good agreement of our tracking results across the different reanalyses. Regarding the frequency changes, we find strong decreases in the Barents Sea and along the Russian coast toward the North Pole and increases over most of the central Arctic Ocean and toward the Pacific in winter. Areas of increasing and decreasing frequencies are of similar size in winter. In summer there is a longish region of increase from the Laptev Sea toward Greenland, over the Canadian archipelago, and over some smaller regions west of Novaya Zemlya and over the Russia. The larger part of the Arctic experiences a frequency decrease. All the summer changes are found statistically unrelated to the winter patterns. In addition, the frequency changes are found unrelated to changes in cyclone depth and size. There is generally good agreement across the different reanalyses in the spatial patterns of the trend sign. However, the magnitudes of changes in a particular region may strongly differ across the data. %0 journal article %@ 1752-0894 %A Jiskra, M., Sonke, J.E., Obrist, D., Bieser, J., Ebinghaus, R., Myhre, C.L., Pfaffhuber, K.A., Waengberg, I., Kylloenen, K., Worthy, D., Martin, L.G., Labuschagne, C., Mkololo, T., Ramonet, M., Magand, O., Dommergue, A. %D 2018 %J Nature Geoscience %P 244-250 %R doi:10.1038/s41561-018-0078-8 %T A vegetation control on seasonal variations in global atmospheric mercury concentrations %U https://doi.org/10.1038/s41561-018-0078-8 %X Anthropogenic mercury emissions are transported through the atmosphere as gaseous elemental mercury (Hg(0)) before they are deposited to Earth’s surface. Strong seasonality in atmospheric Hg(0) concentrations in the Northern Hemisphere has been explained by two factors: anthropogenic Hg(0) emissions are thought to peak in winter due to higher energy consumption, and atmospheric oxidation rates of Hg(0) are faster in summer. Oxidation-driven Hg(0) seasonality should be equally pronounced in the Southern Hemisphere, which is inconsistent with observations of constant year-round Hg(0) levels. Here, we assess the role of Hg(0) uptake by vegetation as an alternative mechanism for driving Hg(0) seasonality. We find that at terrestrial sites in the Northern Hemisphere, Hg(0) co-varies with CO2, which is known to exhibit a minimum in summer when CO2 is assimilated by vegetation. The amplitude of seasonal oscillations in the atmospheric Hg(0) concentration increases with latitude and is larger at inland terrestrial sites than coastal sites. Using satellite data, we find that the photosynthetic activity of vegetation correlates with Hg(0) levels at individual sites and across continents. We suggest that terrestrial vegetation acts as a global Hg(0) pump, which can contribute to seasonal variations of atmospheric Hg(0), and that decreasing Hg(0) levels in the Northern Hemisphere over the past 20 years can be partly attributed to increased terrestrial net primary production. %0 journal article %@ 1991-959X %A Lemmen, C., Hofmeister, R., Klingbeil, K., Nasermoaddeli, H.M., Kerimoglu, O., Burchard, H., Koesters, F., Wirtz, K.W. %D 2018 %J Geoscientific Model Development %N 3 %P 915-935 %R doi:10.5194/gmd-11-915-2018 %T Modular System for Shelves and Coasts (MOSSCO v1.0) – a flexible and multi-component framework for coupled coastal ocean ecosystem modelling %U https://doi.org/10.5194/gmd-11-915-2018 3 %X Shelf and coastal sea processes extend from the atmosphere through the water column and into the sea bed. These processes are driven by physical, chemical, and biological interactions at local scales, and they are influenced by transport and cross strong spatial gradients. The linkages between domains and many different processes are not adequately described in current model systems. Their limited integration level in part reflects lacking modularity and flexibility; this shortcoming hinders the exchange of data and model components and has historically imposed supremacy of specific physical driver models. We here present the Modular System for Shelves and Coasts (MOSSCO, http://www.mossco.de), a novel domain and process coupling system tailored – but not limited – to the coupling challenges of and applications in the coastal ocean. MOSSCO builds on the existing coupling technology Earth System Modeling Framework and on the Framework for Aquatic Biogeochemical Models, thereby creating a unique level of modularity in both domain and process coupling; the new framework adds rich metadata, flexible scheduling, configurations that allow several tens of models to be coupled, and tested setups for coastal coupled applications. That way, MOSSCO addresses the technology needs of a growing marine coastal Earth System community that encompasses very different disciplines, numerical tools, and research questions. %0 journal article %@ 2169-8961 %A Meyer, M., Paetsch, J., Geyer, B., Thomas, H. %D 2018 %J Journal of Geophysical Research : Biogeosciences %N 5 %P 1511-1525 %R doi:10.1029/2017JG004281 %T Revisiting the Estimate of the North Sea Air-Sea Flux of CO2 in 2001/2002: The Dominant Role of Different Wind Data Products %U https://doi.org/10.1029/2017JG004281 5 %X For the North Sea, a semi‐enclosed shelf sea in the north‐eastern North Atlantic, the seasonal and annual CO2 air‐sea fluxes (ASF) had been estimated for 2001 and 2002 in earlier work. The underlying observations, ∆pCO2, salinity and temperature had been combined with 6‐hourly wind data derived from ERA40 reanalysis. In order to assess the impact of different wind data products on the computation of CO2 air‐sea fluxes, we compared ERA40 wind data with coastDat data derived from the non‐hydrostatic regional climate model COSMO‐CLM. From the four observational months September, November, February, and May all but the May‐data show higher wind speeds for coastDat than for ERA40, especially off the Norwegian, UK and continental coasts. Largest differences occur in the northern off‐shore areas. The comparison with observed wind data supports this feature generally: At Helgoland, an island in the German Bight, and at the Belgium pile “Westhinder” the ERA40 data underestimate both, the coastDat data and the observations. Wind observations for two Norwegian North Sea platforms were available: At the northern station “Troll” off the Norwegian coast the coastDat data overestimate the observations in winter. At “Ekofisk” in the central North Sea the ERA40 data fit the observations well while the coastDat data slightly overestimate the observational data in all months but in May. The corresponding CO2 ASF estimates show strongest deviations off the Norwegian coast. Using different bulk formulas for determining the net annual ASF resulted in differences due to different wind products of up to 34%. %0 journal article %@ 0300-7839 %A Xoplaki, E., Luterbacher, J., Wagner, S., Zorita, E., Fleitmann, D., Preiser-Kapeller, J., Sargent, A.M., White, S., Toreti, A., Haldon, J.F., Mordechai, L., Bozkurt, D., Akcer-Oen, S., Izdebski, A. %D 2018 %J Human Ecology %N 3 %P 363-379 %R doi:10.1007/s10745-018-9995-9 %T Modelling Climate and Societal Resilience in the Eastern Mediterranean in the Last Millennium %U https://doi.org/10.1007/s10745-018-9995-9 3 %X This article analyses high-quality hydroclimate proxy records and spatial reconstructions from the Central and Eastern Mediterranean and compares them with two Earth System Model simulations (CCSM4, MPI-ESM-P) for the Crusader period in the Levant (1095–1290 CE), the Mamluk regime in Transjordan (1260–1516 CE) and the Ottoman crisis and Celâlî Rebellion (1580–1610 CE). During the three time intervals, environmental and climatic stress tested the resilience of complex societies. We find that the multidecadal precipitation and drought variations in the Central and Eastern Mediterranean cannot be explained by external forcings (solar variations, tropical volcanism); rather they were driven by internal climate dynamics. Our research emphasises the challenges, opportunities and limitations of linking proxy records, palaeoreconstructions and model simulations to better understand how climate can affect human history. %0 journal article %@ 2190-4979 %A Vrese, P.de, Stacke, T., Hagemann, S. %D 2018 %J Earth System Dynamics %N 2 %P 393-412 %R doi:10.5194/esd-9-393-2018 %T Exploring the biogeophysical limits of global food production under different climate change scenarios %U https://doi.org/10.5194/esd-9-393-2018 2 %X An adapted Earth system model is used to investigate the limitations that future climate and water availability impose on the potential expansion and productivity of croplands. The model maximizes the cropland area under prevailing climate conditions and accounts for an optimized, sustainable irrigation practice, thus allowing us to consider the two-way feedback between climate and agriculture. For three greenhouse gas concentration scenarios (RCP2.6, RCP4.5, RCP8.5), we show that the total cropland area could be extended substantially throughout the 21st century, especially in South America and sub-Saharan Africa, where the rising water demand resulting from increasing temperatures can largely be met by increasing precipitation and irrigation rates. When accounting for the CO2 fertilization effect, only a few agricultural areas have to be abandoned owing to declines in productivity, while increasing temperatures allow for the expansion of croplands even into high northern latitudes. Without the CO2 fertilization effect there is no increase in the overall cropland fraction during the second half of the century but areal losses in increasingly water-stressed regions can be compensated for by an expansion in regions that were previously too cold. However, global yields are more sensitive and, without the benefits of CO2 fertilization, they may decrease when greenhouse gas concentrations exceed the RCP4.5 scenario. For certain regions the situation is even more concerning and guaranteeing food security in dry areas in Northern Africa, the Middle East and South Asia will become increasingly difficult, even for the idealized scenarios investigated in this study. %0 journal article %@ 2575-8950 %A Kappenberg, J., Berendt, M., Ohle, N., Riethmueller, R., Schuster, D., Strotmann, T. %D 2018 %J Civil Engineering Research Journal (CERJ) %N 4 %P 555643 %R doi:10.19080/CERJ.2018.04.555643 %T Variation of Hydrodynamics and Water Constituents in the Mouth of the Elbe Estuary, Germany %U https://doi.org/10.19080/CERJ.2018.04.555643 4 %X Results of long-term measurements of CTD, current velocity, turbidity, and dissolved oxygen from three stations in the mouth of the Elbe Estuary in northern Germany are presented for the period of 2012 and 2013. The focus is on a station named HPA-Elbe 1, which was part of the COSYNA coastal observing system for northern and arctic seas, but data from two neighbouring stations are also presented for comparison and to bridge gaps in the time-series of HPA-Elbe 1. The variations of the variables exhibit distinct tidal patterns related to the longitudinal estuarine gradients of the water constituents and local sediment dynamics. On longer time-scales, spring-neap variability is observed, most prominently in the hydrodynamics. On the seasonal scale, the water temperature influences the degradation processes, which deplete the dissolved oxygen on the one hand and increase the oxygen contents by biological respiration on the other hand. Freshwater events from the catchment play an important role for sediment dynamics and mixing of riverine and coastal waters in the brackish water reach of the estuary. The periods of the deployment of the stations comprise the severest river flood observed so far in the Elbe in June 2013. The effects of the flood at the stations and along the estuary consist of a rapid flushing of the mixing zone and the turbidity maximum to the outer estuary and the transition to freshwater conditions from Hamburg to the mouth at Cuxhaven. The impact of the river flood at the stations is more pronounced in changes in salinity than in turbidity. The restoration of estuarine salinity and turbidity values comparable to those before the river flood took several months. %0 journal article %@ 0048-9697 %A Mentzafou, A., Wagner, S., Dimitriou, E. %D 2018 %J Science of the Total Environment %P 558-568 %R doi:10.1016/j.scitotenv.2018.04.298 %T Historical trends and the long-term changes of the hydrological cycle components in a Mediterranean river basin %U https://doi.org/10.1016/j.scitotenv.2018.04.298 %X Identifying the historical hydrometeorological trends in a river basin is necessary for understanding the dominant interactions between climate, human activities and local hydromorphological conditions. Estimating the hydrological reference conditions in a river is also crucial for estimating accurately the impacts from human water related activities and design appropriate water management schemes. In this effort, the output of a regional past climate model was used, covering the period from 1660 to 1990, in combination with a dynamic, spatially distributed, hydrologic model to estimate the past and recent trends in the main hydrologic parameters such as overland flow, water storages and evapotranspiration, in a Mediterranean river basin. The simulated past hydrologic conditions (1660–1960) were compared with the current hydrologic regime (1960–1990), to assess the magnitude of human and natural impacts on the identified hydrologic trends. The hydrological components of the recent period of 2008–2016 were also examined in relation to the impact of human activities. The estimated long-term trends of the hydrologic parameters were partially assigned to varying atmospheric forcing due to volcanic activity combined with spontaneous meteorological fluctuations. %0 journal article %@ 0272-7714 %A Valle-Levinson, A., Stanev, E., Badewien, T.H. %D 2018 %J Estuarine, Coastal and Shelf Science %P 270-279 %R doi:10.1016/j.ecss.2018.01.013 %T Tidal and subtidal exchange flows at an inlet of the Wadden Sea %U https://doi.org/10.1016/j.ecss.2018.01.013 %X Observations of underway velocity profiles during complete spring and neap tidal cycles were used to determine whether the spatial structures of tidal and subtidal flows at a tidal inlet in a multiple-inlet embayment are consistent with those observed at single-inlet embayments. Measurements were obtained at the Otzumer Balje, one of the multiple inlets among the East Frisian Islands of the Wadden Sea. The 1.5 km-wide inlet displayed a bathymetric profile consisting of a channel ∼15 m deep flanked by <5 m shoals. Neap tide observations spanned 36 h in the period May 11–12, 2011, while spring tide measurements exceeded 48 h from May 17 to May 19, 2011. Analysis of observations indicate that frictional effects from bathymetry molded tidal flows. Spatial distributions of semidiurnal tidal current amplitude and phase conform to those predicted by an analytical model for a basin with one inlet. Maximum semidiurnal flows appear at the surface in the channel, furthest away from bottom friction effects. Therefore, Otzumer Balje displays tidal hydrodynamics that are independent of the other inlets of the embayment. Subtidal exchange flows are laterally sheared, with residual inflow in the channel combined with outflow over shoals. The spatial distribution of these residual flows follow theoretical expectations of tidally driven flows interacting with bathymetry. Such distribution is similar to the tidal residual circulation at other inlets with only one communication to the ocean, suggesting that at subtidal scales the Otzumer Balje responds to tidal forcing independently of the other inlets. %0 journal article %@ 0094-8276 %A Stanev, E.V., Poulain, P.-M., Grayek, S., Johnson, K.S., Claustre, H., Murray, J.W. %D 2018 %J Geophysical Research Letters %N 2 %P 864-871 %R doi:10.1002/2017GL076206 %T Understanding the Dynamics of the Oxic-Anoxic Interface in the Black Sea %U https://doi.org/10.1002/2017GL076206 2 %X The Black Sea, the largest semienclosed anoxic basin on Earth, can be considered as an excellent natural laboratory for oxic and anoxic biogeochemical processes. The suboxic zone, a thin interface between oxic and anoxic waters, still remains poorly understood because it has been undersampled. This has led to alternative concepts regarding the underlying processes that create it. Existing hypotheses suggest that the interface originates either by isopycnal intrusions that introduce oxygen or the dynamics of manganese redox cycling that are associated with the sinking of particles or chemosynthetic bacteria. Here we reexamine these concepts using high‐resolution oxygen, sulfide, nitrate, and particle concentration profiles obtained with sensors deployed on profiling floats. Our results show an extremely stable structure in density space over the entire basin with the exception of areas near the Bosporus plume and in the southern areas dominated by coastal anticyclones. The absence of large‐scale horizontal intrusive signatures in the open‐sea supports a hypothesis prioritizing the role of biogeochemical processes. %0 journal article %@ 0094-8276 %A Barkhordarian, A., Storch, H.v., Behrangi, A., Loikith, P.C., Mechoso, C.R., Detzer, J. %D 2018 %J Geophysical Research Letters %N 12 %P 6262-6271 %R doi:10.1029/2018GL078041 %T Simultaneous regional detection of land‐use changes and elevated GHG levels: the case of spring precipitation in tropical South America %U https://doi.org/10.1029/2018GL078041 12 %X A decline in dry season precipitation over tropical South America has a large impact on ecosystem health of the region. Results here indicate that the magnitude of negative trends in dry season precipitation in the past decades exceeds the estimated range of trends due to natural variability of the climate system defined in both the pre‐industrial climate and during the 850‐1850 millennium. The observed drying is associate with an increase in vapor pressure deficit. The univariate detection analysis shows that greenhouse gas (GHG) forcing has a systematic influence in negative 30‐year trends of precipitation ending in 1998 and later on. The bivariate attribution analysis demonstrates that forcing by elevated GHG levels and land‐use‐change are attributed as key causes for the observed drying during 1983‐2012 over the southern Amazonia and central Brazil. We further show that the effect of GS signal (Greenhouse gas and Sulfate aerosols) based on RCP4.5 scenario already has a detectable influence in the observed drying. Thus, we suggest that the recently observed “drier dry season” is a feature which will continue and intensify in the course of unfolding anthropogenic climate change. Such change could have profound societal and ecosystem impacts over the region. %0 journal article %@ 1475-4762 %A Petzold, J., Ratter, B.M.W., Holdschlag, A. %D 2018 %J Area %N 1 %P 91-100 %R doi:10.1111/area.12355 %T Competing knowledge systems and adaptability to sea‐level rise in The Bahamas %U https://doi.org/10.1111/area.12355 1 %X In times of climate change and global ecosystem degradation, Small Island Developing States (SIDS) are both showcases and indicators for global social‐ecological dynamics. Resilience is among the most prominent concepts to assess and improve communities’ capacity to adapt to environmental changes, described as adaptability. But how environmental pressures are perceived, and how this perception translates into action and specific behavioural patterns, is regionally different and depends on cultural, historical and cognitive contexts. Within the cultural and regional framing, different knowledge systems can be identified, which affect perception of and behaviour towards environmental concerns. Knowledge systems can be competing, because they are influenced by different and changing cultural identities, experiences, worldviews, norms and (unequal) power relations. How do competing knowledge systems influence adaptability? And how can we learn from them, respectively? By means of qualitative and quantitative empirical research on The Bahamas, we show how different knowledge systems translate into different modes of responding to specific environmental pressures, such as sea‐level rise. The understanding of historicity and temporality, experience and learning processes, and institutional settings, which frame people's knowledge of their environment, is important for understanding potentials for adaptability. %0 journal article %@ 2045-2322 %A Platis, A., Siedersleben, S.K., Bange, J., Lampert, A., Baerfuss, K., Hankers, R., Canadillas, B., Foreman, R., Schulz-Stellenfleth, J., Djath, B., Neumann, T., Emeis, S. %D 2018 %J Scientific Reports %P 2163 %R doi:10.1038/s41598-018-20389-y %T First in situ evidence of wakes in the far field behind offshore wind farms %U https://doi.org/10.1038/s41598-018-20389-y %X More than 12 GW of offshore wind turbines are currently in operation in European waters. To optimise the use of the marine areas, wind farms are typically clustered in units of several hundred turbines. Understanding wakes of wind farms, which is the region of momentum and energy deficit downwind, is important for optimising the wind farm layouts and operation to minimize costs. While in most weather situations (unstable atmospheric stratification), the wakes of wind turbines are only a local effect within the wind farm, satellite imagery reveals wind-farm wakes to be several tens of kilometres in length under certain conditions (stable atmospheric stratification), which is also predicted by numerical models. The first direct in situ measurements of the existence and shape of large wind farm wakes by a specially equipped research aircraft in 2016 and 2017 confirm wake lengths of more than tens of kilometres under stable atmospheric conditions, with maximum wind speed deficits of 40%, and enhanced turbulence. These measurements were the first step in a large research project to describe and understand the physics of large offshore wakes using direct measurements, together with the assessment of satellite imagery and models. %0 journal article %@ 1475-4762 %A Doering, M., Ratter, B.M.W. %D 2018 %J Area %N 2 %P 169-176 %R doi:10.1111/area.12382 %T Coastal landscapes: The relevance of researching coastscapes for managing coastal change in North Frisia %U https://doi.org/10.1111/area.12382 2 %X Studies on the socio‐cultural dimensions of perceiving and framing landscapes represent a well‐established interdisciplinary field of research cutting across the disciplines of geography, anthropology and sociology. Most studies to date converge in the fact that they theoretically and methodologically revolve around textual and symbolic landscape approaches to investigate underlying social representations and practices permeating the physical land: littoral landscapes – to be understood as a subcategory of landscapes – have however received limited attention to date. The paper takes this gap as a starting point to conceptually explore the intersections of different approaches in landscape research for analysing the manifold bonds coastal inhabitants form with their coastal landscapes. The study draws on semi‐structured interviews conducted with coastal inhabitants in the district of North Frisia (Germany). Interviews were analysed following Grounded Theory and refined by a linguistic indepth investigation to reveal different representations of the North Frisian coastscape nestling in coastal dweller's discourse. The analysis brought about aesthetic, genealogical and other interpretative repertoires saturated with a variety of linguistic characteristics developing locally bound patterns of coastscape attachment. The aim of the paper is twofold: first, it consists of an attempt to analytically combine research undertaken in the area of landscape with research on coastal landscapes to uncover the multifarious relations coastal inhabitants form with their livelihoods. Second, it reflects on the epistemological challenges of research on various coastal landscapes for managing coastal change in terms of a “coast‐multiple”. %0 journal article %@ 0272-7714 %A Holzwarth, I., Wirtz, K. %D 2018 %J Estuarine, Coastal and Shelf Science %P 45-61 %R doi:10.1016/j.ecss.2018.01.020 %T Anthropogenic impacts on estuarine oxygen dynamics: A model based evaluation %U https://doi.org/10.1016/j.ecss.2018.01.020 %X Thus, our study demonstrates the relevance of bathymetric factors during the assessment of human interference on DO dynamics and biogeochemical processes in estuaries. %0 journal article %@ 1680-7316 %A Slemr, F., Weigelt, A., Ebinghaus, R., Bieser, J., Brenninkmeijer, C., Rauthe-Schöch, A., Hermann, M., Martinsson, B., van Velthoven, P., Bönisch, H., Neumaier, M., Zahn, A., Ziereis, H. %D 2018 %J Atmospheric Chemistry and Physics %N 16 %P 12329-12343 %R doi:10.5194/acp-18-12329-2018 %T Mercury distribution in the upper troposphere and lowermost stratosphere according to measurements by the IAGOS-CARIBIC observatory: 2014–2016 %U https://doi.org/10.5194/acp-18-12329-2018 16 %X Increased upper tropospheric total mercury (TM) concentrations due to large scale biomass burning were observed in the upper troposphere (UT) at the equator and southern latitudes during the flights to Latin America and South Africa in boreal autumn (SON) and boreal winter (DJF). TM concentrations in the lowermost stratosphere (LMS) decrease with altitude above the thermal tropopause but the gradient is less steep than reported before. Seasonal variation of the vertical TM distribution in the UT and LMS is similar to that of other trace gases with surface sources and stratospheric sinks. Speciation experiments suggest comparable TM and gaseous elementary mercury (GEM) concentrations at and below the tropopause leaving little space for Hg2+ (TM − GEM) being the dominating component of TM here. In the stratosphere significant GEM concentrations were found to exist up to 4 km altitude above the thermal tropopause. Correlations with N2O as a reference tracer suggest stratospheric lifetimes of 72±37 and 74±27 years for TM and GEM, respectively, comparable to the stratospheric lifetime of COS. This coincidence, combined with pieces of evidence from us and other researchers, corroborates the hypothesis that Hg2+ formed by oxidation in the stratosphere attaches to sulfate particles formed mainly by oxidation of COS and is removed with them from the stratosphere by air mass exchange, gravitational sedimentation and cloud scavenging processes. %0 journal article %@ 1680-7316 %A Vivanco, M.G., Theobald, M.R., García-Gómez, H., Luis Garrido, J., Prank, M., Aas, W., Adani, M., Alyuz, U., Andersson, C., Bellasio, R., Bessagnet, B., Bianconi, R., Bieser, J., Brandt, J., Briganti, G., Cappelletti, A., Curci, G., Christensen, J.H., Colette, A., Couvidat, F., Cuvelier, C., D'Isidoro, M., Flemming, J., Fraser, A., Geels, C., Hansen, K.M., Hogrefe, C., Im, U., Jorba, O., Kitwiroon, N., Manders, A., Mircea, M., Otero, N., Pay, M.-T., Pozzoli, L., Solazzo, E., Tsyro, S., Unal, A., Wind, P., Galmarini, S. %D 2018 %J Atmospheric Chemistry and Physics %N 14 %P 10199-10218 %R doi:10.5194/acp-18-10199-2018 %T Modeled deposition of nitrogen and sulfur in Europe estimated by 14 air quality model systems: evaluation, effects of changes in emissions and implications for habitat protection %U https://doi.org/10.5194/acp-18-10199-2018 14 %X Moreover, simulations with reduced emissions in selected source areas indicated a fairly linear relationship between reductions in emissions and changes in the deposition rates of N and S. An approximate 20 % reduction in N and S deposition in Europe is found when emissions at a global scale are reduced by the same amount. European emissions are by far the main contributor to deposition in Europe, whereas the reduction in deposition due to a decrease in emissions in North America is very small and confined to the western part of the domain. Reductions in European emissions led to substantial decreases in the protected habitat areas with critical load exceedances (halving the exceeded area for certain habitats), whereas no change was found, on average, when reducing North American emissions in terms of average values per habitat. %0 journal article %@ 1680-7316 %A Im, U., Christensen, J.H., Geels, C., Hansen, K.M., Brandt, J., Solazzo, E., Alyuz, U., Balzarini, A., Baro, R., Bellasio, R., Bianconi, R., Bieser, J., Colette, A., Curci, G., Farrow, A., Flemming, J., Fraser, A., Jimenez-Guerrero, P., Kitwiroon, N., Liu, P., Nopmongcol, U., Palacios-Peña, L., Pirovano, G., Pozzoli, L., Prank, M., Rose, R., Sokhi, R., Tuccella, P., Unal, A., Vivanco, M.G., Yarwood, G., Hogrefe, C., Galmarini, S. %D 2018 %J Atmospheric Chemistry and Physics %N 12 %P 8929-8952 %R doi:10.5194/acp-18-8929-2018 %T Influence of anthropogenic emissions and boundary conditions on multi-model simulations of major air pollutants over Europe and North America in the framework of AQMEII3 %U https://doi.org/10.5194/acp-18-8929-2018 12 %X In addition, values of the Response to Extra-Regional Emission Reductions (RERER) metric have been calculated in order to quantify the differences in the strengths of non-local source contributions to different species among the different models. We found large RERER values for O3 (∼ 0.8) over both Europe and North America, indicating a large contribution from non-local sources, while for other pollutants including particles, low RERER values reflect a predominant control by local sources. A distinct seasonal variation in the local vs. non-local contributions has been found for both O3 and PM2.5, particularly reflecting the springtime long-range transport to both continents. %0 journal article %@ 0276-0460 %A Kudrass, H., Machalett, B., Palamenghi, L., Meyer, I., Zhang, W. %D 2018 %J Geo-Marine Letters %P 481-496 %R doi:10.1007/s00367-018-0550-x %T Sediment transport by tropical cyclones recorded in a submarine canyon off Bangladesh %U https://doi.org/10.1007/s00367-018-0550-x %X Frequent cyclones originating in the Bay of Bengal landfall on the delta coast of the Ganges and Brahmaputra rivers. The cyclones are well recorded in the sediments of a canyon that is deeply incised into the shelf offshore Bangladesh. The large mud supply by the two rivers forms temporary deposits on the innermost shelf, where they are mobilized by waves and currents during the passage of cyclones. The resulting, highly concentrated fine sand-silt-clay suspension is moved by wind-induced currents and eventually plunges into the shelf canyon. These gravity flows are deposited as graded beds on the broad canyon floor. In a 362-cm-long section of a dated sediment core covering the period from 2006 to 1985, nearly all 59 graded beds can be correlated with 42 cyclones observed in that period. The threefold decrease in the sedimentation rate of the last decade compared to the period from 1994 to 1954 is due to the decreased number and power of cyclones. Compared to the sediment transfer by cyclones, the input by local sediment slumps, tidal currents, and monsoonal floods is small. Thus, cyclones dominate the mobilization and distribution of sediment on the Bangladesh shelf. This sediment dispersal mechanism is probably also typical for other shelf areas crossed by tropical cyclones. %0 journal article %@ 1680-7316 %A Im, U., Brandt, J., Geels, C., Hansen, K.M., Christensen, J.H., Andersen, M.S., Solazzo, E., Kioutsioukis, I., Alyuz, U., Balzarini, A., Baro, R., Bellasio, R., Bianconi, R., Bieser, J., Colette, A., Curci, G., Farrow, A., Flemming, J., Fraser, A., Jimenez-Guerrero, P., Kitwiroon, N., Liang, C.-K., Nopmongcol, U., Pirovano, G., Pozzoli, L., Prank, M., Rose, R., Sokhi, R., Tuccella, P., Unal, A., Garcia Vivanco, M., West, J., Yarwood, G., Hogrefe, C., Galmarini, S. %D 2018 %J Atmospheric Chemistry and Physics %N 8 %P 5967-5989 %R doi:10.5194/acp-18-5967-2018 %T Assessment and economic valuation of air pollution impacts on human health over Europe and the United States as calculated by a multi-model ensemble in the framework of AQMEII3 %U https://doi.org/10.5194/acp-18-5967-2018 8 %X A total of 54 000 and 27 500 premature deaths can be avoided by a 20 % reduction of global anthropogenic emissions in Europe and the US, respectively. A 20 % reduction of North American anthropogenic emissions avoids a total of  ∼  1000 premature deaths in Europe and 25 000 total premature deaths in the US. A 20 % decrease of anthropogenic emissions within the European source region avoids a total of 47 000 premature deaths in Europe. Reducing the east Asian anthropogenic emissions by 20 % avoids  ∼  2000 total premature deaths in the US. These results show that the domestic anthropogenic emissions make the largest impacts on premature deaths on a continental scale, while foreign sources make a minor contribution to adverse impacts of air pollution. %0 journal article %@ 2169-897X %A Li, D., Storch, H.v., Yin, B., Xu, Z., Qi, J., Wei, W., Guo, D. %D 2018 %J Journal of Geophysical Research : Atmospheres %N 10 %P 5240-5260 %R doi:10.1029/2017JD027949 %T Low-Level Jets Over the Bohai Sea and Yellow Sea: Climatology, Variability, and the Relationship with Regional Atmospheric Circulations %U https://doi.org/10.1029/2017JD027949 10 %X The present study reveals climate features of low‐level jets (LLJs) over the Bohai Sea and Yellow Sea (BYS) based on a 35‐year (1979–2013) high‐resolution (7 km) atmospheric hindcast. The regional climate model COSMO‐CLM driven by the ERA‐Interim reanalysis data set was used to obtain the hindcast. Through comparison with observations, the hindcast was proved to robustly reproduce the climatology, the diurnal cycle, the variability of wind profiles, and specific LLJ cases. LLJs over the BYS feature a strong diurnal cycle, intra‐annual, and interannual variability but weak decadal variability. LLJs are more frequent in April, May, and June (LLJ season) and less frequent in winter over the Bohai Sea and western coastal areas of the Yellow Sea, which is due to the intra‐annual variations of large‐scale circulation and local land‐sea thermal contrast. In the LLJ season, the heights of jet cores are generally lower than 500 m above sea level. The maximum wind speed of LLJs is mostly in the range of 10–16 m/s, and prevailing wind directions are southerly and southwesterly. The LLJs are of the nocturnal type, with the highest occurrence frequency at approximately 2300 local time. Furthermore, a low‐frequency link between anomalies of LLJ occurrence and regional large‐scale barotropic circulation was identified using canonical correlation analysis and associated correlation patterns. Pressure systems over the East Asia‐northwest Pacific region are significantly correlated with the variations of LLJ occurrence over the BYS in terms of the intra‐annual and interannual variability. %0 journal article %@ 0278-4343 %A Chen, W., de Swart, H. %D 2018 %J Continental Shelf Research %N 1 %P 1-13 %R doi:10.1016/j.csr.2018.07.011 %T Estuarine residual flow induced by eddy viscosity-shear covariance: Dependence on axial bottom slope, tidal intensity and constituents %U https://doi.org/10.1016/j.csr.2018.07.011 1 %X Residual flow generated by Eddy viscosity-Shear Covariance (ESCO) in a narrow estuary is investigated with a numerical model. New aspects concern the dependence of the spatial structure of ESCO flow on (1) longitudinal depth variation for fixed semi-diurnal tidal forcing, (2) varying amplitude of the semi-diurnal tidal forcing, and (3) mixed tidal forcing for fixed stratification at the mouth. Regarding (1) and (2), it appears that ESCO flow merely involves the components due to the semi-diurnal tide and quarter-diurnal tide . For a periodically stratified estuary, is stronger than in the middle reach, and weaker in the other reaches, while both show a two-layer structure with seaward flow near the surface. For weak stratification, has a three-layer structure with seaward flow in the middle layer, while has a two-layer structure and contributes significantly to the total residual flow in the upper and lower reach. For a highly stratified estuary, dominates the ESCO flow (being weak compared to the total residual flow), and it has a reversed two-layer structure (seaward flow near the bottom). Regarding (3), if diurnal and semi-diurnal tides are of similar order, the ESCO flow due to diurnal tides dominates and it has a two-layer structure. If diurnal tides prevail, the ESCO flow induced by the long-periodic tide (due to joint action of two diurnal tides) is the main contributor to the total residual flow in the upper and lower reach of the estuary. %0 journal article %@ 2190-4979 %A Robinson, D., Di Vittorio, A., Alexander, P., Arneth, A., Barton, M., Brown, D., Kettner, A., Lemmen, C., O'Neill, B., Janssen, M., Pugh, T., Rabin, S., Rounsevell, M., Syvitski, J., Ullah, I., Verburg, P. %D 2018 %J Earth System Dynamics %N 2 %P 895-914 %R doi:10.5194/esd-9-895-2018 %T Modelling feedbacks between human and natural processes in the land system %U https://doi.org/10.5194/esd-9-895-2018 2 %X The unprecedented use of Earth's resources by humans, in combination with increasing natural variability in natural processes over the past century, is affecting the evolution of the Earth system. To better understand natural processes and their potential future trajectories requires improved integration with and quantification of human processes. Similarly, to mitigate risk and facilitate socio-economic development requires a better understanding of how the natural system (e.g. climate variability and change, extreme weather events, and processes affecting soil fertility) affects human processes. Our understanding of these interactions and feedback between human and natural systems has been formalized through a variety of modelling approaches. However, a common conceptual framework or set of guidelines to model human–natural-system feedbacks is lacking. The presented research lays out a conceptual framework that includes representing model coupling configuration in combination with the frequency of interaction and coordination of communication between coupled models. Four different approaches used to couple representations of the human and natural system are presented in relation to this framework, which vary in the processes represented and in the scale of their application. From the development and experience associated with the four models of coupled human–natural systems, the following eight lessons were identified that if taken into account by future coupled human–natural-systems model developments may increase their success: (1) leverage the power of sensitivity analysis with models, (2) remember modelling is an iterative process, (3) create a common language, (4) make code open-access, (5) ensure consistency, (6) reconcile spatio-temporal mismatch, (7) construct homogeneous units, and (8) incorporating feedback increases non-linearity and variability. Following a discussion of feedbacks, a way forward to expedite model coupling and increase the longevity and interoperability of models is given, which suggests the use of a wrapper container software, a standardized applications programming interface (API), the incorporation of standard names, the mitigation of sunk costs by creating interfaces to multiple coupling frameworks, and the adoption of reproducible workflow environments to wire the pieces together. %0 journal article %@ 1476-945X %A Bengfort, M., Siekmann, I., Malchow, H. %D 2018 %J Ecological Complexity %P 134-138 %R doi:10.1016/j.ecocom.2017.09.001 %T Invasive competition with Fokker-Planck diffusion and noise %U https://doi.org/10.1016/j.ecocom.2017.09.001 %X Species competition in a fluctuating environment is often modelled with stochastic reaction-diffusion equations. In most cases the movement of individuals is described as Fickian diffusion. However, in heterogeneous environments this is not the first choice. Recently, it has been shown that Fokker-Planck diffusion describes the movement of species in a more realistic way. Fickian diffusion always leads to spatially uniform stationary distributions whereas the Fokker-Planck diffusion generates nonuniform solutions according to the heterogeneity of the environment and the corresponding spatial variation of diffusion. Species accumulate in regions of low diffusivity and tend to lower their densities in areas of high diffusivity. In the present paper, the impact of Fokker-Planck diffusion is studied with particular consideration of changing spatio-temporal population patterns during the competitive invasion of a spatially heterogeneous, populated habitat. The standard Lotka-Volterra competition model is applied to describe the resident-invader interaction. The resident is assumed to be adapted to the heterogeneous living conditions, i.e., its motion is modelled as space-dependent Fokker-Planck diffusion. The invader's diffusion is taken as neutral Fickian. Furthermore, it is shown that multiplicative environmental noise can either foster or hinder the invasion. %0 journal article %@ 1680-7316 %A Liu, P., Hogrefe, C., Im, U., Christensen, J., Bieser, J., Nopmongcol, U., Yarwood, G., Mathur, R., Roselle, S., Spero, T. %D 2018 %J Atmospheric Chemistry and Physics %N 23 %P 17157-17175 %R doi:10.5194/acp-18-17157-2018 %T Attributing differences in the fate of lateral boundary ozone in AQMEII3 models to physical process representations %U https://doi.org/10.5194/acp-18-17157-2018 23 %X COSMO-CLM∕CMAQ and WRF∕CMAQ show similar performance in inert tracers both at the surface and aloft through most seasons, which suggests similarity between the two models at process level. The largest difference is found in summer. Sub-grid cloud mixing plays a primary role in their differences in inert tracers over the southeastern US and the oceans in summer. Our analysis of the vertical profiles of inert tracers also suggests that the model differences in dry deposition over certain regions are offset by the model differences in vertical turbulent mixing, leading to small differences in inert tracers at the surface in these regions. %0 journal article %@ 0048-9697 %A Kerimoglu, O., Große, F., Kreus, M., van Beusekom, J. %D 2018 %J Science of the Total Environment %P 1311-1323 %R doi:10.1016/j.scitotenv.2018.05.215 %T A model-based projection of historical state of a coastal ecosystem: Relevance of phytoplankton stoichiometry %U https://doi.org/10.1016/j.scitotenv.2018.05.215 %X We employed a coupled physical-biogeochemical modelling framework for the reconstruction of the historic (H), pre-industrial state of a coastal system, the German Bight (southeastern North Sea), and we investigated its differences with the recent, control (C) state of the system. According to our findings: i) average winter concentrations of dissolved inorganic nitrogen and phosphorus (DIN and DIP) concentrations at the surface are ∼70–90% and ∼50–70% lower in the H state than in the C state within the nearshore waters, and differences gradually diminish towards off-shore waters; ii) differences in average growing season chlorophyll a (Chl) concentrations at the surface between the two states are mostly less than 50%; iii) in the off-shore areas, Chl concentrations in the deeper layers are affected less than in the surface layers; iv) reductions in phytoplankton carbon (C) biomass under the H state are weaker than those in Chl, due to the generally lower Chl:C ratios; v) in some areas the differences in growth rates between the two states are negligible, due to the compensation by lower light limitation under the H state, which in turn explains the lower Chl:C ratios; vi) zooplankton biomass, and hence the grazing pressure on phytoplankton is lower under the H state. This trophic decoupling is caused by the low nutritional quality (i.e., low N:C and P:C) of phytoplankton. These results call for increased attention to the relevance of the acclimation capacity and stoichiometric flexibility of phytoplankton for the prediction of their response to environmental change. %0 journal article %@ 0029-8018 %A Björkqvist, J., Lukas, I., Alari, V., Vledder, G., Hulst, S., Pettersson, H., Behrens, A., Männik, A. %D 2018 %J Ocean Engineering %P 57-71 %R doi:10.1016/j.oceaneng.2018.01.048 %T Comparing a 41-year model hindcast with decades of wave measurements from the Baltic Sea %U https://doi.org/10.1016/j.oceaneng.2018.01.048 %X We present ice-free and ice-included statistics for the Baltic Sea using a wave hindcast validated against data from 13 wave measurement sites. In the hindcast 84% of wave events with a significant wave height over 7 m occurred between November and January. The effect of the ice cover is largest in the Bay of Bothnia, where the mean significant wave height is reduced by 30% when the ice time is included in the statistics. The difference between these two statistics are less than 0.05 m below a latitude of 59.5°. The seasonal ice cover also causes measurement gaps by forcing an early recovery of the instruments. Including the time not captured by the wave buoy can affect the estimates for the significant wave height by roughly 20%. The impact below the 99th percentiles are still under 5%. The significant wave height is modelled accurately even close to the shore, but the highest peak periods are underestimated in a narrow bay. Sensitivity test show that this underestimation is most likely caused by an excessive refraction towards the shore. Reconsidering the role of the spatial resolution and the physical processes affecting the low-frequency waves is suggested as a possible solution. %0 journal article %@ 1812-0784 %A Tchilibou, M., Gourdeau, L., Morrow, R., Serazin, G., Djath, B., Lyard, F. %D 2018 %J Ocean Science %N 5 %P 1283-1301 %R doi:10.5194/os-14-1283-2018 %T Spectral signatures of the tropical Pacific dynamics from model and altimetry: a focus on the meso-/submesoscale range %U https://doi.org/10.5194/os-14-1283-2018 5 %X The processes that contribute to the flat sea surface height (SSH) wavenumber spectral slopes observed in the tropics by satellite altimetry are examined in the tropical Pacific. The tropical dynamics are first investigated with a 1∕12∘ global model. The equatorial region from 10∘ N to 10∘ S is dominated by tropical instability waves with a peak of energy at 1000 km wavelength, strong anisotropy, and a cascade of energy from 600 km down to smaller scales. The off-equatorial regions from 10 to 20∘ latitude are characterized by a narrower mesoscale range, typical of midlatitudes. In the tropics, the spectral taper window and segment lengths need to be adjusted to include these larger energetic scales. The equatorial and off-equatorial regions of the 1∕12∘ model have surface kinetic energy spectra consistent with quasi-geostrophic turbulence. The balanced component of the dynamics slightly flattens the EKE spectra, but modeled SSH wavenumber spectra maintain a steep slope that does not match the observed altimetric spectra. A second analysis is based on 1∕36∘ high-frequency regional simulations in the western tropical Pacific, with and without explicit tides, where we find a strong signature of internal waves and internal tides that act to increase the smaller-scale SSH spectral energy power and flatten the SSH wavenumber spectra, in agreement with the altimetric spectra. The coherent M2 baroclinic tide is the dominant signal at ∼140 km wavelength. At short scales, wavenumber SSH spectra are dominated by incoherent internal tides and internal waves which extend up to 200 km in wavelength. These incoherent internal waves impact space scales observed by today's along-track altimetric SSH, and also on the future Surface Water Ocean Topography (SWOT) mission 2-D swath observations, raising the question of altimetric observability of the shorter mesoscale structures in the tropics. %0 journal article %@ 0941-2948 %A Siedersleben, S.K., Platis, A., Lundquist, J.K., Lampert, A., Baerfuss, K., Canadillas, B., Djath, B., Schulz-Stellenfleth, J., Bange, J., Neumann, T., Emeis, S. %D 2018 %J Meteorologische Zeitschrift %N 5 %P 401-415 %R doi:10.1127/metz/2018/0900 %T Evaluation of a Wind Farm Parametrization for Mesoscale Atmospheric Flow Models with Aircraft Measurements %U https://doi.org/10.1127/metz/2018/0900 5 %X Large offshore wind farms are usually clustered around transmission grids to minimize the expense of transmission and due to space military zones, pipelines and constrains due to other uses such as nature preserves. However, this close proximity can undermine power production in downwind wind farms due to wakes from upwind wind farms. Therefore, the wind energy industry has great interest in determining the spatial dimensions of offshore wind farm wakes to assess the economical potential of planned wind farms. In this work we use wake measurements conducted by a research aircraft to evaluate the performance of a wind farm parameterization (WFP) in a mesoscale model during stably-stratified atmospheric conditions, in which the wake is expected to be the strongest. The observations were conducted on the 10 September 2016 within the project WIPAFF (Wind PArk Far Field) at the North Sea. The observations allow evaluation of both the horizontal and the vertical dimensions of the wake. The model simulates the length and most of the time the spatial dimensions of the wake. Further, we show that the largest potential for improving the performance of the WFP is rooted in an improvement of the background flow. This is due to the fact that the mesoscale model has problems representing the atmospheric boundary layer in the transition between land to open sea. %0 journal article %@ 2045-2322 %A Mohammadi-Aragh, M., Goessling, H., Losch, M., Hutter, N., Jung, T. %D 2018 %J Scientific Reports %P 6514 %R doi:10.1038/s41598-018-24660-0 %T Predictability of Arctic sea ice on weather time scales %U https://doi.org/10.1038/s41598-018-24660-0 %X The field of Arctic sea ice prediction on “weather time scales” is still in its infancy with little existing understanding of the limits of predictability. This is especially true for sea ice deformation along so-called Linear Kinematic Features (LKFs) including leads that are relevant for marine operations. Here the potential predictability of the sea ice pack in the wintertime Arctic up to ten days ahead is determined, exploiting the fact that sea ice-ocean models start to show skill at representing sea ice deformation at high spatial resolutions. Results are based on ensemble simulations with a high-resolution sea ice-ocean model driven by atmospheric ensemble forecasts. The predictability of LKFs as measured by different metrics drops quickly, with predictability being almost completely lost after 4–8 days. In contrast, quantities such as sea ice concentration or the location of the ice edge retain high levels of predictability throughout the full 10-day forecast period. It is argued that the rapid error growth for LKFs is mainly due to the chaotic behaviour of the atmosphere associated with the low predictability of near surface wind divergence and vorticity; initial condition uncertainty for ice thickness is found to be of minor importance as long as LKFs are initialized at the right locations. %0 journal article %@ 2296-7745 %A Meier, H., Edman, M., Eilola, K., Placke, M., Neumann, T., Andersson, H., Brunnabend, S., Dieterich, C., Frauen, C., Friedland, R., Gröger, M., Gustafsson, B., Gustafsson, E., Isaev, A., Kniebusch, M., Kuznetsov, I., Müller-Karulis, B., Omstedt, A., Ryabchenko, V., Saraiva, S., Savchuk, O. %D 2018 %J Frontiers in Marine Science %P 440 %R doi:10.3389/fmars.2018.00440 %T Assessment of Eutrophication Abatement Scenarios for the Baltic Sea by Multi-Model Ensemble Simulations %U https://doi.org/10.3389/fmars.2018.00440 %X To assess the impact of the implementation of the Baltic Sea Action Plan (BSAP) on the future environmental status of the Baltic Sea, available uncoordinated multi-model ensemble simulations for the Baltic Sea region for the twenty-first century were analyzed. The scenario simulations were driven by regionalized global general circulation model (GCM) data using several regional climate system models and forced by various future greenhouse gas emission and air- and river-borne nutrient load scenarios following either reference conditions or the BSAP. To estimate uncertainties in projections, the largest ever multi-model ensemble for the Baltic Sea comprising 58 transient simulations for the twenty-first century was assessed. Data from already existing simulations from different projects including regionalized GCM simulations of the third and fourth assessment reports of the Intergovernmental Panel on Climate Change based on the corresponding Coupled Model Intercomparison Projects, CMIP3 and CMIP5, were collected. Various strategies to weigh the ensemble members were tested and the results for ensemble mean changes between future and present climates are shown to be robust with respect to the chosen metric. Although (1) the model simulations during the historical period are of different quality and (2) the assumptions on nutrient load levels during present and future periods differ between models considerably, the ensemble mean changes in biogeochemical variables in the Baltic proper with respect to nutrient load reductions are similar between the entire ensemble and a subset consisting only of the most reliable simulations. Despite the large spread in projections, the implementation of the BSAP will lead to a significant improvement of the environmental status of the Baltic Sea according to both weighted and unweighted ensembles. The results emphasize the need for investigating ensembles with many members and rigorous assessments of models' performance. %0 journal article %@ 0025-326X %A Gutow, L., Ricker, M., Holstein, J., Dannheim, J., Stanev, E., Wolff, J. %D 2018 %J Marine Pollution Bulletin %N Part A %P 763-772 %R doi:10.1016/j.marpolbul.2018.05.003 %T Distribution and trajectories of floating and benthic marine macrolitter in the south-eastern North Sea %U https://doi.org/10.1016/j.marpolbul.2018.05.003 Part A %X In coastal waters the identification of sources, trajectories and deposition sites of marine litter is often hampered by the complex oceanography of shallow shelf seas. We conducted a multi-annual survey on litter at the sea surface and on the seafloor in the south-eastern North Sea. Bottom trawling was identified as a major source of marine litter. Oceanographic modelling revealed that the distribution of floating litter in the North Sea is largely determined by the site of origin of floating objects whereas the trajectories are strongly influenced by wind drag. Methods adopted from species distribution modelling indicated that resuspension of benthic litter and near-bottom transport processes strongly influence the distribution of litter on the seafloor. Major sink regions for floating marine litter were identified at the west coast of Denmark and in the Skagerrak. Our results may support the development of strategies to reduce the pollution of the North Sea. %0 journal article %@ 1812-0784 %A Bonaduce, A., Benkiran, M., Remy, E., Le Traon, P., Garric, G. %D 2018 %J Ocean Science %N 6 %P 1405-1421 %R doi:10.5194/os-14-1405-2018 %T Contribution of future wide-swath altimetry missions to ocean analysis and forecasting %U https://doi.org/10.5194/os-14-1405-2018 6 %X The impact of forthcoming wide-swath altimetry missions on the ocean analysis and forecasting system was investigated by means of OSSEs (observing system simulation experiments). These experiments were performed with a regional data assimilation system, implemented in the Iberian–Biscay–Ireland (IBI) region, at 1∕12∘ resolution using simulated observations derived from a fully eddy-resolving free simulation at 1∕36∘ resolution over the same region. The objective of the experiments was to assess the ability of different satellite constellations to constrain the ocean analyses and forecasts, considering both along-track altimeters and future wide-swath missions; consequently, the capability of the data assimilation techniques used in the Mercator Ocean operational system to effectively combine the different kinds of measurements was also investigated. These assessments were carried out as part of a European Space Agency (ESA) study on the potential role of wide-swath altimetry in future versions of the European Union Copernicus programme. The impact of future wide-swath altimetry data is evident for investigating the reliability of sea level values in OSSEs. The most significant results were obtained when looking at the sensitivity of the system to wide-swath instrumental error: considering a constellation of three nadir and two “accurate” (small instrumental error) wide-swath altimeters, the error in ocean analysis was reduced by up to 50 % compared to conventional altimeters. Investigating the impact of the repetitivity of the future measurements, the results showed that two wide-swath missions had a major impact on sea-level forecasting – increasing the accuracy over the entire time window of the 5-day forecasts – compared with a single wide-swath instrument. A spectral analysis underlined that the contributions of wide-swath altimetry data observed in ocean analyses and forecast statistics were mainly due to the more accurate resolution, compared with along-track data, of ocean variability at spatial scales smaller than 100 km. Considering the ocean currents, the results confirmed that the information provided by wide-swath measurements at the surface is propagated down the water column and has a considerable impact (30 %) on ocean currents (up to a depth of 300 m), compared with the present constellation of altimeters. The ocean analysis and forecasting systems used here are those currently used by the Copernicus Marine Environment and Monitoring Service (CMEMS) to provide operational services and ocean reanalysis. The results obtained in the OSSEs considering along-track altimeters were consistent with those derived from real data (observing system experiments, OSEs). OSSEs can also be used to assess the potential of new observing systems, and in this study the results showed that future constellations of altimeters will have a major impact on constraining the CMEMS ocean analysis and forecasting systems and their applications. %0 journal article %@ 1616-7341 %A Chen, W., Swart, H. %D 2018 %J Ocean Dynamics %P 309-326 %R doi:10.1007/s10236-018-1134-z %T Longitudinal variation in lateral trapping of fine sediment in tidal estuaries: observations and a 3D exploratory model %U https://doi.org/10.1007/s10236-018-1134-z %X This study investigates the longitudinal variation of lateral entrapment of suspended sediment, as is observed in some tidal estuaries. In particular, field data from the Yangtze Estuary are analysed, which reveal that in one cross-section, two maxima of suspended sediment concentration (SSC) occur close to the south and north sides, while in a cross-section 2 km down-estuary, only one SSC maximum on the south side is present. This pattern is found during both spring tide and neap tide, which are characterised by different intensities of turbulence. To understand longitudinal variation in lateral trapping of sediment, results of a new three-dimensional exploratory model are analysed. The hydrodynamic part contains residual flow due to fresh water input, density gradients and Coriolis force and due to channel curvature-induced leakage. Moreover, the model includes a spatially varying eddy viscosity that accounts for variation of intensity of turbulence over the spring-neap cycle. By imposing morphodynamic equilibrium, the two-dimensional distribution of sediment in the domain is obtained analytically by a novel procedure. Results reveal that the occurrence of the SSC maxima near the south side of both cross-sections is due to sediment entrapment by lateral density gradients, while the second SSC maximum near the north side of the first cross-section is by sediment transport due to curvature-induced leakage. Coriolis deflection of longitudinal flow also contributes the trapping of sediment near the north side. This mechanism is important in the upper estuary, where the flow due to lateral density gradients is weak. %0 journal article %@ 1680-7316 %A Astitha, M., Kioutsioukis, I., Araya Fisseha, G., Bianconi, R., Bieser, J., Christensen, J.H., Cooper, O.R., Galmarini, S., Hogrefe, C., Im, U., Johnson, B., Liu, P., Nopmongcol, U., Petropavlovskikh, I., Solazzo, E., Tarasick, D.W., Yarwood, G. %D 2018 %J Atmospheric Chemistry and Physics %N 19 %P 13925-13945 %R doi:10.5194/acp-18-13925-2018 %T Seasonal ozone vertical profiles over North America using the AQMEII3 group of air quality models: model inter-comparison and stratospheric intrusions %U https://doi.org/10.5194/acp-18-13925-2018 19 %X This study evaluates simulated vertical ozone profiles produced in the framework of the third phase of the Air Quality Model Evaluation International Initiative (AQMEII3) against ozonesonde observations in North America for the year 2010. Four research groups from the United States (US) and Europe have provided modeled ozone vertical profiles to conduct this analysis. Because some of the modeling systems differ in their meteorological drivers, wind speed and temperature are also included in the analysis. In addition to the seasonal ozone profile evaluation for 2010, we also analyze chemically inert tracers designed to track the influence of lateral boundary conditions on simulated ozone profiles within the modeling domain. Finally, cases of stratospheric ozone intrusions during May–June 2010 are investigated by analyzing ozonesonde measurements and the corresponding model simulations at Intercontinental Chemical Transport Experiment Ozonesonde Network Study (IONS) experiment sites in the western United States. The evaluation of the seasonal ozone profiles reveals that, at a majority of the stations, ozone mixing ratios are underestimated in the 1–6 km range. The seasonal change noted in the errors follows the one seen in the variance of ozone mixing ratios, with the majority of the models exhibiting less variability than the observations. The analysis of chemically inert tracers highlights the importance of lateral boundary conditions up to 250 hPa for the lower-tropospheric ozone mixing ratios (0–2 km). Finally, for the stratospheric intrusions, the models are generally able to reproduce the location and timing of most intrusions but underestimate the magnitude of the maximum mixing ratios in the 2–6 km range and overestimate ozone up to the first kilometer possibly due to marine air influences that are not accurately described by the models. The choice of meteorological driver appears to be a greater predictor of model skill in this altitude range than the choice of air quality model. %0 journal article %@ 1680-7316 %A Galmarini, S., Kioutsioukis, I., Solazzo, E., Alyuz, U., Balzarini, A., Bellasio, R., Benedictow, A.M.K., Bianconi, R., Bieser, J., Brandt, J., Christensen, J.H., Colette, A., Curci, G., Davila, Y., Dong, X., Flemming, J., Francis, X., Fraser, A., Fu, J., Henze, D.K., Hogrefe, C., Im, U., Vivanco, M.G., Jiménez-Guerrero, P., Jonson, J.E., Kitwiroon, N., Manders, A., Mathur, R., Palacios-Peña, L., Pirovano, G., Pozzoli, L., Prank, M., Schultz, M., Sokhi, R.S., Sudo, K., Tuccella, P., Takemura, T., Sekiya, T., Unal, A. %D 2018 %J Atmospheric Chemistry and Physics %N 12 %P 8727-8744 %R doi:10.5194/acp-18-8727-2018 %T Two-scale multi-model ensemble: is a hybrid ensemble of opportunity telling us more? %U https://doi.org/10.5194/acp-18-8727-2018 12 %X In this study we introduce a hybrid ensemble consisting of air quality models operating at both the global and regional scale. The work is motivated by the fact that these different types of models treat specific portions of the atmospheric spectrum with different levels of detail, and it is hypothesized that their combination can generate an ensemble that performs better than mono-scale ensembles. A detailed analysis of the hybrid ensemble is carried out in the attempt to investigate this hypothesis and determine the real benefit it produces compared to ensembles constructed from only global-scale or only regional-scale models. The study utilizes 13 regional and 7 global models participating in the Hemispheric Transport of Air Pollutants phase 2 (HTAP2)–Air Quality Model Evaluation International Initiative phase 3 (AQMEII3) activity and focuses on surface ozone concentrations over Europe for the year 2010. Observations from 405 monitoring rural stations are used for the evaluation of the ensemble performance. The analysis first compares the modelled and measured power spectra of all models and then assesses the properties of the mono-scale ensembles, particularly their level of redundancy, in order to inform the process of constructing the hybrid ensemble. This study has been conducted in the attempt to identify that the improvements obtained by the hybrid ensemble relative to the mono-scale ensembles can be attributed to its hybrid nature. The improvements are visible in a slight increase of the diversity (4 % for the hourly time series, 10 % for the daily maximum time series) and a smaller improvement of the accuracy compared to diversity. Root mean square error (RMSE) improved by 13–16 % compared to G and by 2–3 % compared to R. Probability of detection (POD) and false-alarm rate (FAR) show a remarkable improvement, with a steep increase in the largest POD values and smallest values of FAR across the concentration ranges. The results show that the optimal set is constructed from an equal number of global and regional models at only 15 % of the stations. This implies that for the majority of the cases the regional-scale set of models governs the ensemble. However given the high degree of redundancy that characterizes the regional-scale models, no further improvement could be expected in the ensemble performance by adding yet more regional models to it. Therefore the improvement obtained with the hybrid set can confidently be attributed to the different nature of the global models. The study strongly reaffirms the importance of an in-depth inspection of any ensemble of opportunity in order to extract the maximum amount of information and to have full control over the data used in the construction of the ensemble. %0 journal article %@ 1812-0784 %A Wiese, A., Staneva, J., Schulz-Stellenfleth, J., Behrens, A., Fenoglio-Marc, L., Bidlot, J.-R. %D 2018 %J Ocean Science %N 6 %P 1503-1521 %R doi:10.5194/os-14-1503-2018 %T Synergy of wind wave model simulations and satellite observations during extreme events %U https://doi.org/10.5194/os-14-1503-2018 6 %X In this study, the quality of wave data provided by the new Sentinel-3A satellite is evaluated and the sensitivity of the wave model to wind forcing is tested. We focus on coastal areas, where altimeter data are of lower quality and wave modelling is more complex than for the open ocean. In the first part of the study, the sensitivity of the wave model to wind forcing is evaluated using data with different temporal and spatial resolution, such as ERA-Interim and ERA5 reanalyses, the European Centre for Medium-Range Weather Forecasts (ECMWF) operational analysis and short-range forecasts, German Weather Service (DWD) forecasts and regional atmospheric model simulations (coastDat). Numerical simulations show that the wave model forced using the ERA5 reanalyses and that forced using the ECMWF operational analysis/forecast demonstrate the best capability over the whole study period, as well as during extreme events. To further estimate the variance of the significant wave height of ensemble members for different wind forcings, especially during extreme events, an empirical orthogonal function (EOF) analysis is performed. In the second part of the study, the satellite data of Sentinel-3A, Jason-2 and CryoSat-2 are assessed in comparison with in situ measurements and spectral wave model (WAM) simulations. Intercomparisons between remote sensing and in situ observations demonstrate that the overall quality of the former is good over the North Sea and Baltic Sea throughout the study period, although the significant wave heights estimated based on satellite data tend to be greater than the in situ measurements by 7 to 26 cm. The quality of all satellite data near the coastal area decreases; however, within 10 km off the coast, Sentinel-3A performs better than the other two satellites. Analyses in which data from satellite tracks are separated in terms of onshore and offshore flights have been carried out. No substantial differences are found when comparing the statistics for onshore and offshore flights. Moreover, no substantial differences are found between satellite tracks under various metocean conditions. Furthermore, the satellite data quality does not depend on the wind direction relative to the flight direction. Thus, the quality of the data obtained by the new Sentinel-3A satellite over coastal areas is improved compared to that of older satellites. %0 journal article %@ 1991-959X %A Riddick, T., Brovkin, V., Hagemann, S., Mikolajewicz, U. %D 2018 %J Geoscientific Model Development %N 10 %P 4291-4316 %R doi:10.5194/gmd-11-4291-2018 %T Dynamic hydrological discharge modelling for coupled climate model simulations of the last glacial cycle: the MPI-DynamicHD model version 3.0 %U https://doi.org/10.5194/gmd-11-4291-2018 10 %X The continually evolving large ice sheets present in the Northern Hemisphere during the last glacial cycle caused significant changes to river pathways both through directly blocking rivers and through glacial isostatic adjustment. Studies have shown these river pathway changes had a significant impact on the ocean circulation through changing the pattern of freshwater discharge into the oceans. A coupled Earth system model (ESM) simulation of the last glacial cycle thus requires a hydrological discharge model that uses a set of river pathways that evolve with Earth's changing orography while being able to reproduce the known present-day river network given the present-day orography. Here, we present a method for dynamically modelling river pathways that meets such requirements by applying predefined corrections to an evolving fine-scale orography (accounting for the changing ice sheets and isostatic rebound) each time the river directions are recalculated. The corrected orography thus produced is then used to create a set of fine-scale river pathways and these are then upscaled to a coarser scale on which an existing present-day hydrological discharge model within the JSBACH land surface model simulates the river flow. Tests show that this procedure reproduces the known present-day river network to a sufficient degree of accuracy and is able to simulate plausible paleo-river networks. It has also been shown this procedure can be run successfully multiple times as part of a transient coupled climate model simulation. %0 journal article %@ 2073-4441 %A Lemmen, C. %D 2018 %J Water %N 11 %P 1527 %R doi:10.3390/w10111527 %T North Sea Ecosystem-Scale Model-Based Quantification of Net Primary Productivity Changes by the Benthic Filter Feeder Mytilus edulis %U https://doi.org/10.3390/w10111527 11 %X Blue mussels are among the most abundant bivalves in shallow water along the German coasts. As filter feeders, a major ecosystem service they provide is water filtration and the vertical transfer of suspended organic and attached inorganic material to the sea floor. Laboratory and field studies previously demonstrated that blue mussels can remove large quantities of plankton from the surrounding water. I here perform numerical experiments that investigate the effect of filtration at the scale of an entire coastal sea—the southern North Sea. These experiments were performed with a state-of-the-art bentho-pelagic coupled hydrodynamic and ecosystem model and used a novel reconstruction of the benthic biomass distribution of blue mussels. The filtration effect was assessed as the simulated change in net primary productivity caused by blue mussels. In shallow water, filtration takes out up to half of the entire annual primary productivity; it is negligible in offshore waters. For the entire basin, the filtration effect is 10%. While many ecosystem models have a global parameterization for filter feeders, the coastal gradient in the filtration effect is usually not considered; our research demonstrates the importance of including spatially heterogeneous filtration in coupled bentho-pelagic ecosystem models if we want to better understand the spatial patterns in shallow water coastal systems. %0 journal article %@ 1811-1602 %A Andres, H., Bothe, O., Rehfeld, K., Wagner, S., Weitzel, N., Zorita, E. %D 2018 %J Past Global Changes Magazine %N 2 %P 85 %R doi:10.22498/pages.26.2.85 %T An integrated proxy and simulation data initiative for the Holocene and the last deglaciation %U https://doi.org/10.22498/pages.26.2.85 2 %X Comparing climate proxy and simulation data is fraught with challenges: age and calibration uncertainties in climate proxies, missing or incomplete processes and uncertain boundary conditions for climate models, and differences between gridded and site data are just a few examples. For the climate of the Common Era, multiple initiatives have already addressed these issues (e.g. the PAGES 2k Network regional working groups). On transient timescales beyond the late Holocene, there have been only a few integrated activities. Comparisons on these longer time scales involve large-scale changes in climate states without an equivalent during the Holocene. As such, they require methods that address both the amplitude and timing of background climate changes and account for additional processes. For example, comprehensive Earth System Models need to include changes in ice sheets and related ocean circulation changes during deglaciation. Likewise, proxy data for this period, such as lake or marine sediments, are generally less well replicated than their late Holocene counterparts (e.g. tree rings and historical documents), resulting in more uncertain climate signals (Laepple et al. 2017). %0 journal article %@ 1991-959X %A Krinner, G., Derksen, C., Essery, R., Flanner, M., Hagemann, S., Clark, M., Hall, A., Rott, H., Brutel-Vuilmet, C., Kim, H., Menard, C.B., Mudryk, L., Thackeray, C., Wang, L., Arduini, G., Balsamo, G., Bartlett, P., Boike, J., Boone, A., Cheruy, F., Colin, J., Cuntz, M., Dai, Y., Decharme, B., Derry, J., Ducharne, A., Dutra, E., Fang, X., Fierz, C., Ghattas, J., Gusev, Y., Haverd, V., Kontu, A., Lafaysse, M., Law, R., Lawrence, D., Li, W., Marke, T., Marks, D., Menegoz, M., Nasonova, O., Nitta, T., Niwano, M., Pomeroy, J., Raleigh, M.S., Schaedler, G., Semenov, V., Smirnova, T.G., Stacke, T., Strasser, U., Svenson, S., Turkov, D., Wang, T., Wever, N., Yuan, H., Zhou, W., Zhu, D. %D 2018 %J Geoscientific Model Development %N 12 %P 5027-5049 %R doi:10.5194/gmd-11-5027-2018 %T ESM-SnowMIP: assessing snow models and quantifying snow-related climate feedbacks %U https://doi.org/10.5194/gmd-11-5027-2018 12 %X This paper describes ESM-SnowMIP, an international coordinated modelling effort to evaluate current snow schemes, including snow schemes that are included in Earth system models, in a wide variety of settings against local and global observations. The project aims to identify crucial processes and characteristics that need to be improved in snow models in the context of local- and global-scale modelling. A further objective of ESM-SnowMIP is to better quantify snow-related feedbacks in the Earth system. Although it is not part of the sixth phase of the Coupled Model Intercomparison Project (CMIP6), ESM-SnowMIP is tightly linked to the CMIP6-endorsed Land Surface, Snow and Soil Moisture Model Intercomparison (LS3MIP). %0 journal article %@ 1932-6203 %A Arthun, M., Bogstad, B., Daewel, U., Keenlyside, N.S., Sandoe, A.B., Schrum, C., Ottersen, G. %D 2018 %J PLoS One %N 10 %P e0206319 %R doi:10.1371/journal.pone.0206319 %T Climate based multi-year predictions of the Barents Sea cod stock %U https://doi.org/10.1371/journal.pone.0206319 10 %X Predicting fish stock variations on interannual to decadal time scales is one of the major issues in fisheries science and management. Although the field of marine ecological predictions is still in its infancy, it is understood that a major source of multi-year predictability resides in the ocean. Here we show the first highly skilful long-term predictions of the commercially valuable Barents Sea cod stock. The 7-year predictions are based on the propagation of ocean temperature anomalies from the subpolar North Atlantic toward the Barents Sea, and the strong co-variability between these temperature anomalies and the cod stock. Retrospective predictions for the period 1957–2017 capture well multi-year to decadal variations in cod stock biomass, with cross-validated explained variance of over 60%. For lead times longer than one year the statistical long-term predictions show more skill than operational short-term predictions used in fisheries management and lagged persistence forecasts. Our results thus demonstrate the potential for ecosystem-based fisheries management, which could enable strategic planning on longer time scales. Future predictions show a gradual decline in the cod stock towards 2024. %0 journal article %@ 2169-9275 %A Tim, N., Zorita, E., Schwarzkopf, F.U., Ruehs, S., Emeis, K.-C., Biastoch, A. %D 2018 %J Journal of Geophysical Research : Oceans %N 12 %P 9416-9428 %R doi:10.1029/2018JC014218 %T The impact of Agulhas leakage on the central water masses in the Benguela upwelling system from a high-resolution ocean simulation %U https://doi.org/10.1029/2018JC014218 12 %X We analyze the contribution of the Agulhas Current on the central water masses of the Benguela upwelling system (BUS) over the last decades in a high‐resolution ocean simulation driven by atmospheric reanalysis. The BUS is an eastern boundary upwelling system where upwelling of cold nutrient‐rich water favors biomass growth. The two distinct subregions, North and South Benguela, differ in nutrient and oxygen properties of the upwelling water mass. Our analysis indicates that the contribution of Agulhas water to the upwelling is very strong in both subregions. Although the water masses feeding the upwelling have a common origin, their pathways are distinct in both regions. Whereas for the central waters of South Benguela the path is rather direct from where it is formed, the central waters of North Benguela takes a longer route through the equatorial current system. Not only the travel time from the Agulhas Current to the BUS is longer but the central water mass is twice as old for the northern part when compared to the southern. Our analysis traces the pathways, history and origin of the central water masses feeding upwelling in the BUS and emphasizes the direct impact of the Agulhas Current on the upwelling region. The variability of that link between the Indian Ocean and the South Atlantic is likely to change the nutrient and oxygen content, as well as temperature and salinity of the water masses in the upwelling region. %0 journal article %@ 1463-5003 %A Stanev, E.V., Pein, J., Grashorn, S., Zhang, Y., Schrum, C. %D 2018 %J Ocean Modelling %P 40-58 %R doi:10.1016/j.ocemod.2018.08.009 %T Dynamics of the Baltic Sea straits via numerical simulation of exchange flows %U https://doi.org/10.1016/j.ocemod.2018.08.009 %X The Semi-implicit Cross-scale Hydroscience Integrated System Model (SCHISM), which uses unstructured grids, is set up for the North and Baltic Seas. With a resolution of ∼100 m in the narrow straits connecting the two basins, this model accurately resolves the inter-basin exchange. Validation against observations in the straits shows the model has good skill in simulating the transport and vertical profiles of temperature, salinity and currents. The timing and magnitude of the major inflow event in 2014–2015 is also realistically simulated. The analysis is focused on the two-layer exchange, its dependence on the atmospheric forcing, and dominant physical balances. The two-layer flows in the three connecting straits show different dependencies upon the net transport. The spatial variability of this dependence is also quite pronounced. The three-strait system developed specific dynamics, with time lags and differences between currents in the individual straits during inflow and outflow conditions. Analysis on the impact of resolution indicates that the performance of the model changes depending on whether the narrow parts of the straits are resolved with a resolution of 500 m or 100 m. With this ultra-fine resolution, gravity flows and variability of salinity in deep layers is generally more adequately simulated. This paper identifies the needs for more profound analysis of the coupled dynamics of Baltic and North Seas with a focus on the Danish straits. %0 journal article %@ 1558-8424 %A Li, D., Yin, B., Feng, J., Dosio, A., Geyer, B., Qi, J., Shi, H., Xu, Z. %D 2018 %J Journal of Applied Meteorology and Climatology %N 10 %P 2317-2341 %R doi:10.1175/JAMC-D-18-0008.1 %T Present Climate Evaluation and Added Value Analysis of Dynamically Downscaled Simulations of CORDEX - East Asia %U https://doi.org/10.1175/JAMC-D-18-0008.1 10 %X In this study, we investigate the skills of the regional climate model Consortium for Small-Scale Modeling in Climate Mode (CCLM) in reproducing historical climatic features and their added value to the driving global climate models (GCMs) of the Coordinated Regional Climate Downscaling Experiment—East Asia (CORDEX-EA) domain. An ensemble of climate simulations, with a resolution of 0.44°, was conducted by downscaling four GCMs: CNRM-CM5, EC-EARTH, HadGEM2, and MPI-ESM-LR. The CCLM outputs were compared with different observations and reanalysis datasets. Results showed strong seasonal variability of CCLM’s ability in reproducing climatological means, variability, and extremes. The bias of the simulated summer temperatures is generally smaller than that of the winter temperatures; in addition, areas where CCLM adds value to the driving GCMs in simulating temperature are larger in the winter than in the summer. CCLM outperforms GCMs in terms of generating climatological precipitation means and daily precipitation distributions for most regions in the winter, but this is not always the case for the summer. It was found that CCLM biases are partly inherited from GCMs and are significantly shaped by structural biases of CCLM. Furthermore, downscaled simulations show added value in capturing features of consecutive wet days for the tropics and of consecutive dry days for areas to the north of 30°N. We found considerable uncertainty from reanalysis and observation datasets in temperatures and precipitation climatological means for some regions that rival bias values of GCMs and CCLM simulations. We recommend carefully selecting reference datasets when evaluating modeled climate means. %0 journal article %@ 1726-4170 %A Kerimoglu, O., Hofmeister, R., Maerz, J., Wirtz, K.W. %D 2017 %J Biogeosciences %N 9 %P 4499-4531 %R doi:10.5194/bg-14-4499-2017 %T The acclimative biogeochemical model of the southern North Sea %U https://doi.org/10.5194/bg-14-4499-2017 9 %X Ecosystem models often rely on heuristic descriptions of autotroph growth that fail to reproduce various stationary and dynamic states of phytoplankton cellular composition observed in laboratory experiments. Here, we present the integration of an advanced phytoplankton growth model within a coupled 3-dimensional physical-biogeochemical model, and the implementation of the model system to the Southern North Sea (SNS) defined on a relatively high resolution (~ 1.5–4.5 km) curvilinear grid. The autotrophic growth model, recently introduced by Wirtz and Kerimoglu (2016), is built up on a set of novel concepts for the allocation of internal resources and operation of cellular metabolism. The coupled model system consists of the general estuarine transport model (GETM) as the hydrodynamical driver, a lower trophic level model and a simple sediment diagenesis model. We force the model system with realistic atmospheric and riverine fluxes, background turbidity caused by suspended particulate matter and open ocean boundary conditions. For a simulation for the period 2000–2010, we show that the model system satisfactorily reproduces the physical and biogeochemical states of the system, as inferred from comparisons against data from long-term monitoring stations, sparse measurements, continuous transects, and remote sensing data. In particular, the model shows high skill both in coastal and off shore waters, and captures the steep gradients in nutrient and chlorophyll concentrations observed prevalently across the coastal transition zone. We show that the cellular chlorophyll to carbon ratio show significant seasonal and lateral variability, the latter amplifying the steepness of the transitional chlorophyll gradient, thus, pointing to the relevance of resolving the physiological acclimation processes for an accurate description of biogeochemical fluxes. %0 journal article %@ 1814-9324 %A Pyrina, M., Wagner, S., Zorita, E. %D 2017 %J Climate of the Past %N 10 %P 1339-1354 %R doi:10.5194/cp-13-1339-2017 %T Pseudo-proxy evaluation of Climate Field Reconstruction methods of North Atlantic climate based on an annually resolved marine proxy network %U https://doi.org/10.5194/cp-13-1339-2017 10 %X Two statistical methods are tested to reconstruct the inter-annual variations of past sea surface temperatures (SSTs) of the North Atlantic (NA) Ocean over the past millennium, based on annually resolved and absolutely dated marine proxy records of the bivalve mollusk Arctica islandica. The methods are tested in a pseudo-proxy experiment (PPE) set-up using state-of-the-art climate models (CMIP5 Earth System Models) and reanalysis data from the COBE2 SST data set. The methods were applied in the virtual reality provided by global climate simulations and reanalysis data to reconstruct the past NA SSTs, using pseudoproxy records that mimic the statistical characteristics and network of Arctica islandica. The multivariate linear regression methods evaluated here are Principal Component Regression and Canonical Correlation Analysis. Differences in the skill of the Climate Field Reconstruction (CFR) are assessed according to different calibration periods and different proxy locations within the NA basin. The choice of the climate model used as surrogate reality in the PPE has a more profound effect on the CFR skill than the calibration period and the statistical reconstruction method. The differences between the two methods are clearer for the MPI-ESM model, due to its higher spatial resolution in the NA basin. The pseudo-proxy results of the CCSM4 model are closer to the pseudo-proxy results based on the reanalysis data set COBE2. The addition of noise in the pseudo-proxies is important for the evaluation of the methods, as more spatial differences in the reconstruction skill are revealed. More profound differences between methods are obtained when the number of proxy records is smaller than five, making the Principal Component Regression a more appropriate method in this case. Despite the differences, the results show that the marine network of Arctica islandica can be used to skilfully reconstruct the spatial patterns of SSTs at the eastern NA basin. %0 journal article %@ 1752-0894 %A Buentgen, U., Myglan, V.S., Ljungqvist, F.C., McCormick, M., Di Cosmo, N., Sigl, M., Jungclaus, J., Wagner, S., Krusic, P.J., Esper, J., kaplan, J.O., de Vaan, M.A.C., Luterbacher, J., Wacker, L., Tegel, W., Solomina, O.N., Nicolussi, K., Oppenheimer, C., Reinig, F., Kirdyanov, A.V. %D 2017 %J Nature Geoscience %P 243 %R doi:10.1038/ngeo2927 %T Reply to 'Limited Late Antique cooling' %U https://doi.org/10.1038/ngeo2927 %X No abstract %0 journal article %@ 1680-7316 %A Gencarelli, C.N., Bieser, J., Carbone, F., De Simone, F., Hedgecock, I.M., matthias, V., Travnikov, O., Yang, X., Pirrone, N. %D 2017 %J Atmospheric Chemistry and Physics %N 1 %P 627-643 %R doi:10.5194/acp-17-627-2017 %T Sensitivity model study of regional mercury dispersion in the atmosphere %U https://doi.org/10.5194/acp-17-627-2017 1 %X Atmospheric deposition is the most important pathway by which Hg reaches marine ecosystems, where it can be methylated and enter the base of food chain. The deposition, the transport and chemical interactions of atmospheric Hg has been simulated over Europe for the year 2013 in the framework of the Global Mercury Observation System (GMOS) project, performing 14 different model sensitivity tests using two high resolution three-dimensional Chemical Transport Models (CTMs), varying the anthropogenic emissions data sets, atmospheric Br input fields, the Hg oxidation schemes and the modelling domain boundary condition input. Sensitivity simulation results were compared with observations from 28 monitoring sites in Europe, to assess model performance and particularly to analyse the influence of anthropogenic emission speciation and the Hg0(g) atmospheric oxidation mechanism. The contribution of anthropogenic Hg emissions, their speciation and vertical distribution is crucial to the simulated concentration and deposition fields, as is also the choice of Hg0(g) oxidation pathway. The areas most sensitive to changes in Hg emission speciation and the emission vertical distribution are those near major sources, but also the Aegean and the Black Seas, the English Channel, the Skagerrak Strait and the North German coast. Considerable influence was found also evident over the Mediterranean, the North and Baltic Sea, some influence is seen over continental Europe, while this difference is least over the north-western part of the modelling domain, which includes the Norwegian Sea and Iceland. The Br oxidation pathway produces more HgII(g) in the lower model levels, but overall wet deposition is lower in comparison to the simulations which employ an O3/OH oxidation mechanism. The necessity to perform continuous measurements of speciated Hg, to investigate the local impacts of Hg emissions and deposition, as well as interactions dependent on land use and vegetation, forests, peat bogs etc. is highlighted in this study. %0 journal article %@ 2299-3835 %A Storch, H.v., Bray, D.G. %D 2017 %J Meteorology, Hydrology and Water Management %N 1 %P 47-52 %R doi:10.26491/mhwm/67388 %T Models, manifestation and attribution of climate change %U https://doi.org/10.26491/mhwm/67388 1 %X We stress that the presented results concern the opinion of climate scientists with a rather broad background. Our results do not assess if the opinions of the surveyed scientists are “valid” or “right”, but they recognize the character of science being a social process. %0 journal article %@ 1814-9324 %A Dallmeyer, A., Claussen, M., Ni, J., Cao, X., Wang, Y., Fischer, N., Pfeiffer, M., Jin, L., Khon, V., Wagner, S., Haberkorn, K., Herzschuh, U. %D 2017 %J Climate of the Past %N 2 %P 107-134 %R doi:10.5194/cp-13-107-2017 %T Biome changes in Asia since the mid-Holocene – An analysis of different transient Earth system model simulations %U https://doi.org/10.5194/cp-13-107-2017 2 %X In all simulations, substantial biome shifts during the last 6000 years are confined to the high northern latitudes and the monsoon–westerly wind transition zone, but the temporal evolution and amplitude of change strongly depend on the climate forcing. Large parts of the southern tundra are replaced by taiga during the mid-Holocene due to a warmer growing season and the boreal treeline in northern Asia is shifted northward by approx. 4° in the ensemble mean, ranging from 1.5 to 6° in the individual simulations, respectively. This simulated treeline shift is in agreement with pollen-based reconstructions from northern Siberia. The desert fraction in the transition zone is reduced by 21 % during the mid-Holocene compared to pre-industrial due to enhanced precipitation. The desert–steppe margin is shifted westward by 5° (1–9° in the individual simulations). The forest biomes are expanded north-westward by 2°, ranging from 0 to 4° in the single simulations. These results corroborate pollen-based reconstructions indicating an extended forest area in north-central China during the mid-Holocene. According to the model, the forest-to-non-forest and steppe-to-desert changes in the climate transition zones are spatially not uniform and not linear since the mid-Holocene. %0 journal article %@ 0027-0644 %A Schubert-Frisius, M., Feser, F., Storch, H.v., Rast, S. %D 2017 %J Monthly Weather Review %N 3 %P 909-927 %R doi:10.1175/MWR-D-16-0036.1 %T Optimal Spectral Nudging for Global Dynamical Downscaling %U https://doi.org/10.1175/MWR-D-16-0036.1 3 %X This study analyzes a method to construct a homogeneous, high-resolution global atmospheric hindcast. The method is the spectral nudging technique which was applied to a state-of-the-art general circulation model (ECHAM6, T255L95). Large spatial scales of the global climate model prognostic variables were spectrally nudged towards a reanalysis data set (NCEP1, T62L28) for the last decades. The main idea is the addition of dynamically consistent regional weather details to the coarse grid NCEP1 reanalysis. A large number of sensitivity experiments were performed, using different nudging e-folding times, vertical profiles, wave numbers, and variables. Comparisons with observations and several reanalyses showed a high dependency on the variations of the nudging configuration. At the global scale, the accordance is very high for extra-tropical regions and lower in the tropics. A wave number truncation of 30, a relatively short e-folding time of 50 min and a plateau-shaped nudging profile applied only to divergence and vorticity generally yielded the best results. This is one of the first global spectral nudging hindcast studies and the first applying an altitude-dependent profile to selected prognostic variables. The method can be applied to reconstruct the history of extreme events such as intense storms in the context of ongoing climate change. %0 journal article %@ 1680-7316 %A Solazzo, E., Bianconi, R., Hogrefe, C., Curci, G., Alyuz, U., Balzarini, A., Baro, R., Bellasio, R., Bieser, J., Brandt, J., Christensen, J.H., Colette, A., Francis, X., Fraser, A., Garcia Vivanco, M., Jimenez-Guerrero, P., Im, U., Manders, A., Nopmongcol, U., Kitwiroon, N., Pirovano, G., Pozzoli, L., Prank, M., Sokhi, R.S., Tuccella, P., Unal, A., Yarwood, G., Galmarini, S. %D 2017 %J Atmospheric Chemistry and Physics %N 4 %P 3001-3054 %R doi:10.5194/acp-17-3001-2017 %T Evaluation and error apportionment of an ensemble of atmospheric chemistry transport modeling systems: multivariable temporal and spatial breakdown %U https://doi.org/10.5194/acp-17-3001-2017 4 %X The application of the error apportionment method to the AQMEII Phase 3 simulations provides several key insights. In addition to reaffirming the strong impact of model inputs (emissions and boundary conditions) and poor representation of the stable boundary layer on model bias, results also highlighted the high inter-dependencies among meteorological and chemical variables, as well as among their errors. This indicates that the evaluation of air quality model performance for individual pollutants needs to be supported by complementary analysis of meteorological fields and chemical precursors to provide results that are more insightful from a model development perspective. The error embedded in the emissions is dominant for primary species (CO, PM, NO) and largely outweighs the error from any other source. The uncertainty in meteorological fields is most relevant to ozone. Some further aspects emerged whose interpretation requires additional consideration, such as, among others, the uniformity of the synoptic error being region and model-independent, observed for several pollutants; the source of unexplained variance for the diurnal component; and the type of error caused by deposition and at which scale. %0 journal article %@ 0964-5691 %A Gonzalez-Riancho, P., Gerkensmeier, B., Ratter, B.M.W. %D 2017 %J Ocean and Coastal Management %P 118-131 %R doi:10.1016/j.ocecoaman.2017.03.006 %T Storm surge resilience and the Sendai Framework: Risk perception, intention to prepare and enhanced collaboration along the German North Sea coast %U https://doi.org/10.1016/j.ocecoaman.2017.03.006 %X This work assesses the capacity of the German North Sea coast community, which has been hit by several disastrous storm surge events in the past, to organise itself before, during, and after storm surge events in order to minimise the impacts. By means of a survey-based method, we explore stakeholders' perception regarding the risk and emergency management processes, the psychological and social factors conditioning the intention to prepare and collaborate, as well as the feasibility of enhanced coordination and collaboration mechanisms at the community level. Acknowledging past and ongoing successful initiatives in the study area, the method allows identifying opportunities to foster preparedness and adaptation, such as an improved risk communication strategy, mainstreaming and integrating risk reduction within and across sectors, and the transition from basic participatory approaches based solely on information provision towards full involvement and collaborative approaches. The major findings of the study represent an initial diagnostic to help meet the guidelines and priorities proposed in the recent Sendai Framework for Disaster Risk Reduction 2015–2030. %0 journal article %@ 1463-5003 %A Schloen, J., Stanev, E., Grashorn, S. %D 2017 %J Ocean Modelling %P 19-37 %R doi:10.1016/j.ocemod.2017.01.003 %T Wave-current interactions in the southern North Sea: The impact on salinity %U https://doi.org/10.1016/j.ocemod.2017.01.003 %X The interplay between wind waves and currents in the coastal zone of the southern North Sea along with the resulting changes in the salinity distribution are quantified using simulations with the unstructured-grid ocean model SCHISM coupled with the wind wave model WWM III. Several sensitivity runs, which are carried out to estimate the individual contributions of different physical mechanisms and forcing, demonstrated that the density gradients in the coastal zone reduce tidal current by 18%, whereas the wind waves enhance the circulation in some cases. The latter happens when along-shore wind speed approaches ∼10 m s resulting in long-shore currents following the western Dutch coast and the German Wadden Sea islands. The wave-induced transport of salt leads to changes in the horizontal salinity distribution. These are most pronounced in front of barrier islands where coherent patterns caused by the coupling between tides, surface drift, and wind waves reveal salinity changes up to 0.5. The weak stratification of salinity in the coastal zone is mostly destroyed by wind waves. Thus, effects created by wind waves tend to substantially modify the estuarine circulation. An explanation of these important processes in the coastal zone has been given based on an analysis of the ratio between significant wave height and tidal range. This control-parameter, which is relatively small under mild weather conditions, can exceed unity under strong wind conditions in the coastal zone, thus mixing due to waves becomes dominant. The effect of fresh water fluxes from subterranean estuaries is relatively small and confined only in the vicinity of corresponding sources. %0 journal article %@ 2225-1154 %A Karabil, S. %D 2017 %J Climate %N 3 %P 71 %R doi:10.3390/cli5030071 %T Influence of Atmospheric Circulation on the Baltic Sea Level Rise under the RCP8.5 Scenario over the 21st Century %U https://doi.org/10.3390/cli5030071 3 %X This study aims to estimate the influence of atmospheric circulation modes on future Baltic Sea level rise under the Representative Concentration Pathway 8.5 (RCP8.5) climate scenario for the period 2006–2100. For this estimation, the connection between the sea level variations in two selected representative locations—Stockholm and Warnemünde, and two atmospheric indices—the Baltic Sea and North Sea Oscillation (BANOS) index and the North Atlantic Oscillation (NAO) index is statistically analysed. Correlations of winter means between atmospheric indices, BANOS and NAO, and tide gauges are measured as 0.85 and 0.55 for Stockholm, and 0.55 and 0.17 for Warnemünde over the period 1900–2013. Assuming that the established connection remains unchanged, the influence of atmospheric circulation modes on future Baltic Sea level rise is estimated from the projections of atmospheric indices, which are constructed from the SLP outputs of climate models participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5) under the RCP8.5 scenario. The main conclusion is that the contribution of those atmospheric modes to the Baltic Sea level rise is likely to remain small over the 21st century. Additionally, corresponding trend estimations of model realizations indicate the large influence of the internal climatic variability of the CMIP5 models on those future trends. One of the most important findings of this study is that anthropogenic forcing does not play a key role in the evolution of these atmospheric indices. %0 journal article %@ 2190-4979 %A Daewel, U., Schrum, C. %D 2017 %J Earth System Dynamics %N 3 %P 801-815 %R doi:10.5194/esd-8-801-2017 %T Low-frequency variability in North Sea and Baltic Sea identified through simulations with the 3-D coupled physical–biogeochemical model ECOSMO %U https://doi.org/10.5194/esd-8-801-2017 3 %X Here we present results from a long-term model simulation of the 3-D coupled ecosystem model ECOSMO II for a North Sea and Baltic Sea set-up. The model allows both multi-decadal hindcast simulation of the marine system and specific process studies under controlled environmental conditions. Model results have been analysed with respect to long-term multi-decadal variability in both physical and biological parameters with the help of empirical orthogonal function (EOF) analysis. The analysis of a 61-year (1948–2008) hindcast reveals a quasi-decadal variation in salinity, temperature and current fields in the North Sea in addition to singular events of major changes during restricted time frames. These changes in hydrodynamic variables were found to be associated with changes in ecosystem productivity that are temporally aligned with the timing of reported regime shifts in the areas. Our results clearly indicate that for analysing ecosystem productivity, spatially explicit methods are indispensable. Especially in the North Sea, a correlation analysis between atmospheric forcing and primary production (PP) reveals significant correlations between PP and the North Atlantic Oscillation (NAO) and wind forcing for the central part of the region, while the Atlantic Multi-decadal Oscillation (AMO) and air temperature are correlated to long-term changes in PP in the southern North Sea frontal areas. Since correlations cannot serve to identify causal relationship, we performed scenario model runs perturbing the temporal variability in forcing condition to emphasize specifically the role of solar radiation, wind and eutrophication. The results revealed that, although all parameters are relevant for the magnitude of PP in the North Sea and Baltic Sea, the dominant impact on long-term variability and major shifts in ecosystem productivity was introduced by modulations of the wind fields. %0 journal article %@ 0340-4552 %A Rockel, B., Brauch, J., Gutjahr, O., Akhtar, N., Ho-Hagemann, H.T.M. %D 2017 %J Promet %P 65-75 %T Gekoppelte regionale Atmosphaeren-Ozean Modellsysteme %U %X Regional coupled atmosphere-ocean systems contribute through their mutual exchange of information to a consistent view on the regional climate system. In this chapter different types of coupling of regional atmosphere- and ocean models are described. Based on four rather different maritime seas (Mediterranean, North Sea, Baltic Sea and Arctic Ocean) the specific requirements of these seas to coupled atmosphere-ocean model systems are described. This is complemented by examples taken from scientific practice. %0 journal article %@ 1992-0636 %A Meinke, I. %D 2017 %J Advances in Science and Research %P 145-151 %R doi:10.5194/asr-14-145-2017 %T On the comparability of knowledge transfer activities – a case study at the German Baltic Sea Coast focusing regional climate services %U https://doi.org/10.5194/asr-14-145-2017 %X It is suggested to account for the described external impacts for evaluations of knowledge transfer activities. The results show that the comparability of knowledge transfer activities is limited and challenge the adequacy of quantitative measures in this context. Moreover, as shown in this case study, in particular regional climate services should be individually evaluated on a long term perspective, by potential user groups and/or by its real users. It is further suggested that evaluation criteria should be co-developed with these stakeholder groups. %0 journal article %@ 1991-959X %A Will, A., Akhtar, N., Brauch, J., Breil, M., Davin, E., Ho-Hagemann, H.T.M., Maisonnave, E., Thuerkow, M., Weiher, S. %D 2017 %J Geoscientific Model Development %N 4 %P 1549-1586 %R doi:10.5194/gmd-10-1549-2017 %T The COSMO-CLM 4.8 regional climate model coupled to regional ocean, land surface and global earth system models using OASIS3-MCT: description and performance %U https://doi.org/10.5194/gmd-10-1549-2017 4 %X OASIS3-MCT remains below 7% of the CCLM stand-alone cost for all couplings investigated. This is in particular true for the exchange of 450 2D fields between CCLM and MPI-ESM. We identified remaining limitations in the coupling strategies and discuss possible future improvements of the computational efficiency. %0 journal article %@ 1680-7316 %A Travnikov, O., Angot, H., Artaxo, P., Bencardino, M., Bieser, J., D`Àmore, F., Dastoor, A., De Simone, F., del Carmen Dieguez, M., Dommergue, A., Ebinghaus, R., Feng, X.B., Gencarelli, C.N., Hedgecock, I.M., Magand, O., Martin, L., Matthias, V., Mashyanov, N., Pirrone, N., Ramachandran, R., Read, K.A., Ryjkov, A., Selin, N.E., Sena, F., Song, S., Sprovieri, F., Wip, D., Waengberg, I., Yang, X. %D 2017 %J Atmospheric Chemistry and Physics %N 8 %P 5271-5295 %R doi:10.5194/acp-17-5271-2017 %T Multi-model study of mercury dispersion in the atmosphere: Atmospheric processes and model evaluation %U https://doi.org/10.5194/acp-17-5271-2017 8 %X Current understanding of mercury (Hg) behaviour in the atmosphere contains significant gaps. Some key characteristics of Hg processes including anthropogenic and geogenic emissions, atmospheric chemistry, and air-surface exchange are still poorly known. This study provides a complex analysis of processes governing Hg fate in the atmosphere involving both measurement data from ground-based sites and simulation results of chemical transport models. A variety of long-term measurements of gaseous elemental Hg (GEM) and reactive Hg (RM) concentration as well as Hg wet deposition flux has been compiled from different global and regional monitoring networks. Four contemporary global-scale transport models for Hg were applied both in their state-of-the-art configurations and for a number of numerical experiments aimed at evaluation of particular processes. Results of the model simulation were evaluated against measurements. As it follows from the analysis the inter-hemispheric gradient of GEM is largely formed by the spatial distribution of anthropogenic emissions which prevail in the Northern Hemisphere. Contribution of natural and secondary emissions enhances the south-to-north gradient but their effect is less significant. The atmospheric chemistry does not affect considerably both spatial distribution and temporal variation of GEM concentration in the surface air. On the other hand, RM air concentration and wet deposition are largely defined by oxidation chemistry. The Br oxidation mechanism allows successfully reproducing observed seasonal variation of the RM / GEM ratio in the near-surface layer, whereas it predicts maximum in wet deposition in spring instead of summer as observed at monitoring sites located in North America and Europe. Model runs with the OH chemistry correctly simulate both the periods of maximum and minimum values and the amplitude of observed seasonal variation but lead to shifting the maximum RM / GEM ratios from spring to summer. The O3 chemistry does not provide significant seasonal variation of Hg oxidation. Thus, performance of the considered Hg oxidation mechanisms differs in reproduction of different observed parameters that can imply possibility of more complex chemistry and multiple pathways of Hg oxidation occurring concurrently in various parts of the atmosphere. %0 journal article %@ 0894-8755 %A Buentgen, U., Krusik, P.J., Verstege, A., Sanguesa Barreda, G., Wagner, S., Camarero, J.J., Ljungqvist, F.C., Zorita, E., Oppenheimer, C., Konter, O., Tegel, W., Gaertner, H., Cherubini, P., Reinig, F., Esper, J. %D 2017 %J Journal of Climate %N 14 %P 5295-5318 %R doi:10.1175/JCLI-D-16-0526.1 %T New Tree-Ring Evidence from the Pyrenees Reveals Western Mediterranean Climate Variability since Medieval Times %U https://doi.org/10.1175/JCLI-D-16-0526.1 14 %X Paleoclimatic evidence is necessary to place the current warming and drying of the western Mediterranean basin in a long-term perspective of natural climate variability. Annually resolved and absolutely dated temperature proxies south of the European Alps that extend back into medieval times are, however, mainly limited to measurements of maximum latewood density (MXD) from high-elevation conifers. Here, we present the world’s best replicated MXD site chronology of 414 living and relict Pinus uncinata trees found >2200 m asl in the Spanish central Pyrenees. This composite record correlates significantly (p ≤0.01) with May-June and August-September mean temperatures over most of the Iberian Peninsula and northern Africa (r =0.72 1950-2014). Spanning the period 1186-2014 CE, the new reconstruction reveals overall warmer conditions around 1200 and 1400, and again after ~1850. The coldest reconstructed summer in 1258 (-4.4°C wrt 1961-1990) followed the largest known volcanic eruption of the CE. The 20th century is characterized by pronounced summer cooling in the 1970s, subsequently rising temperatures until 2003, and a slowdown of warming afterwards. Little agreement is found with climate model simulations that consistently overestimate recent summer warming and underestimate pre-industrial temperature changes. Interannual to multi-decadal co-variability with regional hydroclimate includes summer pluvials after large volcanic eruptions. Our study demonstrates the relevance of updating MXD-based temperature reconstructions, not only back in time but also towards the present, and emphasizes the importance of comparing temperature and hydroclimatic proxies, as well as model simulations for understanding regional climate dynamics. %0 journal article %@ 1811-1602 %A Abram, N., Bothe, O., Linderholm, H., Mertrant, B., Mc Gregor, H., Neukom, R., Phipps, S., St George, S., Gunten, L.v. %D 2017 %J Past Global Changes Magazine %N 1 %P 71-74 %R doi:10.22498/pages.25.1.71 %T The third phase of the PAGES 2k Network %U https://doi.org/10.22498/pages.25.1.71 1 %X The past 2000 years (the “2k” interval) provides critical context for our understanding of recent anthropogenic forcing of the climate, as well as baseline information about Earth’s natural climate variability. It also provides opportunities to improve the interpretation of paleoclimate proxy observations, and to perform out-of-sample evaluation of the climate and earth system models that are used to generate projections of future climate change. %0 journal article %@ 1726-4170 %A Moreno de Castro, M., Schartau, M., Wirtz, K. %D 2017 %J Biogeosciences %N 7 %P 1883-1901 %R doi:10.5194/bg-14-1883-2017 %T Potential sources of variability in mesocosm experiments on the response of phytoplankton to ocean acidification %U https://doi.org/10.5194/bg-14-1883-2017 7 %X Mesocosm experiments on phytoplankton dynamics under high CO2 concentrations mimic the response of marine primary producers to future ocean acidification. However, potential acidification effects can be hindered by the high standard deviation typically found in the replicates of the same CO2 treatment level. In experiments with multiple unresolved factors and a sub-optimal number of replicates, post-processing statistical inference tools might fail to detect an effect that is present. We propose that in such cases, data-based model analyses might be suitable tools to unearth potential responses to the treatment and identify the uncertainties that could produce the observed variability. As test cases, we used data from two independent mesocosm experiments. Both experiments showed high standard deviations and, according to statistical inference tools, biomass appeared insensitive to changing CO2 conditions. Conversely, our simulations showed earlier and more intense phytoplankton blooms in modeled replicates at high CO2 concentrations and suggested that uncertainties in average cell size, phytoplankton biomass losses, and initial nutrient concentration potentially outweigh acidification effects by triggering strong variability during the bloom phase. We also estimated the thresholds below which uncertainties do not escalate to high variability. This information might help in designing future mesocosm experiments and interpreting controversial results on the effect of acidification or other pressures on ecosystem functions. %0 journal article %@ 1951-6355 %A Siekmann, I., Bengfort, M., Malchow, H. %D 2017 %J The European Physical Journal - Special Topics %N 9 %P 2157-2170 %R doi:10.1140/epjst/e2017-70038-6 %T Coexistence of competitors mediated by nonlinear noise %U https://doi.org/10.1140/epjst/e2017-70038-6 9 %X Stochastic reaction-diffusion equations are a popular modelling approach for studying interacting populations in a heterogeneous environment under the influence of environmental fluctuations. Although the theoretical basis of alternative models such as Fokker-Planck diffusion is not less convincing, movement of populations is most commonly modelled using the diffusion law due to Fick. An interesting feature of Fokker-Planck diffusion is the fact that for spatially varying diffusion coefficients the stationary solution is not a homogeneous distribution – in contrast to Fick’s law of diffusion. Instead, concentration accumulates in regions of low diffusivity and tends to lower levels for areas of high diffusivity. Thus, we may interpret the stationary distribution of the Fokker-Planck diffusion as a reflection of different levels of habitat quality. Moreover, the most common model for environmental fluctuations, linear multiplicative noise, is based on the assumption that individuals respond independently to stochastic environmental fluctuations. For large population densities the assumption of independence is debatable and the model further implies that noise intensities can increase to arbitrarily high levels. Therefore, instead of the commonly used linear multiplicative noise model, we implement environmental variability by an alternative nonlinear noise term which never exceeds a certain maximum noise intensity. With Fokker-Planck diffusion and the nonlinear noise model replacing the classical approaches we investigate a simple invasive system based on the Lotka-Volterra competition model. We observe that the heterogeneous stationary distribution generated by Fokker-Planck diffusion generally facilitates the formation of segregated habitats of resident and invader. However, this segregation can be broken by nonlinear noise leading to coexistence of resident and invader across the whole spatial domain, an effect that would not be possible in the non-spatial version of the competition model for the parameters considered here. %0 journal article %@ 1476-945X %A Bengfort, M., Velzen, E.van, Gaedke, U. %D 2017 %J Ecological Complexity %P 115-124 %R doi:10.1016/j.ecocom.2017.06.003 %T Slight phenotypic variation in predators and prey causes complex predator-prey oscillations %U https://doi.org/10.1016/j.ecocom.2017.06.003 %X Predator-prey oscillations are expected to show a 1/4-phase lag between predator and prey. However, observed dynamics of natural or experimental predator-prey systems are often more complex. A striking but hardly studied example are sudden interruptions of classic 1/4-lag cycles with periods of antiphase oscillations, or periods without any regular predator-prey oscillations. These interruptions occur for a limited time before the system reverts to regular 1/4-lag oscillations, thus yielding intermittent cycles. Reasons for this behaviour are often difficult to reveal in experimental systems. Here we test the hypothesis that such complex dynamical behaviour may result from minor trait variation and trait adaptation in both the prey and predator, causing recurrent small changes in attack rates that may be hard to capture by empirical measurements. Using a model structure where the degree of trait variation in the predator can be explicitly controlled, we show that a very limited amount of adaptation resulting in 10–15% temporal variation in attack rates is already sufficient to generate these intermittent dynamics. Such minor variation may be present in experimental predator-prey systems, and may explain disruptions in regular 1/4-lag oscillations. %0 journal article %@ 0930-7575 %A Barcikowska, M., Feser, F., Zhang, W., Mei, W. %D 2017 %J Climate Dynamics %N 9-10 %P 2931-2949 %R doi:10.1007/s00382-016-3420-0 %T Changes in intense tropical cyclone activity for the western North Pacific during the last decades derived from a regional climate model simulation %U https://doi.org/10.1007/s00382-016-3420-0 9-10 %X An atmospheric regional climate model (CCLM) was employed to dynamically downscale atmospheric reanalyses (NCEP/NCAR 1, ERA 40) over the western North Pacific and South East Asia. This approach is used for the first time to reconstruct a tropical cyclone climatology, which extends beyond the satellite era and serves as an alternative data set for inhomogeneous observation-derived records (Best Track Data sets). The simulated TC climatology skillfully reproduces observations of the recent decades (1978–2010), including spatial patterns, frequency, lifetime, trends, variability on interannual and decadal time scales and their association with the large-scale circulation patterns. These skills, facilitated here with the spectral nudging method, seem to be a prerequisite to understand the factors determining spatio-temporal variability of TC activity over the western North Pacific. Long-term trends (1948–2011 and 1959–2001) in both simulations show a strong increase of intense tropical cyclone activity. This contrasts with pronounced multidecadal variations found in observations. The discrepancy may partly originate from temporal inhomogeneities in atmospheric reanalyses and Best Track Data, which affect both the model-based and observational-based trends. An adjustment, which removes the simulated upward trend, reduces the apparent discrepancy. Ultimately, our observational and modeling analysis suggests an important contribution of multi-decadal fluctuations in the TC activity during the last six decades. Nevertheless, due to the uncertainties associated with the inconsistencies and quality changes of those data sets, we call for special caution when reconstructing long-term TC statistics either from atmospheric reanalyses or Best Track Data. %0 journal article %@ 1040-6182 %A Gronenborn, D., Strien, H.-C., Lemmen, C. %D 2017 %J Quaternary International %P 54-65 %R doi:10.1016/j.quaint.2017.01.018 %T Population dynamics, social resilience strategies, and Adaptive Cycles in early farming societies of SW Central Europe %U https://doi.org/10.1016/j.quaint.2017.01.018 %X Inferred European Holocene population size exhibits large fluctuations, particularly around the onset of farming. We attempt to find explanations for these fluctuations by employing the concept of cycling, especially that of the Adaptive Cycle. We base our analysis on chronologically and chorologically highly resolved ceramic and site data from the Linear Pottery culture (Germ. Linearbandkermik) of the early Neolithic of southwestern Central Europe. Typological seriation with dendrochronological anchor dates provides the age model for these data. Ceramic motifs are analysed with respect to the temporally changing diversity in decoration. The temporal sequence of major decoration motifs is interpreted as an indicator of social diversity: when stylistic diversity is low, social diversity is low and vice versa. The sequence of secondary decoration motifs is interpreted in terms of individual lineage emphasis: when this diversity is low, there is strong emphasis on individual lineage and vice versa. The diversity time series are complemented by a relative population size indicator derived from the count of occupational features. Diversity and population size share a shape that is typical for (part of) an Adaptive Cycle, and they differ in their positioning on the time axis — they are time-lagged. By relating the different curves to the (metaphorical) stages of the Adaptive Cycle, we find that these cycles progress at non-identical speed in different aspects of a social system. By relating the social dynamics to well-dated and highly resolved climate fluctuation records, we find evidence that severe climate excursions shaped the location of tipping points in the social system and that these social tipping points precede inferred population decline by several generations. %0 journal article %@ 1680-7316 %A Bieser, J., Slemr, F., Ambrose, J., Brenninkmeijer, C., Brooks, S., Dastoor, A., De Simone, F., Ebinghaus, R., Gencarelli, C., Geyer, B., Gratz, L.E., Hedgecock, I.M., Jaffe, D., Kelley, P., Lin, C.-J., Matthias, V., Ryjkov, A., Selin, N., Song, S., Travnikov, O., Weigelt, A., Luke, W., Ren, X., Zahn, A., Yang, X., Zhu, Y., Pirrone, N. %D 2017 %J Atmospheric Chemistry and Physics %N 11 %P 6925-6955 %R doi:10.5194/acp-17-6925-2017 %T Multi-model study of mercury dispersion in the atmosphere: Vertical distribution of mercury species %U https://doi.org/10.5194/acp-17-6925-2017 11 %X The investigated models proved to be able to reproduce the distribution of total and elemental mercury concentrations in the troposphere including interhemispheric trends. One key aspect of the study is the investigation of mercury oxidation in the troposphere. We found that different chemistry schemes were better at reproducing observed oxidized mercury patterns depending on altitude. High concentrations of oxidized mercury in the upper troposphere could be reproduced with oxidation by bromine while elevated concentrations in the lower troposphere were better reproduced by OH and ozone chemistry. However, the results were not always conclusive as the physical and chemical parameterizations in the chemistry transport models also proved to have a substantial impact on model results. %0 journal article %@ 0930-7575 %A Pyrina, M., Wagner, S., Zorita, E. %D 2017 %J Climate Dynamics %N 11-12 %P 3673-3691 %R doi:10.1007/s00382-017-3536-x %T Evaluation of CMIP5 models over the northern North Atlantic in the context of forthcoming paleoclimatic reconstructions %U https://doi.org/10.1007/s00382-017-3536-x 11-12 %X We evaluated 11 coupled climate model simulations regarding the spatial structures of sea-surface temperature (SST) variability in the North Atlantic, during the second half of the twentieth century. The subset of models includes CCSM4, CSIRO, CanESM and MPI-ESM, participating in the fifth phase of the Climate Model Intercomparison Project. The evaluation was performed to determine the potential of these models to be used at a later stage as test beds for the evaluation of climate field reconstruction methods that will use the extremely long-lived bivalve mollusk Arctica islandica, an outstanding paleoclimate archive for the boreal and temperate North Atlantic (Schöne, Glob Planet Change 111:199–225, 2013). Several validation metrics such as the mean bias, variance, spatial and temporal co-variability and trends of the North Atlantic summer SSTs showed that some of the models can be used to test paleoclimatic reconstructions. However, most models showed shortcomings in simulating the Atlantic Multidecadal Oscillation. Concerning the co-variability of summer SSTs between proxy sites and the whole North Atlantic SST field, we found that these proxy locations contain a SST signal that might represent a (basin-wide) signal for the north-eastern North Atlantic basin. %0 journal article %@ 1812-0784 %A Wahle, K., Staneva, J., Koch, W., Fenoglio-Marc, L., Ho-Hagemann, H.T.M., Stanev, E.V. %D 2017 %J Ocean Science %N 2 %P 289-301 %R doi:10.5194/os-13-289-2017 %T An atmosphere-wave regional coupled model: improving predictions of wave heights and surface winds in the southern North Sea %U https://doi.org/10.5194/os-13-289-2017 2 %X The coupling of models is a commonly used approach when addressing the complex interactions between different components of earth systems. We demonstrate that this approach can result in a reduction of errors in wave forecasting, especially in dynamically complicated coastal ocean areas, such as the southern part of the North Sea – the German Bight. Here, we study the effects of coupling of an atmospheric model (COSMO) and a wind wave model (WAM), which is enabled by implementing wave-induced drag in the atmospheric model. The numerical simulations use a regional North Sea coupled wave–atmosphere model as well as a nested-grid high-resolution German Bight wave model. Using one atmospheric and two wind wave models simultaneously allows for study of the individual and combined effects of two-way coupling and grid resolution. This approach proved to be particularly important under severe storm conditions as the German Bight is a very shallow and dynamically complex coastal area exposed to storm floods. The two-way coupling leads to a reduction of both surface wind speeds and simulated wave heights. In this study, the sensitivity of atmospheric parameters, such as wind speed and atmospheric pressure, to the wave-induced drag, in particular under storm conditions, and the impact of two-way coupling on the wave model performance, is quantified. Comparisons between data from in situ and satellite altimeter observations indicate that two-way coupling improves the simulation of wind and wave parameters of the model and justify its implementation for both operational and climate simulations. %0 journal article %@ 0027-0644 %A Schaaf, B., Storch, H.v., Feser, F. %D 2017 %J Monthly Weather Review %N 10 %P 4303-4311 %R doi:10.1175/MWR-D-17-0087.1 %T Does Spectral Nudging Have an Effect on Dynamical Downscaling Applied in Small Regional Model Domains? %U https://doi.org/10.1175/MWR-D-17-0087.1 10 %X In this article, we examine if spectral nudging is having an effect on simulations with model regions of the size of about 700 km x 500 km at mid-latitudes located mainly over flat terrain. We first compare two pairs of simulations, two runs each with and without spectral nudging, and find that the four simulations are very similar, without systematic or intermittent phases of divergence. Smooth fields, which are mainly determined by spatial patterns, such as air pressure show hardly any differences, while small-scale and heterogeneous fields such as precipitation vary strongly, mostly on the grid-point scale, irrespective if spectral nudging is employed or not. We conclude that the application of spectral nudging has little effect on the simulation when the model region is relatively small. %0 journal article %@ 1992-0636 %A Meinke, I. %D 2017 %J Advances in Science and Research %P 279-291 %R doi:10.5194/asr-14-279-2017 %T Stakeholder-based evaluation categories for regional climate services – A case study at the German Baltic Sea coast %U https://doi.org/10.5194/asr-14-279-2017 %X In this study, categories, dimensions, and criteria for evaluating regional climate services are derived by a participatory approach with potential service users at the German Baltic Sea coast. The development is carried out within nine face-to-face interviews conducted with decision makers, working in climate sensitive sectors at the German Baltic Sea coast. Three main groups of categories were localized which seem to matter most to the considered stakeholders and which seem to be crucial evaluation categories for regional climate services: (1) credibility, (2) relevance, and (3) appropriateness. For each of these evaluation categories several dimensions emerged, indicating certain perspectives of stakeholder demands. When summarizing these evaluation categories and their dimensions, 13 evaluation criteria for regional climate services can be derived (see Table 1). The results show that stakeholders do mainly address components other than those found in the literature (e.g. inputs, process, outputs, outcomes, and impacts). This might indicate that an evaluation, following solely literature-based (non-participative) components, is not sufficient to localize deficiencies or efficiencies within a regional climate service, since it might lead to results which are not relevant for potential users. %0 journal article %@ 0749-0208 %A Evadzi, P.I.K., Zorita, E., Huenicke, B. %D 2017 %J Journal of Coastal Research %N 6 %P 1283-1291 %R doi:10.2112/JCOASTRES-D-16-00119.1 %T Quantifying and Predicting the Contribution of Sea-Level Rise to Shoreline Change in Ghana: Information for Coastal Adaptation Strategies %U https://doi.org/10.2112/JCOASTRES-D-16-00119.1 6 %X The purpose of this study is to estimate the contribution of sea-level rise (SLR) in Ghana over the last decades and provide an estimation of shoreline retreat due to the projections of regional SLR. This study first analyzes historical shoreline change in Ghana from 1974 to 2015 using satellite images and orthophotos. Second, this study quantifies the SLR contribution to historical shoreline change using sea-level trend estimates from satellite observations, results from digital elevation model analysis, and shoreline change rates. This study finally makes predictions of shoreline in Ghana on the basis of modified Intergovernmental Panel on Climate Change Fifth Assessment Report representative concentration pathways (RCPs) scenarios for Ghana. On average, sea level has risen by about 5.3 cm over the last 21 years and accounts for only 31% of the observed annual coastal erosion rate (about 2 m/y) in Ghana. On the basis of the projected model ensemble-mean rise in sea-level (2.6, 4.5, and 8.5 RCPs) scenarios and assuming that SLR will also contribute to 31% of shoreline retreat in the future, by the year 2025, about 6.6, 4.7, and 5.8 m of coastland in Ghana with lowest slope range (0–0.4%) are projected to be inundated respectively. These projected changes increase to 19.8, 20.7, and 24.3 m by 2050 and further to 36.6, 51.6, and 83.9 m by 2100 for the 2.6, 4.5, and 8.5 RCPs respectively. The analysis that separates sea-level contribution to coastal change from other contributing factors could provide useful information about climate impact for coastal adaptation strategies. This study, however, recommends further research into the anthropogenic and other factors that contribute about 69% of the annual erosion rate in Ghana to help improve adaptation efforts. %0 journal article %@ 1239-6095 %A Groll, N., Grabemann, I., Huenicke, B., Meese, M. %D 2017 %J Boreal Environment Research %P 1-12 %T Baltic Sea wave conditions under climate change scenarios %U %X Anthropogenic climate change can alter the wind- and sea-ice climate and thus the wave conditions in the Baltic Sea. Here, transient simulations with the 3rd generation wave model WAM under two IPCC AR4 emission scenarios (A1B and B1) and two initial conditions of the forcing atmospheric fields are analyzed for the period 1961–2100. Future changes in the wave climate comprise higher significant wave height for most regions and simulations. Median waves show temporal and spatial consistent changes, whereas extreme waves (99th percentile and maximum) show much more variability in space and among the simulations. These changes in the wave fields result from not only higher wind speeds but also from a shift to more westerly winds, which leads to different fetch and thus to different significant wave height and direction. The multi-decadal and the inter-simulation variability illustrate the uncertainty in the estimation of the climate change signal. %0 journal article %@ 1811-1602 %A Abram, N., Bothe, O., Linderholm, H., Mertrant, B., Mc Gregor, H., Neukom, R., Phipps, S., St George, S., Gunten, L.v. %D 2017 %J Past Global Changes Magazine %N 2 %P 110 %R doi:10.22498/pages.25.2.110 %T Understanding the climate of the past 2000 years: Phase 3 of the PAGES 2k Network %U https://doi.org/10.22498/pages.25.2.110 2 %X The PAGES 2k Network was created with the aim of reconstructing changes in regional and global surface climate over the past 2000 years. During Phases 1 (2008-2013) and 2 (2014-2016), regional and trans-regional groupings focused on building reconstructions for terrestrial regions and the oceans. The conclusion of Phase 2 coincided with the release of an open and transparent global database of temperature-sensitive proxies spanning the Common Era (Fig. 1; PAGES 2k Consortium 2017). This product will be followed up by a special issue of Climate of the Past, entitled “Climate of the past 2000 years: regional and trans-regional syntheses”. %0 journal article %@ 1616-7341 %A Staneva, J., Alari, V., Breivik, Oe., Bidlot, J.-R., Mogensen, K. %D 2017 %J Ocean Dynamics %N 1 %P 81-101 %R doi:10.1007/s10236-016-1009-0 %T Effects of wave-induced forcing on a circulation model of the North Sea %U https://doi.org/10.1007/s10236-016-1009-0 1 %X The effect of wind waves on water level and currents during two storms in the North Sea is investigated using a high-resolution Nucleus for European Modelling of the Ocean (NEMO) model forced with fluxes and fields from a high-resolution wave model. The additional terms accounting for wave-current interaction that are considered in this study are the Stokes-Coriolis force, the sea-state-dependent energy and momentum fluxes. The individual and collective role of these processes is quantified and the results are compared with a control run without wave effects as well as against current and water-level measurements from coastal stations. We find a better agreement with observations when the circulation model is forced by sea-state-dependent fluxes, especially in extreme events. The two extreme events, the storm Christian (25–27 October 2013), and about a month later, the storm Xaver (5–7 December 2013), induce different wave and surge conditions over the North Sea. Including the wave effects in the circulation model for the storm Xaver raises the modelled surge by more than 40 cm compared with the control run in the German Bight area. For the storm Christian, a difference of 20–30 cm in the surge level between the wave-forced and the stand-alone ocean model is found over the whole southern part of the North Sea. Moreover, the modelled vertical velocity profile fits the observations very well when the wave forcing is accounted for. The contribution of wave-induced forcing has been quantified indicating that this represents an important mechanism for improving water-level and current predictions. %0 journal article %@ 1616-7341 %A Stanev, E.V., Grashorn, S., Zhang, Y.J. %D 2017 %J Ocean Dynamics %N 8 %P 1003-1025 %R doi:10.1007/s10236-017-1071-2 %T Cascading ocean basins: numerical simulations of the circulation and interbasin exchange in the Azov-Black-Marmara-Mediterranean Seas system %U https://doi.org/10.1007/s10236-017-1071-2 8 %X In this paper, we use the unstructured grid model SCHISM to simulate the thermohydrodynamics in a chain of baroclinic, interconnected basins. The model shows a good skill in simulating the horizontal circulation and vertical profiles of temperature, salinity, and currents. The magnitude and phases of the seasonal changes of circulation are consistent with earlier observations. Among the mesoscale and subbasin-scale circulation features that are realistically simulated are the anticyclonic coastal eddies, the Sebastopol and Batumi eddies, the Marmara Sea outflow around the southern coast of the Limnos Island, and the pathway of the cold water originating from the shelf. The superiority of the simulations compared to earlier numerical studies is demonstrated with the example of model capabilities to resolve the strait dynamics, gravity currents originating from the straits, high-salinity bottom layer on the shallow shelf, as well as the multiple intrusions from the Bosporus Strait down to 700 m depth. The warm temperature intrusions from the strait produce the warm water mass in the intermediate layers of the Black Sea. One novel result is that the seasonal intensification of circulation affects the interbasin exchange, thus allowing us to formulate the concept of circulation-controlled interbasin exchange. To the best of our knowledge, the present numerical simulations, for the first time, suggest that the sea level in the interior part of the Black Sea can be lower than the sea level in the Marmara Sea and even in some parts of the Aegean Sea. The comparison with observations shows that the timings and magnitude of exchange flows are also realistically simulated, along with the blocking events. The short-term variability of the strait transports is largely controlled by the anomalies of wind. The simulations demonstrate the crucial role of the narrow and shallow strait of Bosporus in separating the two pairs of basins: Aegean-Marmara Seas from one side and Azov-Black Seas from the other side. The straits of Kerch and Dardanelles provide sufficient interbasin connectivity that prevents large phase lags of the sea levels in the neighboring basins. The two-layer flows in the three straits considered here show different dependencies upon the net transport, and the spatial variability of this dependence is also quite pronounced. We show that the blocking of the surface flow can occur at different net transports, thus casting doubt on a previous approach of using simple relationships to prescribe (steady) outflow and inflow. Specific attention is paid to the role of synoptic atmospheric forcing for the basin-wide circulation and redistribution of mass in the Black Sea. An important controlling process is the propagation of coastal waves. One major conclusion from this research is that modeling the individual basins separately could result in large inaccuracies because of the critical importance of the cascading character of these interconnected basins. %0 journal article %@ 1616-7341 %A Stanev, E.V., Grayek, S., Claustre, H., Schmechtig, C., Poteau, A. %D 2017 %J Ocean Dynamics %N 9 %P 1119-1136 %R doi:10.1007/s10236-017-1077-9 %T Water intrusions and particle signatures in the Black Sea: A Biogeochemical-Argo float investigation %U https://doi.org/10.1007/s10236-017-1077-9 9 %X Continuous observations during 3 years with a vertical resolution of 1 dbar from two Bio-Argo floats in the Black Sea that were equipped with oxygen optodes, chlorophyll fluorometers, and backscattering sensors are analyzed. The particle backscattering coefficient, b bp provides a proxy for the concentration of suspended particles. The observations clearly identify thermal and b bp intrusions down to ~700–800 m in the Bosporus inflow area. In this area, b bp is more than five times larger than elsewhere, which could indicate bacterial abundance and possible biological involvement in the precipitation of Mn-containing particles. The b bp anomalies become much shallower than the temperature anomalies with increasing distance to the east of the strait. Their maxima are located between the onset of the suboxic zone and the upper part of the anoxic layer. Unlike well-known intrusions that are caused by inflow, open ocean intrusions are shallower and often characterized by multiple layers of backscatter maxima with thicknesses of only 15–20 m. The ratio between backscattering coefficients measured at two wavelengths, which gives a proxy for particle size, shows that the relative amount of larger size particles in the anoxic layer increases with depth. The particle concentrations and their size distribution display different vertical variability, which indicates the complex transformation of biological matter. The lower concentration of particles and lower chlorophyll-a during the extremely warm 2016 reveals an overall positive correlation between the two properties. The trends in the particle backscattering coefficient in the suboxic zone during 2013–2016 could indirectly reveal a biogeochemical response to temperature changes. %0 journal article %@ 1353-3452 %A Bray, D., Storch, H.v. %D 2017 %J Science and Engineering Ethics %N 5 %P 1351-1367 %R doi:10.1007/s11948-014-9605-1 %T The Normative Orientations of Climate Scientists %U https://doi.org/10.1007/s11948-014-9605-1 5 %X In 1942 Robert K. Merton tried to demonstrate the structure of the normative system of science by specifying the norms that characterized it. The norms were assigned the abbreviation CUDOs: Communism, Universalism, Disinterestedness, and Organized skepticism. Using the results of an on-line survey of climate scientists concerning the norms of science, this paper explores the climate scientists’ subscription to these norms. The data suggests that while Merton’s CUDOs remain the overall guiding moral principles, they are not fully endorsed or present in the conduct of climate scientists: there is a tendency to withhold results until publication, there is the intention of maintaining property rights, there is external influence defining research and the tendency to assign the significance of authored work according to the status of the author rather than content of the paper. These are contrary to the norms of science as proposed by Robert K. Merton. %0 journal article %@ 0272-7714 %A Singer, A., Millat, G., Staneva, J., Kröncke, I. %D 2017 %J Estuarine, Coastal and Shelf Science %P 99-108 %R doi:10.1016/j.ecss.2017.02.003 %T Modelling benthic macrofauna and seagrass distribution patterns in a North Sea tidal basin in response to 2050 climatic and environmental scenarios %U https://doi.org/10.1016/j.ecss.2017.02.003 %X Small-scale spatial distribution patterns of seven macrofauna species, seagrass beds and mixed mussel/oyster reefs were modelled for the Jade Bay (North Sea, Germany) in response to climatic and environmental scenarios (representing 2050). For the species distribution models four presence-absence modelling methods were merged within the ensemble forecasting platform ‘biomod2’. The present spatial distribution (representing 2009) was modelled by statistically related species presences, true species absences and six high-resolution environmental grids. The future spatial distribution was then predicted in response to expected climate change-induced ongoing (1) sea-level rise and (2) water temperature increase. Between 2009 and 2050, the present and future prediction maps revealed a significant range gain for two macrofauna species (Macoma balthica, Tubificoides benedii), whereas the species' range sizes of five macrofauna species remained relatively stable across space and time. The predicted probability of occurrence (PO) of two macrofauna species (Cerastoderma edule, Scoloplos armiger) decreased significantly under the potential future habitat conditions. In addition, a clear seagrass bed extension (Zostera noltii) on the lower intertidal flats (mixed sediments) and a decrease in the PO of mixed Mytilus edulis/Crassostrea gigas reefs was predicted for 2050. Until the mid-21st century, our future climatic and environmental scenario revealed significant changes in the range sizes (gains-losses) and/or the PO (increases-decreases) for seven of the 10 modelled species at the study site. %0 journal article %@ 0899-8418 %D 2017 %J International Journal of Climatology %N 1 %P 169-179 %R doi:10.1002/joc.4695 %T Added value of high-resolution regional climate model: selected cases over the Bohai Sea and the Yellow Sea areas %U https://doi.org/10.1002/joc.4695 1 %X Added value (AV) from dynamical downscaling has long been a crucial and debatable issue in regional climate studies. To assess AV generated by COSMO Climate Local Model (CCLM), a model-reconstructed hindcast with 7 km grid resolution was compared against the forcing data set ERA-Interim (ERA-I) over the Bohai Sea and the Yellow Sea, with satellite and in situ observation as reference. Both quantitative metrics and qualitative assessments have been used in the investigation of AV by CCLM. Land surface winds, extreme winds, a typhoon, a cold surge and a vortex street have been selected in the assessment process. Statistical analysis on surface winds reveals that high-resolution CCLM hindcast can add value to ERA-I in reproducing wind intensities and direction, probability distribution and extreme winds mainly at mountain areas, which may be related to the highly resolved and accurate description of terrain roughness length and orographic barriers in CCLM. With respect to atmospheric processes, CCLM outperforms ERA-I in resolving detailed temporal and spatial structures for phenomena of a typhoon and of a cold surge; CCLM generates some orography-related phenomena such as a vortex street, which is not captured by ERA-I. These AVs demonstrate the utility of the 7-km resolution CCLM for regional and local climate studies and applications. %0 journal article %@ 2212-0947 %A Schwab, M., Meinke, I., Vanderlinden, J.-P., Storch, H.v. %D 2017 %J Weather and Climate Extremes %P 1-7 %R doi:10.1016/j.wace.2017.09.001 %T Regional decision-makers as potential users of Extreme Weather Event Attribution - Case studies from the German Baltic Sea coast and the Greater Paris area %U https://doi.org/10.1016/j.wace.2017.09.001 %X Extreme Event Attribution has raised increasing attention in climate science in the last years. It means to judge the extent to which certain weather-related extreme events have changed due to human influences on climate with probabilistic statements. Extreme Event Attribution is often anticipated to spur more than just scientific ambition. It is able to provide answers to a commonly asked questions after extreme events, namely, ‘can we blame it on climate change’ and is assumed to support decision-making of various actors engaged in climate change mitigation and adaptation. More in-depth research is widely lacking about who these actors are; in which context they can make use of it; and what requirements they have, to be able to actually apply Extreme Event Attribution. We have therefore addressed these questions with two empirical case studies looking at regional decision-makers who deal with storm surge risks in the German Baltic Sea region and heat waves in the Greater Paris area. Stakeholder interviews and workshops reveal that fields of application and requirements are diverse, difficult to explicitly identify, and often clearly associated with stakeholders' specific mandate, the hazard background, and the regional socio-economic setting. Among the considered stakeholders in the Baltic Sea region, Extreme Event Attribution is perceived to be most useful to awareness-raising, in particular for climate change mitigation. They emphasised the importance of receiving understandable information - and that, rather later, but with smaller uncertainties than faster, but with higher uncertainties. In the Paris case, we typically talked to people engaged in adaptation with expertise in terms of climate science, but narrowly defined mandates which is typical for the Paris-centred political system with highly specialised public experts. The interviewees claimed that Extreme Event Attribution is most useful to political leverage and public discourses. If novel information like this is not sorted out a priori, it needs to be clearly linked to impacts, preferably as monetary values lost. These examples underline the significance of conducting case-specific stakeholder mappings and consultation. Overall, our studies can thereby provide methods and exemplary empirical evidence to support developing useful services from Extreme Event Attribution for targeted groups of users. %0 journal article %@ 0304-3800 %A Taherzadeh, N., Kerimoglu, O., Wirtz, K. %D 2017 %J Ecological Modelling %P 279-289 %R doi:10.1016/j.ecolmodel.2017.07.008 %T Can we predict phytoplankton community size structure using size scalings of eco-physiological traits? %U https://doi.org/10.1016/j.ecolmodel.2017.07.008 %X Cell size is an important determining factor for predicting the physiological and ecological properties of phytoplankton. Size dependencies in eco-physiological properties are in general reported as log–log linear scaling relationships. Considerable uncertainty in these allometries, hence, limits our ability to link them to observed changes in phytoplankton community structures. In this study, we develop a size-based multi-species phytoplankton model and assess the sensitivity of the predicted community size structure to variations in allometric coefficients. The model describes the nutrient–phytoplankton–detritus dynamics within the upper mixed layer for a matrix of habitats, which are characterized by the deep layer nutrient concentration and mixing frequency. Predicted diatom community mean cell size becomes maximal at intermediate mixing frequencies, which confirms the importance of storage capacity (relative to the subsistence demand) at intermittent nutrient supplies. Smaller subsistence demand of large diatoms makes a critical factor in shaping the community size structure, while in environments with either short or long nutrient replenishment periods, maximum growth rate gains similar or more importance. Notably, in these environments, the diatom community converges towards unrealistically small species when we assumed a uniform (log–log linear) allometry in maximum growth rate. Independent theoretical and empirical arguments motivated the usage of non-uniform growth scaling, with which the minimal diatom cell size actually observed in nature is realized in long-term simulations. Using allometries parameterized for the entire phytoplankton community, the subsistence advantage of the larger species becomes insignificant, leading to a ubiquitous dominance of smaller species, even when assuming non-uniform scaling in maximum growth rate. This finding corresponds with the observed dominance of pico-phytoplankton in many parts of the ocean. All combinations of physiological allometries for diatom or mixed communities, however, underestimate both the mean cell size of the community and also size diversity. This may indicate a significant role of other ecological selection mechanisms, such as arising from size-selective grazing. The approach outlined in this paper helps to better assess the limits and the potential of size based phytoplankton models as an increasingly important tool in plankton research. %0 journal article %@ 2324-9676 %A Ohle, N., Schuster, D., Kappenberg, J., Sothmann, J., Rupolph, E. %D 2017 %J Journal of Applied Water Engineering and Research %N 2 %P 158-166 %R doi:10.1080/23249676.2016.1184596 %T Artificial sandbanks in the Elbe Estuary mouth: A method for surge mitigation? %U https://doi.org/10.1080/23249676.2016.1184596 2 %X Within the framework of different EU framework research projects (THESEUS and TIDE), investigations of the efficiency of artificial sandbanks in the mouth of the Elbe estuary for the mitigation of tidal energy and a better storm surge protection were carried out. The efficiency of the artificial sandbanks was analysed by means of two- and three-dimensional hydro- and morphodynamic models. The models calculate the water level and current velocities as well as the transport of dissolved constituents under mean and storm surge conditions. To allow the investigation of the effects of the artificial sandbanks on the water level and currents in the inner estuary, a high spatial grid resolution was used. Overall results of the investigations are presented and an outlook on how those measures can contribute to innovative risk mitigation is shown. %0 journal article %@ 0304-3800 %A Kerimoglu, O., Jacquet, S., Vinçon-Leite, B., Lemaire, B., Rimet, F., Soulignac, F., Trévisan, D., Anneville, O. %D 2017 %J Ecological Modelling %P 415-433 %R doi:10.1016/j.ecolmodel.2017.06.005 %T Modelling the plankton groups of the deep, peri-alpine Lake Bourget %U https://doi.org/10.1016/j.ecolmodel.2017.06.005 %X Predicting phytoplankton succession and variability in natural systems remains to be a grand challenge in aquatic ecosystems research. In this study, we identified six major plankton groups in Lake Bourget (France), based on cell size, taxonomic properties, food-web interactions and occurrence patterns: cyanobacterium Planktothrix rubescens, small and large phytoplankton, mixotrophs, herbivorous and carnivorous zooplankton. We then developed a deterministic dynamic model that describes the dynamics of these groups in terms of carbon and phosphorus fluxes, as well as of particulate organic phosphorus and dissolved inorganic phosphorus. The modular and generic model scheme, implemented as a set of modules under Framework for Aquatic Biogeochemical Models (FABM) enables run-time coupling of the plankton module an arbitrary number of times, each time with a prescribed position across the autotrophy/heterotrophy continuum. Parameters of the plankton groups were mainly determined conjointly by the taxonomic and allometric relationships, based on the species composition and average cellular volume of each group. The biogeochemical model was coupled to the one-dimensional General Ocean Turbulence Model (GOTM) and forced with local meteorological conditions. The coupled model system shows very high skill in predicting the spatiotemporal distributions of water temperature and dissolved inorganic phosphorus for five simulated years within the period 2004 to 2010, and intermediate skill in predicting the plankton succession. We performed a scenario analysis to gain insight into the factors driving the sudden disappearance of P. rubescens in 2010. Our results provide evidence for the hypothesis that the abundance of this species before the onset of stratification is critical for its success later in the growing season, pointing thereby to a priority effect. %0 journal article %@ 1616-7341 %A Jacob, B., Stanev, E.V. %D 2017 %J Ocean Dynamics %N 10 %P 1263-1281 %R doi:10.1007/s10236-017-1093-9 %T Interactions between wind and tidally induced currents in coastal and shelf basins %U https://doi.org/10.1007/s10236-017-1093-9 10 %X This paper addresses the impact of atmospheric variability on ocean circulation in tidal and non-tidal basins. The data are generated by an unstructured-grid numerical model resolving the dynamics in the coastal area, as well as in the straits connecting the North Sea and Baltic Sea. The model response to atmospheric forcing in different frequency intervals is quantified. The results demonstrate that the effects of the two mechanical drivers, tides and wind, are not additive, yet non-linear interactions play an important role. There is a tendency for tidally and wind-driven circulations to be coupled, in particular in the coastal areas and straits. High-frequency atmospheric variability tends to amplify the mean circulation and modify the exchange between the North and the Baltic Sea. The ocean response to different frequency ranges in the wind forcing is area-selective depending on specific local dynamics. The work done by wind on the oceanic circulation depends strongly upon whether the regional circulation is tidally or predominantly wind-driven. It has been demonstrated that the atmospheric variability affects the spring-neap variability very strongly. %0 journal article %@ 1758-678X %A Maraun, D., Shepherd, T.G., Widmann, M., Zappa, G., Walton, D., Gutierrez, J.M., Hagemann, S., Richter, I., Soares, P.M.M., Hall, A., Mearns, L.O. %D 2017 %J Nature Climate Change %P 764-773 %R doi:10.1038/nclimate3418 %T Towards process-informed bias correction of climate change simulations %U https://doi.org/10.1038/nclimate3418 %X Biases in climate model simulations introduce biases in subsequent impact simulations. Therefore, bias correction methods are operationally used to post-process regional climate projections. However, many problems have been identified, and some researchers question the very basis of the approach. Here we demonstrate that a typical cross-validation is unable to identify improper use of bias correction. Several examples show the limited ability of bias correction to correct and to downscale variability, and demonstrate that bias correction can cause implausible climate change signals. Bias correction cannot overcome major model errors, and naive application might result in ill-informed adaptation decisions. We conclude with a list of recommendations and suggestions for future research to reduce, post-process, and cope with climate model biases. %0 journal article %@ 2169-897X %A von Storch, H., Feser, F., Geyer, B., Klehmet, K., Li, D., Rockel, B., Schubert-Frisius, M., Tim, N., Zorita, E. %D 2017 %J Journal of Geophysical Research : Atmospheres %N 16 %P 8631-8649 %R doi:10.1002/2016JD026332 %T Regional reanalysis without local data: Exploiting the downscaling paradigm %U https://doi.org/10.1002/2016JD026332 16 %X This paper demonstrates two important aspects of regional dynamical downscaling of multidecadal atmospheric reanalysis. First, that in this way skillful regional descriptions of multidecadal climate variability may be constructed in regions with little or no local data. Second, that the concept of large‐scale constraining allows global downscaling, so that global reanalyses may be completed by additions of consistent detail in all regions of the world. Global reanalyses suffer from inhomogeneities. However, their large‐scale componenst are mostly homogeneous; Therefore, the concept of downscaling may be applied to homogeneously complement the large‐scale state of the reanalyses with regional detail—wherever the condition of homogeneity of the description of large scales is fulfilled. Technically, this can be done by dynamical downscaling using a regional or global climate model, which's large scales are constrained by spectral nudging. This approach has been developed and tested for the region of Europe, and a skillful representation of regional weather risks—in particular marine risks—was identified. We have run this system in regions with reduced or absent local data coverage, such as Central Siberia, the Bohai and Yellow Sea, Southwestern Africa, and the South Atlantic. Also, a global simulation was computed, which adds regional features to prescribed global dynamics. Our cases demonstrate that spatially detailed reconstructions of the climate state and its change in the recent three to six decades add useful supplementary information to existing observational data for midlatitude and subtropical regions of the world. %0 journal article %@ 2169-8961 %A Zhang, W., Wirtz, K. %D 2017 %J Journal of Geophysical Research : Biogeosciences %N 10 %P 2509-2526 %R doi:10.1002/2017JG003909 %T Mutual Dependence Between Sedimentary Organic Carbon and Infaunal Macrobenthos Resolved by Mechanistic Modeling %U https://doi.org/10.1002/2017JG003909 10 %X The mutual dependence between sedimentary total organic carbon (TOC) and infaunal macrobenthos is here quantified by a mechanistic model. The model describes (i) the vertical distribution of infaunal macrobenthic biomass resulting from a trade‐off between nutritional benefit (quantity and quality of TOC) and the costs of burial (respiration) and mortality, and (ii) the variable vertical distribution of TOC being in turn shaped by bioturbation of local macrobenthos. In contrast to conventional approaches, our model emphasizes variations of bioturbation both spatially and temporally depending on local food resources and macrobenthic biomass. Our implementation of the dynamic interaction between TOC and infaunal macrobenthos is able to capture a temporal benthic response to both depositional and erosional environments and provides improved estimates of the material exchange flux at the sediment‐water interface. Applications to literature data for the North Sea demonstrate the robustness and accuracy of the model and its potential as an analysis tool for the status of TOC and macrobenthos in marine sediments. Results indicate that the vertical distribution of infaunal biomass is shaped by both the quantity and the quality of OC, while the community structure is determined only by the quality of OC. Bioturbation intensity may differ by 1 order of magnitude over different seasons owing to variations in the OC input, resulting in a significant modulation on the distribution of OC. Our relatively simple implementation may further improve models of early diagenesis and marine food web dynamics by mechanistically connecting the vertical distribution of both TOC and macrobenthic biomass. %0 journal article %@ 2210-9838 %A Weisse, R., Weidemann, H. %D 2017 %J Procedia IUTAM %P 65-69 %R doi:10.1016/j.piutam.2017.09.010 %T Baltic Sea extreme sea levels 1948-2011: Contributions from atmospheric forcing %U https://doi.org/10.1016/j.piutam.2017.09.010 %X Extreme sea levels in the Baltic Sea are usually analyzed from tide-gauge data covering more or less extended periods. More comprehensive spatial or systematic analyses are less frequently available. Data from a high-resolution tide-surge model driven by high-resolution reanalyzed atmospheric fields reconstructing Baltic Sea sea levels from 1948 to 2011 on an hourly basis are analyzed. Meteorologically induced sea levels are characterized by pronounced annual to decadal fluctuations and a typical seasonal distribution comparable to the variability in regional wind climate. No substantial long-term trends over the considered period could be detected. Wind set-up represents the most dominant factor, however, short term variations in the filling levels of the basin and seiches contributed substantially to some of the observed peak water levels in the past. For the tide-gauge Wismar at the German Baltic Sea coast, it is exemplarily demonstrated that storm surges during periods with and without high filling levels occurred at about equal shares. When high filling levels were present, lower wind speeds were generally needed to sustain comparable peak water levels. Seiches also contributed to some of the observed extremes usually with a preferred phase shift. For Wismar, in about one third of the cases contribution from seiches at peak water level was found to exceed 10 cm. %0 journal article %@ 1866-3508 %A Groll, N., Weisse, R. %D 2017 %J Earth System Science Data %N 2 %P 955-968 %R doi:10.5194/essd-9-955-2017 %T A multi-decadal wind-wave hindcast for the North Sea 1949–2014: coastDat2 %U https://doi.org/10.5194/essd-9-955-2017 2 %X Long and consistent wave data are important for analysing wave climate variability and change. Moreover, such statistics are also needed in coastal and offshore design and for addressing safety-related issues at sea. Using the third-generation spectral wave model WAM a multi-decadal wind-wave hindcast for the North Sea covering the period 1949–2014 was produced. The hindcast is part of the coastDat database representing a consistent and homogenous met-ocean data set. It is shown that despite not being perfect, data from the wave hindcast are generally suitable for wave climate analysis. In particular comparisons of hindcast data with in situ and satellite observations show on average a reasonable agreement while a tendency towards overestimation of the highest waves could be inferred. Despite these limitations, the wave hindcast still provides useful data for assessing wave climate variability and change as well as for risk analysis, in particular when conservative estimates are needed. Hindcast data are stored at the World Data Center for Climate (WDCC) and can be freely accessed using the https://doi.org/10.1594/WDCC/coastDat-2_WAM-North_Sea (Groll and Weisse, 2016) or via the coastDat web-page http://www.coastdat.de. %0 journal article %@ 2190-4979 %A Bierstedt, S.E., Huenicke, B., Zorita, E., Ludwig, J. %D 2017 %J Earth System Dynamics %N 3 %P 639-652 %R doi:10.5194/esd-8-639-2017 %T A wind proxy based on migrating dunes at the Baltic coast: statistical analysis of the link between wind conditions and sand movement %U https://doi.org/10.5194/esd-8-639-2017 3 %X We include precipitation and temperature into our analysis, in addition to wind, to learn more about the dependency between these three atmospheric factors and their common influence on the dune system. We set up a statistical linear model based on the correlation between the frequency of days with specific wind conditions in a given season and dune migration velocities derived for that season. To some extent, the dune records can be seen as analogous to tree-ring width records, and hence we use a proxy validation method usually applied in dendrochronology, cross-validation with the leave-one-out method, when the observational record is short. The revealed correlations between the wind record from the reanalysis and the wind record derived from the dune structure is in the range between 0.28 and 0.63, yielding similar statistical validation skill as dendroclimatological records. %0 journal article %@ 2190-4979 %A Karabil, S., Zorita, E., Huenicke, B. %D 2017 %J Earth System Dynamics %N 4 %P 1031-1046 %R doi:10.5194/esd-8-1031-2017 %T Mechanisms of variability in decadal sea-level trends in the Baltic Sea over the 20th century %U https://doi.org/10.5194/esd-8-1031-2017 4 %X The investigation on the relation between the AMO-index and sea-level trends implies that this detected underlying factor is not connected to oceanic forcing driven from the North Atlantic region. %0 journal article %@ 0930-7575 %A Ho-Hagemann, H.T.M., Groeger, M., Rockel, B., Zahn, M., Geyer, B., Meier, H.E.M. %D 2017 %J Climate Dynamics %N 11-12 %P 3851-3876 %R doi:10.1007/s00382-017-3546-8 %T Effects of air-sea coupling over the North Sea and the Baltic Sea on simulated summer precipitation over Central Europe %U https://doi.org/10.1007/s00382-017-3546-8 11-12 %X This study introduces a new approach to investigate the potential effects of air-sea coupling on simulated precipitation inland over Central Europe. We present an inter-comparison of two regional climate models (RCMs), namely, the COSMO-CLM (hereafter CCLM) and RCA4 models, which are configured for the EURO-CORDEX domain in the coupled and atmosphere-only modes. Two versions of the CCLM model, namely, 4.8 and 5.0, join the inter-comparison being almost two different models while providing pronouncedly different summer precipitation simulations because of many changes in the dynamics and physics of CCLM in version 5.0. The coupling effect on the prominent summer dry bias over Central Europe is analysed using seasonal (JJA) mean statistics for the 30-year period from 1979 to 2009, with a focus on extreme precipitation under specific weather regimes. The weather regimes are compared between the coupled and uncoupled simulations to better understand the mechanism of the coupling effects. The comparisons of the coupled systems with the atmosphere-only models show that coupling clearly reduces the dry bias over Central Europe for CCLM 4.8, which has a large dry summer bias, but not for CCLM 5.0 and RCA4, which have smaller dry biases. This result implies that if the atmosphere-only model already yields reasonable summer precipitation over Central Europe, not much room for improvement exists that can be caused by the air-sea coupling over the North Sea and the Baltic Sea. However, if the atmosphere-only model shows a pronounced summer dry bias because of a lack of moisture transport from the seas into the region, the considered coupling may create an improved simulation of summer precipitation over Central Europe, such as for CCLM 4.8. For the latter, the benefit of coupling varies over the considered timescales. The precipitation simulations that are generated by the coupled system COSTRICE 4.8 and the atmosphere-only CCLM 4.8 are mostly identical for the summer mean. However, the COSTRICE simulations are generally more accurate than the atmosphere-only CCLM simulations if extreme precipitation is considered, particularly under Northerly Circulation conditions, in which the airflow from the North Atlantic Ocean passes the North Sea in the coupling domain. The air-sea feedback (e.g., wind, evaporation and sea surface temperature) and land-sea interactions are better reproduced with the COSTRICE model system than the atmosphere-only CCLM and lead to an improved simulation of large-scale moisture convergence from the sea to land and, consequently, increased heavy precipitation over Central Europe. %0 journal article %@ 1814-9324 %A Bierstedt, S.E., Huenicke, B., Zorita, E., Wagner, S., Gomez-Navarro, J.J. %D 2016 %J Climate of the Past %N 2 %P 317-338 %R doi:10.5194/cp-12-317-2016 %T Variability of daily winter wind speed distribution over Northern Europe during the past millennium in regional and global climate simulations %U https://doi.org/10.5194/cp-12-317-2016 2 %X We conclude that no clear systematic relationship between the mean temperature, the temperature gradient and/or the North Atlantic Oscillation, with the daily wind speed statistics can be inferred from these simulations. The understanding of past and future changes in the distribution of wind speeds, and thus of wind speed extremes, will require a detailed analysis of the representation of the interaction between large-scale and small-scale dynamics. %0 journal article %@ 1812-0784 %A Stanev, E.V., Schulz-Stellenfleth, J., Staneva, J., Grayek, S., Grashorn, S., Behrens, A., Koch, W., Pein, J. %D 2016 %J Ocean Science %N 5 %P 1105-1136 %R doi:10.5194/os-12-1105-2016 %T Ocean forecasting for the German Bight: from regional to coastal scales %U https://doi.org/10.5194/os-12-1105-2016 5 %X This paper describes recent developments based on advances in coastal ocean forecasting in the fields of numerical modeling, data assimilation, and observational array design, exemplified by the Coastal Observing System for the North and Arctic Seas (COSYNA). The region of interest is the North and Baltic seas, and most of the coastal examples are for the German Bight. Several pre-operational applications are presented to demonstrate the outcome of using the best available science in coastal ocean predictions. The applications address the nonlinear behavior of the coastal ocean, which for the studied region is manifested by the tidal distortion and generation of shallow-water tides. Led by the motivation to maximize the benefits of the observations, this study focuses on the integration of observations and modeling using advanced statistical methods. Coastal and regional ocean forecasting systems do not operate in isolation but are linked, either weakly by using forcing data or interactively using two-way nesting or unstructured-grid models. Therefore, the problems of downscaling and upscaling are addressed, along with a discussion of the potential influence of the information from coastal observatories or coastal forecasting systems on the regional models. One example of coupling coarse-resolution regional models with a fine-resolution model interface in the area of straits connecting the North and Baltic seas using a two-way nesting method is presented. Illustrations from the assimilation of remote sensing, in situ and high-frequency (HF) radar data, the prediction of wind waves and storm surges, and possible applications to search and rescue operations are also presented. Concepts for seamless approaches to link coastal and regional forecasting systems are exemplified by the application of an unstructured-grid model for the Ems Estuary. %0 journal article %@ 0079-6611 %A Holt, J., Schrum, C., Cannaby, H., Daewel, U., Allen, I., Artioli, Y., Bopp, L., Butenschon, M., Fach, B.A., Harle, J., Pushpadas, D., Salihoglu, B., Wakelin, S. %D 2016 %J Progress in Oceanography %P 91-115 %R doi:10.1016/j.pocean.2015.11.004 %T Potential impacts of climate change on the primary production of regional seas: A comparative analysis of five European seas %U https://doi.org/10.1016/j.pocean.2015.11.004 %X Comparing projections for the end of the 21st century with mean present day conditions, these simulations generally show an increase in seasonal and permanent stratification (where present). However, the first order (low- and mid-latitude) effect in the open ocean projections of increased permanent stratification leading to reduced nutrient levels, and so to reduced primary production, is largely absent, except in the NE Atlantic. Even in the two highly stratified, deep water seas we consider (Black and Baltic Seas) the increase in stratification is not seen as a first order control on primary production. Instead, results show a highly heterogeneous picture of positive and negative change arising from complex combinations of multiple physical drivers, including changes in mixing, circulation and temperature, which act both locally and non-locally through advection. %0 journal article %@ 1726-4170 %A Maerz, J., Hofmeister, R., Lee, E.M.van der, Graewe, U., Riethmueller, R., Wirtz, K.W. %D 2016 %J Biogeosciences %N 17 %P 4863-4876 %R doi:10.5194/bg-13-4863-2016 %T Maximum sinking velocities of suspended particulate matter in a coastal transition zone %U https://doi.org/10.5194/bg-13-4863-2016 17 %X Marine coastal ecosystem functioning is crucially linked to the transport and fate of suspended particulate matter (SPM). Transport of SPM is controlled by, amongst other factors, sinking velocity ws. Since the ws of cohesive SPM aggregates varies significantly with size and composition of the mineral and organic origin, ws exhibits large spatial variability along gradients of turbulence, SPM concentration (SPMC) and SPM composition. In this study, we retrieved ws for the German Bight, North Sea, by combining measured vertical turbidity profiles with simulation results for turbulent eddy diffusivity. We analyzed ws with respect to modeled prevailing dissipation rates ϵ and found that mean ws were significantly enhanced around log10(ϵ (m2 s−3)) ≈ −5.5. This ϵ region is typically found at water depths of approximately 15 to 20 m along cross-shore transects. Across this zone, SPMC declines towards the offshore waters and a change in particle composition occurs. This characterizes a transition zone with potentially enhanced vertical fluxes. Our findings contribute to the conceptual understanding of nutrient cycling in the coastal region which is as follows. Previous studies identified an estuarine circulation. Its residual landward-oriented bottom currents are loaded with SPM, particularly within the transition zone. This retains and traps fine sediments and particulate-bound nutrients in coastal waters where organic components of SPM become remineralized. Residual surface currents transport dissolved nutrients offshore, where they are again consumed by phytoplankton. Algae excrete extracellular polymeric substances which are known to mediate mineral aggregation and thus sedimentation. This probably takes place particularly in the transition zone and completes the coastal nutrient cycle. The efficiency of the transition zone for retention is thus suggested as an important mechanism that underlies the often observed nutrient gradients towards the coast. %0 journal article %@ 0277-3791 %A Xoplaki, E., Fleitmann, D., Luterbacher, J., Wagner, S., Haldon, J.F., Zorita, E., Telelis, I., Toreti, A., Izdebski, A. %D 2016 %J Quaternary Science Reviews %P 229-252 %R doi:10.1016/j.quascirev.2015.10.004 %T The Medieval Climate Anomaly and Byzantium: A review of the evidence on climatic fluctuations, economic performance and societal change %U https://doi.org/10.1016/j.quascirev.2015.10.004 %X Our interdisciplinary analysis is based on all available sources of information on the climate and society of Byzantium, that is textual (documentary), archaeological, environmental, climate and climate model-based evidence about the nature and extent of climate variability in the eastern Mediterranean. The key challenge was, therefore, to assess the relative influence to be ascribed to climate variability and change on the one hand, and on the other to the anthropogenic factors in the evolution of Byzantine state and society (such as invasions, changes in international or regional market demand and patterns of production and consumption, etc.). The focus of this interdisciplinary study was to address the possible causal relationships between climatic and socio-economic change and to assess the resilience of the Byzantine socio-economic system in the context of climate change impacts. %0 journal article %@ 0930-7575 %A Xia, L., Storch, H.v., Feser, F., Wu, J. %D 2016 %J Climate Dynamics %N 7 %P 2121-2138 %R doi:10.1007/s00382-015-2954-x %T A study of quasi-millennial extratropical winter cyclone activity over the Southern Hemisphere %U https://doi.org/10.1007/s00382-015-2954-x 7 %X The winter extratropical cyclone activity in the Southern Hemisphere during the last one thousand years within a global climate simulation was analyzed by tracking cyclones, and then clustering them into ten clusters consecutively for each hundred years. There is very strong year-to-year variability for Southern Hemispheric winter extratropical cyclone numbers and larger variations on centennial time scale, more so than for its Northern Hemispherical counterparts. However, no obvious trend can be found. The mean tracks of clusters over the Southern Indian Ocean and near New Zealand shift poleward from the eleventh to the twentieth century while the clusters in the central Southern Pacific shift equatorward. Storm track clusters with largest deepening rates are found over the Southwestern Indian Ocean. In the twentieth century, rapidly deepening cyclones appear more often while long lifespan cyclones appear less frequently. The winter storm activity in the Southern Hemisphere is closely related to the Antarctic Oscillation. The cyclone frequency over the Indian Ocean and South Pacific Ocean can be associated with the Indian Ocean Dipole and El Nino-Southern Oscillation respectively. %0 journal article %@ 0930-7575 %A Tim, N., Bravo de Guenni, L. %D 2016 %J Climate Dynamics %N 1 %P 211-234 %R doi:10.1007/s00382-015-2832-6 %T Oceanic influence on the precipitation in Venezuela under current and future climate %U https://doi.org/10.1007/s00382-015-2832-6 1 %X The Pacific and Atlantic oceanic influences on observational rainfall data from weather stations over Venezuela are analyzed using Canonical Correlation Analysis (CCA) executed in the Climate Predictability Tool. CCA is further conducted on rainfall and sea surface temperature data obtained from the Max Planck Institute for Meteorology Earth System Model (MPI-ESM) for historical (1951–2010) and future (2041–2100) periods. Four oceanic regions (North Tropical Atlantic, Niño3, Niño3.4 and an area which includes all previous three) are used for the CCA using data from the Extended Reconstructed Sea Surface Temperature (ERSST) data set, while precipitation data from two regions: a coastal region and an inland region are used in the analysis. Venezuelan seasons (dry and wet) were separated into an early and a late period. The oceanic impact on the precipitation of the station data is, in the majority of the cases, higher in the inland than at the coast. The Pacific’s influence is stronger in the early dry season than in the wet season, whereas the Atlantic’s influence is stronger in the wet season (inland). In contrast, CCA applied to the model data provides highest correlation coefficients in the late wet season for all oceanic regions. In most cases the North Tropical Atlantic has a stronger influence than the Niño regions. %0 journal article %@ 0026-1165 %A Li, D., Storch, H.v., Geyer, B. %D 2016 %J Journal of the Meteorological Society of Japan %P 47-68 %R doi:10.2151/jmsj.2015-044 %T Testing Reanalyses in Constraining Dynamical Downscaling %U https://doi.org/10.2151/jmsj.2015-044 %X  The downscaling simulations driven by ERAint, JRA55, and CFSR are consistent with each other in the reproduction of local wind speed and direction; the simulations driven by ERAint and JRA55 are slightly better for strong winds and those driven by CFSR are better for light winds. All three simulations generate local wind estimates that are superior to those of the simulation driven by CCLM_55km. This superiority reflects the better quality of the CFSR, ERAint, and JRA55 reanalyses with regard to assimilated local observations compared with the CCLM_55km hindcast, which exploits only upper-air large scale NCEP1 wind fields. %0 journal article %@ 2169-9275 %A Ocana, V., Zorita, E., Heimbach, P. %D 2016 %J Journal of Geophysical Research : Oceans %N 4 %P 2183-2202 %R doi:10.1002/2015JC011301 %T Stochastic secular trends in sea level rise %U https://doi.org/10.1002/2015JC011301 4 %X Global mean sea level (GMSL) has been rising since (at least) the 19th century and the rate of rise may be increasing. Several studies that attempt to explain the long term trend of GMSL during the instrumental record share the common assumption that this trend is deterministic in nature and different from natural variations. Here we show that the trend can alternatively be explained, at least in part, as being caused by random variations within the coupled ocean-atmosphere-cryosphere system, and hence not having a deterministic origin. These random trends, which add to externally forced changes (e.g. through anthropogenic climate change), are a consequence of the integrated character of GMSL, which is the cumulative addition of temporal contributions that exhibit random character, and whose integration results in GMSL variations with persistence on decadal-centennial time scales. The generation of trends by integration of random stationary noise (i.e. even in a constant climate) is a robust and fundamental feature of stochastically forced systems with memory. The integrated character of GMSL results in an intrinsic difficulty in distinguishing internal from externally forced trends. This article is protected by copyright. %0 journal article %@ 0026-1165 %A Li, D., Storch, H.v., Geyer, B. %D 2016 %J Journal of the Meteorological Society of Japan %P 47-68 %R doi:10.2151/jmsj.2015-044 %T Testing Reanalyses in Constraining Dynamical Downscaling %U https://doi.org/10.2151/jmsj.2015-044 %X  The downscaling simulations driven by ERAint, JRA55, and CFSR are consistent with each other in the reproduction of local wind speed and direction; the simulations driven by ERAint and JRA55 are slightly better for strong winds and those driven by CFSR are better for light winds. All three simulations generate local wind estimates that are superior to those of the simulation driven by CCLM_55km. This superiority reflects the better quality of the CFSR, ERAint, and JRA55 reanalyses with regard to assimilated local observations compared with the CCLM_55km hindcast, which exploits only upper-air large scale NCEP1 wind fields. %0 journal article %@ 2169-897X %A Li, D., Storch, H.v., Geyer, B. %D 2016 %J Journal of Geophysical Research : Atmospheres %N 1 %P 111-129 %R doi:10.1002/2015JD024177 %T High-resolution wind hindcast over the Bohai Sea and the Yellow Sea in East Asia: Evaluation and wind climatology analysis %U https://doi.org/10.1002/2015JD024177 1 %X A 34 year (1979–2012) high-resolution (7 km grid) atmospheric hindcast over the Bohai Sea and the Yellow Sea (BYS) has been performed using COSMO-CLM (CCLM) forced by ERA-Interim reanalysis data (ERA-I). The accuracy of CCLM in surface wind reproduction and the added value of dynamical downscaling to ERA-I have been investigated through comparisons with the QuikSCAT Level2B 12.5 km version 3 (L2B12v3) swath data and in situ observations. The results revealed that CCLM has a reliable ability to reproduce the regional wind characteristics over the BYS. Added value to ERA-I has been detected in the coastal areas with complex orography. CCLM wind quality had strong seasonal variability, with better performance in the summer relative to ERA-I, even in the offshore areas. CCLM was better able to represent light and moderate winds but had even more added value for strong winds relative to ERA-I. The spatial digital filter method was used to investigate the scale of the added value, and the results show that CCLM adds value to ERA-I mainly in medium scales of wind variability. Furthermore, wind climatology was investigated, and significant increasing trends in the south Yellow Sea especially in winter and spring were found for seasonal mean wind speeds. %0 journal article %@ 1812-0784 %A Tim, N., Zorita, E., Huenicke, B., Yi, X., Emeis, K.-C. %D 2016 %J Ocean Science %N 3 %P 807-823 %R doi:10.5194/os-12-807-2016 %T The importance of external climate forcing for the variability and trends of coastal upwelling in past and future climate %U https://doi.org/10.5194/os-12-807-2016 3 %X The eastern boundary upwelling systems, located in the subtropics at the eastern boundary of the Atlantic and Pacific oceans and mainly driven by the trade winds, are the major coastal upwelling regions. Previous studies have suggested that the intensity of upwelling in these areas in the past centuries may have been influenced by the external radiative forcing, for instance by changes in solar irradiance, and it will also be influenced in the future by the increasing atmospheric greenhouse gases. Here, we analyse the impact of the external climate forcing on these upwelling systems in ensembles of simulations of two Earth system models. The ensembles contain three simulations for each period covering the past millennium (900–1849) and the 20th century (1850–2005). One of these Earth system models additionally includes the near future (2006–2100). Using a set of simulations, differing only in their initial conditions, enables us to test whether the observed variability and trends are driven by the external radiative forcing. Our analysis shows that the variability of the simulated upwelling is largely not affected by the external forcing and that, generally, there are no significant trends in the periods covering the past and future. Only in future simulations with the strongest increase of greenhouse gas concentrations the upwelling trends are significant and appear in all members of the ensemble. %0 journal article %@ 1752-0894 %A Gagen, M.H., Zorita, E., McCarroll, D., zahn, M., Young, G.H.F., Robertson, I. %D 2016 %J Nature Geoscience %P 630-635 %R doi:10.1038/ngeo2752 %T North Atlantic summer storm tracks over Europe dominated by internal variability over the past millennium %U https://doi.org/10.1038/ngeo2752 %X Certain large, sustained anomalies in European temperatures in the past millennium are probably the result of internal variation. Such internal variations can modulate regional temperatures away from the expected response to greenhouse gas forcing. Here we assess the causes of European summer temperature variability over the past millennium using temperature observations, simulations and reconstructions. We find multidecadal-mean summer temperatures have varied within a span of 1 K, largely controlled by external forcing. By contrast, we find subcontinental variations, described by the temperature contrast between northern and southern Europe (the meridional temperature gradient), vary with a span of 2 K, and are controlled by internal processes. These variations are the result of redistributions of precipitation and cloud cover linked to oscillations in the position of the summer storm track. In contrast to recent twentieth-century winter-time trends, variations of the summer storm track over the past millennium show a weak response to external forcing, and instead are dominated by stochastic internal variability. We argue that the response of European summer temperatures to anthropogenic greenhouse forcing is likely to be spatially modulated by the same stochastic internal processes that have caused periods of cool, wet summers in northern Europe over the last millennium. %0 journal article %@ 1616-7341 %A Feng, J., Storch, H.v., Weisse, R., Jiang, W. %D 2016 %J Ocean Dynamics %N 10 %P 1301-1315 %R doi:10.1007/s10236-016-0986-3 %T Changes of storm surges in the Bohai Sea derived from a numerical model simulation, 1961–2006 %U https://doi.org/10.1007/s10236-016-0986-3 10 %X Using the tide-surge circulation model ADCIRC, the storm surges in the Bohai Sea were hindcasted from 1961 to 2006 after a regional model-based reconstruction of wind conditions. Through comparison with four storm surge cases that happened in the Bohai Sea and long-time observations at four tide gauges in the Yellow Sea, it is concluded that the model is capable of reproducing the conditions of storm surges in the past few decades in this area. The spatial distribution, the seasonal variation, the interdecadal variability, and the long-time trend were analyzed using the model results. Results show that the storm surges in the three bays of the Bohai Sea are more serious than those in other areas. The storm surges exhibit obvious seasonal variations—they are more serious in spring and autumn. Obvious interdecadal variations and long-time decreasing trends take place in the Bohai Sea. Storm surge indices show statistically significant negative correlations to the Arctic Oscillation (AO) and a statistically significant positive correlation to the Siberian High (SH). Linear regression analysis was used to determine a robust link between the indices of the storm surges and the AO and SH. Using this link, conditions of the storm surges from 1900 to 2006 were estimated from the long-time AO and SH. %0 journal article %@ 1616-7341 %A Alari, V., Staneva, J., Breivik, O., Bidlot, J.-R., Mogensen, K., Janssen, P. %D 2016 %J Ocean Dynamics %N 8 %P 917-930 %R doi:10.1007/s10236-016-0963-x %T Surface wave effects on water temperature in the Baltic Sea: simulations with the coupled NEMO-WAM model %U https://doi.org/10.1007/s10236-016-0963-x 8 %X Coupled circulation (NEMO) and wave model (WAM) system was used to study the effects of surface ocean waves on water temperature distribution and heat exchange at regional scale (the Baltic Sea). Four scenarios—including Stokes-Coriolis force, sea-state dependent energy flux (additional turbulent kinetic energy due to breaking waves), sea-state dependent momentum flux and the combination these forcings—were simulated to test the impact of different terms on simulated temperature distribution. The scenario simulations were compared to a control simulation, which included a constant wave-breaking coefficient, but otherwise was without any wave effects. The results indicate a pronounced effect of waves on surface temperature, on the distribution of vertical temperature and on upwelling’s. Overall, when all three wave effects were accounted for, did the estimates of temperature improve compared to control simulation. During the summer, the wave-induced water temperature changes were up to 1 °C. In northern parts of the Baltic Sea, a warming of the surface layer occurs in the wave included simulations in summer months. This in turn reduces the cold bias between simulated and measured data, e.g. the control simulation was too cold compared to measurements. The warming is related to sea-state dependent energy flux. This implies that a spatio-temporally varying wave-breaking coefficient is necessary, because it depends on actual sea state. Wave-induced cooling is mostly observed in near-coastal areas and is the result of intensified upwelling in the scenario, when Stokes-Coriolis forcing is accounted for. Accounting for sea-state dependent momentum flux results in modified heat exchange at the water-air boundary which consequently leads to warming of surface water compared to control simulation. %0 journal article %@ 0171-8630 %A Singer, A., Schueckel, U., Beck, M., Bleich, O., Brumsack, H.-J., Freund, H., Geimecke, C., Lettmann, K.A., Millat, G., Staneva, J., Vanselow, A., Westphal, H., Wolff, J.-O., Wurpts, A., Kroencke, I. %D 2016 %J Marine Ecology - Progress Series %P 13-30 %R doi:10.3354/meps11756 %T Small-scale benthos distribution modelling in a North Sea tidal basin in response to climatic and environmental changes (1970s-2009) %U https://doi.org/10.3354/meps11756 %X We used small-scale species distribution models to predict the past and present spatial distribution of 7 characteristic macrofauna species in response to climatic and environmental changes that have been recorded for the Jade Bay (German Wadden Sea) over the last 4 decades (1970s to 2009). Four presence-absence modelling algorithms (RF, MARS, GLM, GBM) were merged within the ensemble forecasting platform ‘biomod2’. The present spatial distribution (representing 2009) was modelled based on statistical relationships between species presences, true species absences and 7 high-resolution (5 m) environmental grids. The past spatial distribution (representing the 1970s) was then hindcast in response to climate change-induced (1) sea-level rise, (2) water temperature increase and (3) seagrass recovery due to de-eutrophication. The past distribution scenario was evaluated using independent historical macrofauna data from the 1970s. Present ensemble prediction maps accurately captured the potential ecological niches of the modelled species throughout Jade Bay (i.e. good to excellent true skill statistic [TSS] and area under the receiver operating characteristic curve [AUC] evaluation measures). The predicted present macrofauna distribution correlated most significantly with hydrodynamic conditions (submergence time, shear stress) and sediment characteristics (mud content). The past distribution scenario revealed significant changes in small-scale spatial distribution patterns of the characteristic modelled species (1970s to 2009) and showed a very good match with historical macrofauna data. Climate change-induced sea-level rise and its local implications for Jade Bay (changes in topography, tidal range and submergence time), and water temperature increase explained the potential macrofauna distribution shifts over the last 4 decades. %0 journal article %@ 2325-1026 %A Bieser, J., Schrum, C. %D 2016 %J Elementa: Science of the Anthropocene %P 111 %R doi:10.12952/journal.elementa.000111 %T Impact of marine mercury cycling on coastal atmospheric mercury concentrations in the North- and Baltic Sea region %U https://doi.org/10.12952/journal.elementa.000111 %X The mercury flux from the ocean influenced coastal atmospheric mercury concentrations. Running CMAQ coupled with the ocean model lead to better agreement with GEM observations. Directly at the coast GEM concentrations could be increased by up to 10% on annual average and observed peaks could be reproduced much better. At stations 100km downwind the impact was still observable but reduced to 1–3%. %0 journal article %@ 0306-2619 %A Li, D., Geyer, B., Bisling, P. %D 2016 %J Applied Energy %P 575-589 %R doi:10.1016/j.apenergy.2016.07.010 %T A model-based climatology analysis of wind power resources at 100-m height over the Bohai Sea and the Yellow Sea %U https://doi.org/10.1016/j.apenergy.2016.07.010 %X China has set ambitious goals for the development of offshore wind energy to meet the increasing energy demand of coastal provinces. Many studies have assessed the potential offshore wind energy in Chinese territorial waters. However, few studies have focused on the climatology, variability, and extreme climate of wind speeds and wind power, especially at hub height in this area. This type of study is important for selecting promising sites for offshore wind farms. In the present study, a 35-year (1979–2013) high-resolution (7 km) wind hindcast over the Bohai Sea and the Yellow Sea (BYS) at 100-m height was constructed using the regional climate model COSMO-CLM (CCLM) driven by the ERA-Interim reanalysis dataset. The quality of wind speeds reconstructed by CCLM was assessed by a comparison with observation data at several stations. After verification, the climatology, variability, and extreme climate of winds over the BYS were spatially and temporally investigated. The results show that the 35-year mean wind speed is mostly between 7.0 and 7.5 m/s; in the coastal areas of the BYS, the mean is less than 7.0 m/s, and in the remote offshore areas, the mean is greater than 7.5 m/s. The daily mean wind speed is stronger (weaker) in winter (summer) half year, with stronger (weaker) spatial variability. Wind power density is mainly 300–500 W/m2. The interannual variability of annual mean wind speed and the wind power are in the range of 0.1–0.3 m/s and 10–40 W/m2, respectively. Decadal variances of the mean wind speed and the wind power are roughly within ±2% and ±5%, respectively, with a stronger variability along the southwestern coasts of the Yellow Sea. The distribution patterns of extreme winds (i.e., 5, 10, 30, and 50-year return values) are generally similar, with strength increasing from the northwest to the southeast. The wind energy characteristics for water areas and potential wind farm sites are summarized. %0 journal article %@ 1812-0784 %A Staneva, J., Wahle, K., Guenther, H., Stanev, E. %D 2016 %J Ocean Science %N 3 %P 797-806 %R doi:10.5194/os-12-797-2016 %T Coupling of wave and circulation models in coastal–ocean predicting systems: a case study for the German Bight %U https://doi.org/10.5194/os-12-797-2016 3 %X This study addresses the impact of coupling between wave and circulation models on the quality of coastal ocean predicting systems. This is exemplified for the German Bight and its coastal area known as the Wadden Sea. The latter is the area between the barrier islands and the coast. This topic reflects the increased interest in operational oceanography to reduce prediction errors of state estimates at coastal scales, which in many cases are due to unresolved non-linear feedback between strong currents and wind waves. In this study we present analysis of wave and hydrographic observations, as well as results of numerical simulations. A nested-grid modelling system is used to produce reliable nowcasts and short-term forecasts of ocean state variables, including waves and hydrodynamics. The database includes ADCP observations and continuous measurements from data stations. The individual and combined effects of wind, waves and tidal forcing are quantified. The performance of the forecast system is illustrated for the cases of several extreme events. The combined role of wave effects on coastal circulation and sea level are investigated by considering the wave-dependent stress and wave breaking parameterization. Also the response, which the circulation exerts on the waves, is tested for the coastal areas. The improved skill of the coupled forecasts compared to the non-coupled ones, in particular during extreme events, justifies the further enhancements of coastal operational systems by including wave effects in circulation models. %0 journal article %@ 2169-897X %A Barkhordarian, A., Storch, H.v., Zorita, E., Gomez-Navarro, J.J. %D 2016 %J Journal of Geophysical Research : Atmospheres %N 22 %P 13207-13217 %R doi:10.1002/2015JD024648 %T An attempt to deconstruct recent climate change in the Baltic Sea Basin %U https://doi.org/10.1002/2015JD024648 22 %X Results indicate that, over the past decades, the climate in the Baltic Sea Basin has undergone a change that is beyond the estimated range of natural variability. We test the hypothesis that this change may be understood as a manifestation of global warming due to increasing concentrations of greenhouse gases (GHGs). We find that changes in near-surface temperature support our hypothesis that the effect of GHG is needed to simulate the observed changes. The pattern correlation and regression results clearly illustrate the concerted emergence of an anthropogenic signal consistent with the GHG signal in summer and autumn in the 21st century. However, none of the 19 regional climate simulations used in this study reproduce the observed warming. The observed trends in precipitation and surface solar radiation are also partially inconsistent with the expected changes due to GHG forcing. We conclude that, besides the regional response to GHG forcing, other human-made drivers have had an imprint. Regional emission of industrial aerosols has been strongly reduced in this region, and we suggest that this reduction may be the missing driver. %0 journal article %@ 0034-6853 %A Ruddiman, W.F., Fuller, D.Q., Kutzbach, J.E., Tzedakis, P.C., Kaplan, J.O., Ellis, E.C., Vavrus, S.J., Roberts, C.N., Fyfe, R., He, F., Lemmen, C., Woodbridge, J %D 2016 %J Reviews of Geophysics %N 1 %P 93-118 %R doi:10.1002/2015RG000503 %T Late Holocene climate: Natural or anthropogenic? %U https://doi.org/10.1002/2015RG000503 1 %X For more than a decade, scientists have argued about the warmth of the current interglaciation. Was the warmth of the preindustrial late Holocene natural in origin, the result of orbital changes that had not yet driven the system into a new glacial state? Or was it in considerable degree the result of humans intervening in the climate system through greenhouse gas emissions from early agriculture? Here we summarize new evidence that moves this debate forward by testing both hypotheses. By comparing late Holocene responses to those that occurred during previous interglaciations (in section 2), we assess whether the late Holocene responses look different (and thus anthropogenic) or similar (and thus natural). This comparison reveals anomalous (anthropogenic) signals. In section 3, we review paleoecological and archaeological syntheses that provide ground truth evidence on early anthropogenic releases of greenhouse gases. The available data document large early anthropogenic emissions consistent with the anthropogenic ice core anomalies, but more information is needed to constrain their size. A final section compares natural and anthropogenic interpretations of the δ13C trend in ice core CO2. %0 journal article %@ 1561-8633 %A Staneva, J., Wahle, K., Koch, W., Behrens, A., Fenoglio-Marc, L., Stanev, E.V. %D 2016 %J Natural Hazards and Earth System Sciences %N 11 %P 2373-2389 %R doi:10.5194/nhess-16-2373-2016 %T Coastal flooding: impact of waves on storm surge during extremes. A case study for the German Bight %U https://doi.org/10.5194/nhess-16-2373-2016 11 %X This study addresses impact of wind, waves, tidal forcing and baroclinicity on the sea level of the German Bight during extremes. The role of waves-induced processes, tides and baroclinicity is quantified and the results are compared with observational data that include various in-situ measurements as well as satellite data. A coupled, high-resolution, model system is used to simulate the wind waves, water level and three-dimensional hydrodynamics. The effects of the wind waves on sea level variability are studied accounting for wave-dependent stress, wave-breaking parameterization and wave-induced effects on vertical mixing. The analyses of the coupled model results reveal a closer match with observations than for the stand-alone circulation model, especially during the extreme storm Xaver in December 2013. The predicted surge of the coupled model enhances significantly during extremes when considering wave-current interaction processes. The wave-dependent approach yields to a contribution of more than 30 % in some coastal area during extremes. The improved skill resulting from the new developments justifies further use of coupled wave and three dimensional circulation models for improvement of coastal flooding predictions. %0 journal article %@ 1748-9326 %A Luterbacher, J., Werner, J.P., Smerdon, J.E., Fernandez-Donado, L., Gonzalez-Rouco, F.J., Barriopedro, D., Ljungqvist, F.C., Buentgen, U., Zorita, E., Wagner, S., Esper, J., McCarroll, D., Toreti, A., Frank, D., Jungclaus, J.H., Barriendos, M., Bertolin, C., Bothe, O., Brazdil, R., Camuffo, D., Cobrovolny, P., Gagen, M., Garcia-Bustamante, E., Ge, Q., Gomez-Navarro, J.J., Guiot, J., Hao, Z., Hegerl, G.C., Holmgren, K.Klimenko, V.V., Martin-Chivelet, J., Pfister, C., Roberts, N., Schindler, A., Schurer, A., Solomina, O., Gunten, L.v., Wahl, E., Wanner, H., Wetter, O., Xoplaki, E., Yuan, N., Zanchettin, D., Zhang, H., Zerefos, C. %D 2016 %J Environmental Research Letters %N 2 %P 024001 %R doi:10.1088/1748-9326/11/2/024001 %T European summer temperatures since Roman times %U https://doi.org/10.1088/1748-9326/11/2/024001 2 %X The spatial context is critical when assessing present-day climate anomalies, attributing them to potential forcings and making statements regarding their frequency and severity in a long-term perspective. Recent international initiatives have expanded the number of high-quality proxy-records and developed new statistical reconstruction methods. These advances allow more rigorous regional past temperature reconstructions and, in turn, the possibility of evaluating climate models on policy-relevant, spatio-temporal scales. Here we provide a new proxy-based, annually-resolved, spatial reconstruction of the European summer (June–August) temperature fields back to 755 CE based on Bayesian hierarchical modelling (BHM), together with estimates of the European mean temperature variation since 138 BCE based on BHM and composite-plus-scaling (CPS). Our reconstructions compare well with independent instrumental and proxy-based temperature estimates, but suggest a larger amplitude in summer temperature variability than previously reported. Both CPS and BHM reconstructions indicate that the mean 20th century European summer temperature was not significantly different from some earlier centuries, including the 1st, 2nd, 8th and 10th centuries CE. The 1st century (in BHM also the 10th century) may even have been slightly warmer than the 20th century, but the difference is not statistically significant. Comparing each 50 yr period with the 1951–2000 period reveals a similar pattern. Recent summers, however, have been unusually warm in the context of the last two millennia and there are no 30 yr periods in either reconstruction that exceed the mean average European summer temperature of the last 3 decades (1986–2015 CE). A comparison with an ensemble of climate model simulations suggests that the reconstructed European summer temperature variability over the period 850–2000 CE reflects changes in both internal variability and external forcing on multi-decadal time-scales. For pan-European temperatures we find slightly better agreement between the reconstruction and the model simulations with high-end estimates for total solar irradiance. Temperature differences between the medieval period, the recent period and the Little Ice Age are larger in the reconstructions than the simulations. This may indicate inflated variability of the reconstructions, a lack of sensitivity and processes to changes in external forcing on the simulated European climate and/or an underestimation of internal variability on centennial and longer time scales. %0 journal article %@ 0013-9998 %A de Guttry, C., Doering, M., Ratter, B. %D 2016 %J Die Erde - Journal of the Geographical Society of Berlin %N 2 %P 109-118 %R doi:10.12854/erde-147-8 %T Challenging the current climate change – migration nexus: exploring migrants’ perceptions of climate change in the hosting country %U https://doi.org/10.12854/erde-147-8 2 %X Along with the growing scientific and political concern on global warming, the relationship of climate and migration is framed as cause and consequence. Alarmist numbers of mass migration and related conflicts currently represent the main scientific narratives merging the issue of migration and climate change. This paper takes a different and explorative perspective: it suggests that scientific discourses on migration and climate change should be reframed by taking into consideration the diverse ‘knowledges’ offered by migrants. Employing an experimentalist approach, we aim at filling this gap in research and introduce an empirical perspective on climate framings among Italian and Chinese citizens in the local context of the city of Hamburg (Germany). Qualitatively analysing semi-structured interviews, the paper conveys an in-depth analysis of how Italian and Chinese migrants frame climate change and, furthermore, explores philosophical backgrounds informing them. We start with a theoretical and methodological outline on undertaking research with migrants and then turn to an empirical analysis in which we examine and discuss four prevailing categories found in the course of our investigation. The final section summarises the results and reflects upon the methodological and theoretical approach applied which refers to the relevance of migrants as active actors in local adaptation and mitigation processes of the hosting country. %0 journal article %@ 1463-5003 %A Schulz-Stellenfleth, J., Stanev, E.V. %D 2016 %J Ocean Modelling %P 109-124 %R doi:10.1016/j.ocemod.2016.02.002 %T Analysis of the upscaling problem – A case study for the barotropic dynamics in the North Sea and the German Bight %U https://doi.org/10.1016/j.ocemod.2016.02.002 %X The upscaling problem is investigated using the barotropic dynamics of the North Sea and the German Bight as an example. The impact of small scale perturbations of bathymetry, bottom roughness, wind forcing, and boundary forcing is quantified using a two-dimensional linear barotropic model for the entire North Sea with 5 km resolution. The model is solved in the spectral domain for the dominant M2 tide. Comparisons with results from a fully nonlinear 3D circulation model show that the main circulation features are well captured by the spectral model. The impact of different types of perturbations is estimated by inversion of the model using the perturbation covariance matrix as input. Case studies with white noise and fully correlated noise are presented. It is shown that the German Bight area stands out in its sensitivity with respect to small scale uncertainties of bathymetry. Small scale changes of bottom roughness have a particularly strong effect in the English Channel. Small scale wind perturbations have a significant local effect only in very shallow near coastal areas. It is shown that uncorrelated noise introduced along an open boundary around the German Bight only has a very local effect. Perturbations with long correlation length are shown to lead to significant far field effects along the east coast of England. It is demonstrated that this effect is related to the boundary conditions used for the North Sea model. In a next step a German Bight grid with 1 km resolution is nested into the North Sea grid and the spectral model is solved in a two way nested configuration. It is shown that there are some significant local and far field effects caused by the change of resolution in this coastal area. Finally, the potential impact of observations taken in coastal areas is investigated by evaluating the Kalman a posteriori distribution of analysis vectors based on different assumptions about model errors. The area of influence of a single tide gauge is quantified for the case where the model errors are dominated by boundary forcing errors. The results show a strong dependence on spatial correlation properties of the errors. %0 journal article %@ 1616-7341 %A Jacob, B., Stanev, E.V., Zhang, Y.J. %D 2016 %J Ocean Dynamics %N 5 %P 671-690 %R doi:10.1007/s10236-016-0949-8 %T Local and remote response of the North Sea dynamics to morphodynamic changes in the Wadden Sea %U https://doi.org/10.1007/s10236-016-0949-8 5 %X The response of the tidal system in the southern North Sea to morphodynamic changes was investigated in a modelling study using fine resolution bathymetric observations available for 1982–2011. The Semi-implicit Cross-scale Hydroscience Integrated System Model (SCHISM) was set up for the different sets of bathymetries. One set of bathymetry was compiled from a large number of bathymetric measurements over many years, while the other two reflected bathymetry state in the area of Wadden Sea during 2000 and 2011, respectively. The temporal and spatial evolution of bathymetry was dominated by migration of tidal channels. The M4 tide showed larger sensitivity to bathymetric change in the Wadden Sea than the M2 tide, whereas the structure of the latter remained rather robust. The largest change of the tidal wave due to the differences in bathymetries was located off the North Frisian Wadden Sea. Traces of changes were also found far away from the regions of their origin because the tidal waves in the North Sea propagate the local disturbances basin-wide. This illustrated an efficient physical mechanism of teleconnectivity, i.e. effecting the local responses to the larger-scale or remote change of ocean bottom caused by erosion and deposition. The tidal distortion resulting from the relatively small bathymetric changes was substantial, particularly in the coastal zone. This is a manifestation of the nonlinear tidal transformation in shallow oceans and is crucial for the sediment transport and the morphodynamic feedback, because of the altered tidal asymmetry. %0 journal article %@ 1616-7341 %A Pein, J.U., Grayek, S., Schulz-Stellenfleth, J., Stanev, E.V. %D 2016 %J Ocean Dynamics %N 2 %P 243-262 %R doi:10.1007/s10236-015-0920-0 %T On the impact of salinity observations on state estimates in Ems Estuary %U https://doi.org/10.1007/s10236-015-0920-0 2 %X The hydrodynamics of Ems Estuary are dominated by tides and their interaction with buoyancy forcing. Such an environment is challenging for any effort to bring together observations and model results. In this study, we investigate how salinity measurements in the Ems Estuary affect the reconstruction of the salinity field. Similar to the traditional observing system experiments, the impact of specific observational arrays is simulated in the framework of statistical experiments. The experimental algorithm mainly relies on the model covariance matrix. Each experiment results in an estimate of the reconstruction error. The analysed observation configurations involve single and multiple, as well as stationary and non-stationary observing arrays. Generally, the reconstruction of the ocean state improves with increasing the density of observations. It appears that certain locations are more favourable for reconstruction than others. In fact, the regions separating the main dynamical realms resist strongest to the reconstruction effort. Extending the covariance matrix by the temporal cross-covariances between the model grid points enables to evaluate the impact of observations taken from a moving platform. This approach further improves the outcome of the experiments, resulting in reconstruction errors near zero with the exception of the tidal river. The cross-covariance information is able to tackle even the irregular dynamics arising on the border between the different physical regimes. %0 journal article %@ 1463-5003 %A Zhang, Y.J., Stanev, E.V., Grashorn, S. %D 2016 %J Ocean Modelling %P 91-108 %R doi:10.1016/j.ocemod.2015.11.009 %T Unstructured-grid model for the North Sea and Baltic Sea: Validation against observations %U https://doi.org/10.1016/j.ocemod.2015.11.009 %X A new unstructured-grid model and its application to the North Sea and Baltic Sea are described. The research focus is on the dynamics in the two basins and in the multiple straits connecting them and more specifically on how the model replicates the temporal and spatial variability of physical processes. The comparison against observed data indicates the realism in the simulations of the exchange flows. The simulations demonstrated that in contrast to the tidal variability which decreases in the strait, the role of the barotropic forcing due to weather systems increases. In this zone reversal of transport is well manifested by the increased difference between the surface and bottom salinity values. Small sub-basins like Arkona and Bornholm play the role of reservoirs for denser water which under specific conditions cascades on its way to the Gotland Deep. Unlike the intermediate and deep water salinity in the Baltic Sea, which is strongly affected by fluxes in the straits, the simulated winter-refill and evolution of cold intermediate water are rather driven by surface cooling and processes in the upper mixed layer. %0 journal article %@ 1812-0784 %A She, J., Allen, I., Buch, E., Crise, A., Johannessen, J.A., Le Traon, P.-Y., Lips, U., Nolan, G., Pinardi, N., Reissmann, J.H., Siddorn, J., Stanev, E., Wehde, H. %D 2016 %J Ocean Science %N 4 %P 953-976 %R doi:10.5194/os-12-953-2016 %T Developing European operational oceanography for Blue Growth, climate change adaptation and mitigation, and ecosystem-based management %U https://doi.org/10.5194/os-12-953-2016 4 %X Operational approaches have been more and more widely developed and used for providing marine data and information services for different socio-economic sectors of the Blue Growth and to advance knowledge about the marine environment. The objective of operational oceanographic research is to develop and improve the efficiency, timeliness, robustness and product quality of this approach. This white paper aims to address key scientific challenges and research priorities for the development of operational oceanography in Europe for the next 5–10 years. Knowledge gaps and deficiencies are identified in relation to common scientific challenges in four EuroGOOS knowledge areas: European Ocean Observations, Modelling and Forecasting Technology, Coastal Operational Oceanography and Operational Ecology. The areas “European Ocean Observations” and “Modelling and Forecasting Technology” focus on the further advancement of the basic instruments and capacities for European operational oceanography, while “Coastal Operational Oceanography” and “Operational Ecology” aim at developing new operational approaches for the corresponding knowledge areas. %0 journal article %@ 1463-5003 %A Zhang, Y.J., Ye, F., Stanev, E.V., Grashorn, S. %D 2016 %J Ocean Modelling %P 64-81 %R doi:10.1016/j.ocemod.2016.05.002 %T Seamless cross-scale modeling with SCHISM %U https://doi.org/10.1016/j.ocemod.2016.05.002 %X We present a new 3D unstructured-grid model (SCHISM) which is an upgrade from an existing model (SELFE). The new advection scheme for the momentum equation includes an iterative smoother to reduce excess mass produced by higher-order kriging method, and a new viscosity formulation is shown to work robustly for generic unstructured grids and effectively filter out spurious modes without introducing excessive dissipation. A new higher-order implicit advection scheme for transport (TVD2) is proposed to effectively handle a wide range of Courant numbers as commonly found in typical cross-scale applications. The addition of quadrangular elements into the model, together with a recently proposed, highly flexible vertical grid system (Zhang et al., A new vertical coordinate system for a 3D unstructured-grid model. Ocean Model. 85, 2015), leads to model polymorphism that unifies 1D/2DH/2DV/3D cells in a single model grid. Results from several test cases demonstrate the model's good performance in the eddying regime, which presents greater challenges for unstructured-grid models and represents the last missing link for our cross-scale model. The model can thus be used to simulate cross-scale processes in a seamless fashion (i.e. from deep ocean into shallow depths). %0 journal article %@ 2213-3054 %A Holdschlag, A., Ratter, B.M.W. %D 2016 %J Anthropocene %P 80-93 %R doi:10.1016/j.ancene.2016.03.002 %T Caribbean island states in a social-ecological panarchy? Complexity theory, adaptability and environmental knowledge systems %U https://doi.org/10.1016/j.ancene.2016.03.002 %X Many social-ecologically sensitive Small Island Developing States (SIDS) increasingly face global (climate) change risks to sustainable development. However, the validity of factors said to contribute toward vulnerability is disputed in light of the differing economic success, enormous heterogeneity, divergent paths of development, and varying potential for adaptability displayed by small islands. Research on uncertainty, vulnerability and resilience of coupled social-ecological systems (SES) can provide a valuable contribution to the sustainability debate. Based on the fundamentals of complexity theory, the notions of social-ecological adaptability, and panarchy, this article highlights the role of context-based, hybrid, and limited environmental knowledge and risk knowledge systems and cultures. The modes of organization of disaster management in Grenada (Eastern Caribbean) and environmental governance in The Bahamas (Western Caribbean) on various spatio-temporal scales serve as case studies. The production and communication of knowledge, the difficult (cross-scale) integration of diverse knowledge systems, the role of experience and memory, as well as social/institutional learning and inertia appear as significant factors as regards the strengthening of social adaptability. The findings further demonstrate that significant challenges remain for Caribbean SIDS. These include long-term, socially, locally, and sectorally differentiated vulnerabilities; deficits in governance and communication; and the diverging and spatially-temporally bounded nature of knowledge systems. %0 journal article %@ 2190-1090 %A Grosfeld, K., Lemke, P., Braesicke, P., Brauer, A., Dethloff, K., Kunz, M., Latif, M., Ratter, B., Sachs, T., Schmid, H.P., Treffeisen, R., Schwarze, R. %D 2016 %J Polarforschung %N 2 %P 65-68 %R doi:10.2312/polfor.2016.001 %T The Helmholtz Regional Climate Initiative REKLIM from a Polar Perspective – A Preface %U https://doi.org/10.2312/polfor.2016.001 2 %X warming since the mid-20th century (IPCC 2013). %0 journal article %@ 1726-4170 %A Capet, A., Stanev, E.V., Beckers, J.M., Murray, J.W., Gregoire, M. %D 2016 %J Biogeosciences %N 4 %P 1287-1297 %R doi:10.5194/bg-13-1287-2016 %T Decline of the Black Sea oxygen inventory %U https://doi.org/10.5194/bg-13-1287-2016 4 %X As both atmospheric warming and eutrophication are expected to increase in the near future, monitoring the dynamics of the Black Sea oxic layer is urgently required to assess the threat of further shoaling. %0 journal article %@ 0142-7873 %A Mandal, S., Homma, H., Priyadarshi, A., Burchard, H., Smith, S.L., Wirtz, K.W., Yamazaki, H. %D 2016 %J Journal of Plankton Research %N 4 %P 964-976 %R doi:10.1093/plankt/fbw019 %T A 1D physical–biological model of the impact of highly intermittent phytoplankton distributions %U https://doi.org/10.1093/plankt/fbw019 4 %X Highly intermittent spatial variability of phytoplankton is observed ubiquitously in marine ecosystems, especially when measurements are performed at the micro-scale level. Therefore, theoretical developments and new modelling tools are required to understand the observed small-scale vertical structure and its relationship to ecosystem behaviour. Nearly all current ecosystem models are formulated entirely based on the mean field approximation, ignoring sub-grid scale variability. Even if such approximation may be reasonable for meso-scales (and above), it cannot account for micro-scale dynamics, which may also impact macroscopic properties at the larger scale. To consider intermittency of variables in plankton ecosystem models, we apply a newly developed modelling approach called the closure approach. Detailed simulations were conducted, combining fluid-dynamics of the 1D water column with the nutrient-phytoplankton closure ecosystem model for application to a site in the northern North Sea. Compared with a control model, which does not account for such intermittency, the closure model produced substantially different spatio-temporal patterns of mean phytoplankton biomass and growth rate, which depended on the overall level of variability. In this study, we (i) seek to explore the effects of sub-scale variability coupled with physical transport and (ii) begin to address the yet unresolved question of how to consistently model the advection and diffusion of the variances and co-variances used to represent sub-scale variability in the closure approach. Our results suggest that it may be necessary to account explicitly for the intermittent distribution of plankton and nutrients, even in large-scale biogeochemical models. %0 journal article %@ 2296-701X %A Wirtz, K.W., Kerimoglu, O. %D 2016 %J Frontiers in Ecology and Evolution %P 131 %R doi:10.3389/fevo.2016.00131 %T Autotrophic Stoichiometry Emerging from Optimality and Variable Co-limitation %U https://doi.org/10.3389/fevo.2016.00131 %X Autotrophic organisms reveal an astounding flexibility in their elemental stoichiometry, with potentially major implications on biogeochemical cycles and ecological functioning. Notwithstanding, stoichiometric regulation, and co-limitation by multiple resources in autotrophs were in the past often described by heuristic formulations. In this study, we present a mechanistic model of autotroph growth, which features two major improvements over the existing schemes. First, we introduce the concept of metabolic network independence that defines the degree of phase-locking between accessory machines. Network independence is in particular suggested to be proportional to protein synthesis capability as quantified by variable intracellular N:C. Consequently, the degree of co-limitation becomes variable, contrasting with the dichotomous debate on the use of Liebig's law or the product rule, standing for constantly low and high co-limitation, respectively. Second, we resolve dynamic protein partitioning to light harvesting, carboxylation processes, and to an arbitrary number of nutrient acquisition machineries, as well as instantaneous activity regulation of nutrient uptake. For all regulatory processes we assume growth rate optimality, here extended by an explicit consideration of indirect feed-back effects. The combination of network independence and optimal regulation displays unprecedented skill in reproducing rich stoichiometric patterns collected from a large number of published chemostat experiments. This high skill indicates (1) that the current paradigm of fixed co-limitation is a critical short-coming of conventional models, and (2) that stoichiometric flexibility in autotrophs possibly reflects an optimality strategy. Numerical experiments furthermore show that regulatory mechanisms homogenize the effect of multiple stressors. Extended optimality alleviates the effect of the most limiting resource(s) while down-regulating machineries for the less limiting ones, which induces an ubiquitous response surface of growth rate over ambient resource levels. Our approach constitutes a basis for improved mechanistic understanding and modeling of acclimative processes in autotrophic organisms. It hence may serve future experimental and theoretical investigations on the role of those processes in aquatic and terrestrial ecosystems. %0 journal article %@ 1752-0894 %A Buentgen, U., Myglan, V.S., Ljungqvist, F.C., McCormick, M., Di Cosmo, N., Sigl, M., Jungclaus, J., Wagner, S., Krusic, P.J., Esper, J., kaplan, J.O., de Vaan, M.A.C., Luterbacher, J., Wacker, L., Tegel, W., Solomina, O.N., Nicolussi, K., Oppenheimer, C., Reinig, F., Kirdyanov, A.V. %D 2016 %J Nature Geoscience %P 231-236 %R doi:10.1038/ngeo2652 %T Cooling and societal change during the Late Antique Little Ice Age from 536 to around 660 AD %U https://doi.org/10.1038/ngeo2652 %X Climatic changes during the first half of the Common Era have been suggested to play a role in societal reorganizations in Europe1, 2 and Asia3, 4. In particular, the sixth century coincides with rising and falling civilizations1, 2, 3, 4, 5, 6, pandemics7, 8, human migration and political turmoil8, 9, 10, 11, 12, 13. Our understanding of the magnitude and spatial extent as well as the possible causes and concurrences of climate change during this period is, however, still limited. Here we use tree-ring chronologies from the Russian Altai and European Alps to reconstruct summer temperatures over the past two millennia. We find an unprecedented, long-lasting and spatially synchronized cooling following a cluster of large volcanic eruptions in 536, 540 and 547 AD (ref. 14), which was probably sustained by ocean and sea-ice feedbacks15, 16, as well as a solar minimum17. We thus identify the interval from 536 to about 660 AD as the Late Antique Little Ice Age. Spanning most of the Northern Hemisphere, we suggest that this cold phase be considered as an additional environmental factor contributing to the establishment of the Justinian plague7, 8, transformation of the eastern Roman Empire and collapse of the Sasanian Empire1, 2, 5, movements out of the Asian steppe and Arabian Peninsula8, 11, 12, spread of Slavic-speaking peoples9, 10 and political upheavals in China13. %0 journal article %@ 1616-7341 %A Grashorn, S., Stanev, E.V. %D 2016 %J Ocean Dynamics %N 12 %P 1543-1557 %R doi:10.1007/s10236-016-0995-2 %T Kármán vortex and turbulent wake generation by wind park piles %U https://doi.org/10.1007/s10236-016-0995-2 12 %X Observational evidence of turbulent wakes behind wind parks’ piles motivated a series of numerical experiments, aiming to identify the dynamic regimes associated with wakes’ generation in tidal basins. We demonstrate that the obstacles such as piles of wind parks give rise to vortices similar to the known Kármán vortices which affect substantially the turbulent kinetic energy. The latter can be considered as the agent enhancing sediment remobilization from the ocean bottom, thus making wakes well visible in satellite data. The temporal and spatial variability of studied processes is analyzed under stationary and nonstationary conditions. The dependence of a vortex generation and evolution upon the environmental conditions is also studied, which demonstrates a large variety of appearances of turbulent wakes. The comparison between simulations using a suspended sediment model and satellite images demonstrated that the model is capable to realistically simulate sediment wakes observed in remote sensing data. %0 journal article %@ 2169-9275 %A Zhang, W., Cui, Y., Santos, A.I., Hanebuth, T.J.J. %D 2016 %J Journal of Geophysical Research : Oceans %N 8 %P 5751-5772 %R doi:10.1002/2015JC011526 %T Storm-driven bottom sediment transport on a high-energy narrow shelf (NW Iberia) and development of mud depocenters %U https://doi.org/10.1002/2015JC011526 8 %X Bottom sediment transport on the NW Iberian shelf was monitored during a downwelling storm in September 2014. Collected data were analyzed and fed into a 3-D coastal ocean model to understand storm-driven sediment transport on the shelf and its impact on midshelf mud depocenters (MDCs). A significantly enhanced level of bottom sediment resuspension, nearly two orders of magnitude higher than that in the prestorm period, was recorded at the mooring site. Field data analysis reveals that it was induced by a short-lasting strong bottom current in combination with enhanced wave-current interaction. Simulation results indicate that this strong current was part of a coastal jet resulted from downwelling. An across-shelf horizontal density gradient as high as 0.32 g/m4 occurred at the interface between the downwelling and the bottom waters, forming a remarkable front. Due to buoyancy effect, the downwelling water was mostly confined to the coast with a depth limit of 80 m in the south and 120 m in the north of the region, resulting in a northward-directed coastal jet. Simulation results suggest that during the storm, local near-bottom sediment suspensions with concentrations on the order of 10 kg/m3 would be triggered by wave-current interaction and flow convergence associated with the front. Direct impact on the development of MDCs by transport and deposition of concentrated sediment suspensions is indicated by model results. The seaward limit of the front coincided with the shoreward edge of the MDC nucleus, suggesting the front as a primary control on the deposition of fine-grained sediment. %0 journal article %@ 0277-3791 %A Vanniere, B., Blarquez, O., Rius, D., Doyen, E., Bruecher, T., Colombaroli, D., Connor, S., Feurdean, A., Hickler, T., Kaltenrieder, P., Lemmen, C., Leys, B., Massa, C., Olofsson, J. %D 2016 %J Quaternary Science Reviews %P 2016-212 %R doi:10.1016/j.quascirev.2015.11.012 %T 7000-year human legacy of elevation-dependent European fire regimes %U https://doi.org/10.1016/j.quascirev.2015.11.012 %X Variability in fire regime at the continental scale has primarily been attributed to climate change, often overshadowing the widely potential impact of human activities. However, human ignition modifies the rhythm of fire episodes occurrence (fire frequency), whereas land use alters vegetation composition and fuel load, and thus the amount of biomass burned. It is unclear, however, whether and how humans have exercised a significant influence over fire regimes at continental and millennial scales. Based on sedimentary charcoal records, we use new alternative estimate of fire frequency and biomass burned for the last 16000 years (here after 16 ky) that we evaluate with outputs from climate, vegetation, land use and population models. We find that pronounced regional-scale land use changes in southern Europe at the beginning of the Neolithic (8–6 ky), during the Bronze Age (5–4 ky) and the medieval period (1 ky) caused a doubling of fire frequency compared to the Holocene average (the last 11.5 ky). Despite anthropogenic influences, southern European biomass burned decreased from 7 ky, which is in line both with changes in orbital parameters leading climate cooling and also reductions in biomass availability because of land use. Our study underscores the role of elevation-dependent parameters, and particularly biomass and land management, as major drivers of fire regime variability. Results attest a determinant anthropogenic driving-force on fire regime and a decrease in fire-carbon emissions since 7 ky in Southern Europe. %0 journal article %@ 1616-7341 %A Behrens, A. %D 2015 %J Ocean Dynamics %N 4 %P 469-486 %R doi:10.1007/s10236-015-0825-y %T Development of an ensemble prediction system for ocean surface waves in a coastal area %U https://doi.org/10.1007/s10236-015-0825-y 4 %X An ensemble prediction system for ocean surface waves has been developed and applied on a local scale to the German Bight and the western Baltic Sea. U10-wind fields generated by the COSMO-DE-EPS upstream forecast chain of the German Met Service (DWD: Deutscher Wetterdienst) have been used as the driving force for the third-generation spectral wave model WAM. The atmospheric chain includes four different global models that provide boundary values for four regional COSMO-EU realisations. Each of those drive five COSMO-DE members, respectively, with different sets of physical parameterisations, so that finally 20 members are available to run 20 corresponding wave ensemble members of the coastal wave model CWAM (Coastal WAve Model) for the German Bight and the western Baltic Sea. It is the first time that in an ensemble prediction system for ocean waves, an atmospheric model of such a fine spatial resolution of 2.8 km has been combined with a wave model running on a model grid with a mesh size of 900 m only. Test runs with the wave ensemble prediction system have been executed for two entire months (April 2013 and June 2014) and for an 8-day storm case (Xaver) in December 2013 in order to check whether such a system could be a reasonable step to improve the future operational wave forecasts of the DWD. The results computed by the different wave model members agree fairly well with available buoy data. The differences between the results for the integrated wave parameters of the individual members are small only, but more pronounced in extreme storm situations. Finally, the statistical analysis of the comparisons with measurements show without exception slightly improved values for the ensemble mean of the wave ensemble members compared with the usual deterministic routine control run. %0 journal article %@ 1812-0784 %A Tim, N., Zorita, E., Huenicke, B. %D 2015 %J Ocean Science %N 3 %P 483-502 %R doi:10.5194/os-11-483-2015 %T Decadal variability and trends of the Benguela upwelling system as simulated in a high-resolution ocean simulation %U https://doi.org/10.5194/os-11-483-2015 3 %X Detecting the atmospheric drivers of the Benguela upwelling systems is essential to understand its present variability and its past and future changes. We present a statistical analysis of a high-resolution (0.1°) ocean-only simulation driven by observed atmospheric fields over the last 60 years with the aim of identifying the large-scale atmospheric drivers of upwelling variability and trends. The simulation is found to reproduce well the seasonal cycle of upwelling intensity, with a maximum in the June–August season in North Benguela and in the December–February season in South Benguela. The statistical analysis of the interannual variability of upwelling focuses on its relationship to atmospheric variables (sea level pressure, 10 m wind, wind stress). The relationship between upwelling and the atmospheric variables differ somewhat in the two regions, but generally the correlation patterns reflect the common atmospheric pattern favouring upwelling: southerly wind/wind stress, strong subtropical anticyclone, and an ocean–land sea level pressure gradient. In addition, the statistical link between upwelling and large-scale climate variability modes was analysed. The El Niño–Southern Oscillation and the Antarctic Oscillation exert some influence on austral summer upwelling velocities in South Benguela. The decadal evolution and the long-term trends of simulated upwelling and of ocean-minus-land air pressure gradient do not agree with Bakun's hypothesis that anthropogenic climate change should generally intensify coastal upwelling. %0 journal article %@ 1616-7341 %A Grashorn, S., Lettmann, K.A., Wolff, J.-O., Badewien, T.H., Stanev, E.V. %D 2015 %J Ocean Dynamics %N 3 %P 419-434 %R doi:10.1007/s10236-014-0807-5 %T East Frisian Wadden Sea hydrodynamics and wave effects in an unstructured-grid model %U https://doi.org/10.1007/s10236-014-0807-5 3 %X An unstructured-grid model (FVCOM) coupled to a surface wave model (FVCOM-SWAVE) with two different setups is used to investigate the hydrodynamic and wave energy conditions during a moderate wind and a storm situation in the southern North Sea. One setup covers the whole North Sea with moderately increased grid resolution at the coast, whereas the other is a very high-resolution Wadden Sea setup that is one-way coupled to the coarser North Sea model. The results of both model setups are validated, compared to each other and analysed with a focus on longshore currents and wave energy. The numerical results show that during storm conditions, strong wave-induced longshore currents occur in front of the East Frisian Wadden Sea islands with current speeds up to 1 m/s. The model setup with the higher resolution around the islands shows even stronger currents than the coarser setup. The wave-current interaction also influences the surface elevation by raising the water level in the tidal basins. The calculated wave energies show large differences between moderate wind and storm conditions with time-averaged values up to 200 kW/m. %0 journal article %@ 0034-6853 %A Prein, A.F., Langhans, W., Fosser, G., Ferrone, A., Ban, N., Goergen, K., Keller, M., Toelle, M., Gutjahr, O., Feser, F., Brisson, E., Kollet, S., Schmidli, J., Lipzig, N.P.M.van, Leung, R. %D 2015 %J Reviews of Geophysics %N 2 %P 323-361 %R doi:10.1002/2014RG000475 %T A review on regional convection-permitting climate modeling: Demonstrations, prospects, and challenges %U https://doi.org/10.1002/2014RG000475 2 %X Regional climate modeling using convection-permitting models (CPMs; horizontal grid spacing <4 km) emerges as a promising framework to provide more reliable climate information on regional to local scales compared to traditionally used large-scale models (LSMs; horizontal grid spacing >10 km). CPMs no longer rely on convection parameterization schemes, which had been identified as a major source of errors and uncertainties in LSMs. Moreover, CPMs allow for a more accurate representation of surface and orography fields. The drawback of CPMs is the high demand on computational resources. For this reason, first CPM climate simulations only appeared a decade ago. In this study, we aim to provide a common basis for CPM climate simulations by giving a holistic review of the topic. The most important components in CPMs such as physical parameterizations and dynamical formulations are discussed critically. An overview of weaknesses and an outlook on required future developments is provided. Most importantly, this review presents the consolidated outcome of studies that addressed the added value of CPM climate simulations compared to LSMs. Improvements are evident mostly for climate statistics related to deep convection, mountainous regions, or extreme events. The climate change signals of CPM simulations suggest an increase in flash floods, changes in hail storm characteristics, and reductions in the snowpack over mountains. In conclusion, CPMs are a very promising tool for future climate research. However, coordinated modeling programs are crucially needed to advance parameterizations of unresolved physics and to assess the full potential of CPMs. %0 journal article %@ 1814-9324 %A Santos, J.A., Carneiro, M.F., Correia, A., Alcoforado, M.J., Zorita, E., Gomez-Navarro, J.J. %D 2015 %J Climate of the Past %N 6 %P 825-834 %R doi:10.5194/cp-11-825-2015 %T New insights into the reconstructed temperature in Portugal over the last 400 years %U https://doi.org/10.5194/cp-11-825-2015 6 %X The consistency of an existing reconstructed annual (December–November) temperature series for the Lisbon region (Portugal) from 1600 onwards, based on a European-wide reconstruction, with (1) five local borehole temperature–depth profiles; (2) synthetic temperature–depth profiles, generated from both reconstructed temperatures and two regional paleoclimate simulations in Portugal; (3) instrumental data sources over the twentieth century; and (4) temperature indices from documentary sources during the late Maunder Minimum (1675–1715) is assessed. The low-frequency variability in the reconstructed temperature in Portugal is not entirely consistent with local borehole temperature–depth profiles and with the simulated response of temperature in two regional paleoclimate simulations driven by reconstructions of various climate forcings. Therefore, the existing reconstructed series is calibrated by adjusting its low-frequency variability to the simulations (first-stage adjustment). The annual reconstructed series is then calibrated in its location and scale parameters, using the instrumental series and a linear regression between them (second-stage adjustment). This calibrated series shows clear footprints of the Maunder and Dalton minima, commonly related to changes in solar activity and explosive volcanic eruptions, and a strong recent-past warming, commonly related to human-driven forcing. Lastly, it is also in overall agreement with annual temperature indices over the late Maunder Minimum in Portugal. The series resulting from this post-reconstruction adjustment can be of foremost relevance to improve the current understanding of the driving mechanisms of climate variability in Portugal. %0 journal article %@ 1680-7316 %A Zhu, J., Wang, T., Bieser, J., Matthias, V. %D 2015 %J Atmospheric Chemistry and Physics %N 15 %P 8767-8779 %R doi:10.5194/acp-15-8767-2015 %T Source attribution and process analysis for atmospheric mercury in eastern China simulated by CMAQ-Hg %U https://doi.org/10.5194/acp-15-8767-2015 15 %X The contribution from different emission sources and atmospheric processes to gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), particulate bound mercury (PBM) and mercury deposition in eastern China were quantified using the Community Multi-scale Air Quality (CMAQ-Hg) modeling system run with a nested domain. Natural sources (NAT) and six categories of anthropogenic mercury sources (ANTH) including cement production (CEM), domestic life (DOM), industrial boilers (IND), metal production (MET), coal-fired power plants (PP) and traffic (TRA) were considered for source apportionment. NAT were responsible for 36.6 % of annual averaged GEM concentration, which was regarded as the most important source for GEM in spite of obvious seasonal variation. Among ANTH, the influence of MET and PP on GEM were most evident especially in winter. ANTH dominated the variations of GOM and PBM concentrations with contributions of 86.7 and 79.1 %, respectively. Among ANTH, IND were the largest contributor for GOM (57.5 %) and PBM (34.4 %) so that most mercury deposition came from IND. The effect of mercury emitted from out of China was indicated by a > 30 % contribution to GEM concentration and wet deposition. The contributions from nine processes – consisting of emissions (EMIS), gas-phase chemical production/loss (CHEM), horizontal advection (HADV), vertical advection (ZADV), horizontal advection (HDIF), vertical diffusion (VDIF), dry deposition (DDEP), cloud processes (CLDS) and aerosol processes (AERO) – were calculated for process analysis with their comparison in urban and non-urban regions of the Yangtze River delta (YRD). EMIS and VDIF affected surface GEM and PBM concentrations most and tended to compensate each other all the time in both urban and non-urban areas. However, DDEP was the most important removal process for GOM with 7.3 and 2.9 ng m−3 reduced in the surface of urban and non-urban areas, respectively, in 1 day. The diurnal profile variation of processes revealed the transportation of GOM from urban area to non-urban areas and the importance of CHEM/AERO in higher altitudes which partly caused diffusion of GOM downwards to non-urban areas. Most of the anthropogenic mercury was transported and diffused away from urban areas by HADV and VDIF and increased mercury concentrations in non-urban areas by HADV. Natural emissions only influenced CHEM and AERO more significantly than anthropogenic. Local emissions in the YRD contributed 8.5 % more to GEM and ~ 30 % more to GOM and PBM in urban areas compared to non-urban areas. %0 journal article %@ 1824-2049 %A Feser, F. %D 2015 %J Journal of Science Communication :JCOM %N 1 %P C02 %R doi:10.22323/2.14010302 %T Comment: The visiting artist researcher experiment %U https://doi.org/10.22323/2.14010302 1 %X The visiting artist researcher experiment discussed here brought together visual artists and climate scientists, amongst them my research group which studies storms. The artists’ stay led to a dialogue between our diverging perspectives and an open exchange of ideas. The exchange in my research group was more interactive than I had expected. Many conversations provided insights into ideas and work flows of the artists and, eventually, a new view on our storm studies. %0 journal article %@ 2194-6434 %A Weisse, R., Bisling, P., Gaslikova, L., Geyer, B., Groll, N., Hortamani, M., Matthias, V., Maneke, M., Meinke, I., Meyer, E., Schwichtenberg, F., Stempinski, F., Wiese, F., Woeckner-Kluwe, K. %D 2015 %J Earth Perspectives %P 3 %R doi:10.1186/s40322-015-0029-0 %T Climate services for marine applications in Europe %U https://doi.org/10.1186/s40322-015-0029-0 %X The term “climate services” is commonly used to refer to the generation of climate information, their transformation according to user needs and the subsequent use of the information in decision making processes. More generally, the concept also involves contextualization of information and knowledge. In the following a series of examples from the marine sector is described covering the generation, transformation and the use of climate information in decision making processes while contextualization is not considered. Examples comprise applications from naval architecture, offshore wind and more generally renewable energies, shipping emissions, and tidal basin water exchange and eutrophication levels. Moreover effects of climate change on coastal flood damages and the need for coastal protection are considered. Based on the analysis of these examples it is concluded that reliable climate information in data sparse regions is urgently needed, that for many applications historical climate information may be as or even more important as future long-term projections, and that the specific needs of different sectors substantially depend on their planning horizons. %0 journal article %@ 1708-3087 %A Gilbert, A.J., Alexander, K., Sarda, R., Brazinskaite, R., Fischer, C., Gee, K., Jessopp, M., Kershaw, P., Los, H.J., Morla, D.M., O´Mahony, C., Pihlajamaeki, M., Rees, S., Varjopuro, R. %D 2015 %J Ecology and Society %N 1 %P 64 %R doi:10.5751/ES-06979-200164 %T Marine spatial planning and Good Environmental Status: A perspective on spatial and temporal dimensions %U https://doi.org/10.5751/ES-06979-200164 1 %X The European Union Marine Strategy Framework Directive requires the Good Environmental Status of marine environments in Europe's regional seas; yet, maritime activities, including sources of marine degradation, are diversifying and intensifying in an increasingly globalized world. Marine spatial planning is emerging as a tool for rationalizing competing uses of the marine environment while guarding its quality. A directive guiding the development of such plans by European Union member states is currently being formulated. There is an undeniable need for marine spatial planning. However, we argue that considerable care must be taken with marine spatial planning, as the spatial and temporal scales of maritime activities and of Good Environmental Status may be mismatched. We identify four principles for careful and explicit consideration to align the requirements of the two directives and enable marine spatial planning to support the achievement of Good Environmental Status in Europe's regional seas. %0 journal article %@ 1708-3087 %A Blenckner, T., Kannen, A., Barausse, A., Fischer, C., Heymans, J.J., Luisetti, T., Todorova, V., Valman, M., Mee, L. %D 2015 %J Ecology and Society %N 1 %P 40 %R doi:10.5751/ES-07246-200140 %T Past and future challenges in managing European seas %U https://doi.org/10.5751/ES-07246-200140 1 %X Marine environments have undergone large-scale changes in recent decades as a result of multiple anthropogenic pressures, such as overfishing, eutrophication, habitat fragmentation, etc., causing often nonlinear ecosystem responses. At the same time, management institutions lack the appropriate measures to address these abrupt transformations. We focus on existing examples from social–ecological systems of European seas that can be used to inform and advise future management. Examples from the Black Sea and the Baltic Sea on long-term ecosystem changes caused by eutrophication and fisheries, as well as changes in management institutions, illustrate nonlinear dynamics in social–ecological systems. Furthermore, we present two major future challenges, i.e., climate change and energy intensification, that could further increase the potential for nonlinear changes in the near future. Practical tools to address these challenges are presented, such as ensuring learning, flexibility, and networking in decision-making processes across sectors and scales. A combination of risk analysis with a scenario-planning approach might help to identify the risks of ecosystem changes early on and may frame societal changes to inform decision-making structures to proactively prevent drastic surprises in European seas. %0 journal article %@ 0930-7575 %A Gomez-Navarro, J.J., Werner, J., Wagner, S., Luterbacher, J., Zorita, E. %D 2015 %J Climate Dynamics %N 5 %P 1395-1413 %R doi:10.1007/s00382-014-2388-x %T Establishing the skill of climate field reconstruction techniques for precipitation with pseudoproxy experiments %U https://doi.org/10.1007/s00382-014-2388-x 5 %X This study aims at assessing the skill of several climate field reconstruction techniques (CFR) to reconstruct past precipitation over continental Europe and the Mediterranean at seasonal time scales over the last two millennia from proxy records. A number of pseudoproxy experiments are performed within the virtual reality of a regional paleoclimate simulation at 45 km resolution to analyse different aspects of reconstruction skill. Canonical Correlation Analysis (CCA), two versions of an Analog Method (AM) and Bayesian hierarchical modeling (BHM) are applied to reconstruct precipitation from a synthetic network of pseudoproxies that are contaminated with various types of noise. The skill of the derived reconstructions is assessed through comparison with precipitation simulated by the regional climate model. Unlike BHM, CCA systematically underestimates the variance. The AM can be adjusted to overcome this shortcoming, presenting an intermediate behaviour between the two aforementioned techniques. However, a trade-off between reconstruction-target correlations and reconstructed variance is the drawback of all CFR techniques. CCA (BHM) presents the largest (lowest) skill in preserving the temporal evolution, whereas the AM can be tuned to reproduce better correlation at the expense of losing variance. While BHM has been shown to perform well for temperatures, it relies heavily on prescribed spatial correlation lengths. While this assumption is valid for temperature, it is hardly warranted for precipitation. In general, none of the methods outperforms the other. All experiments agree that a dense and regularly distributed proxy network is required to reconstruct precipitation accurately, reflecting its high spatial and temporal variability. This is especially true in summer, when a specifically short de-correlation distance from the proxy location is caused by localised summertime convective precipitation events. %0 journal article %@ 1616-7341 %A Stanev, E.V., Al-Nadhairi, R., Valle-Levinson, A. %D 2015 %J Ocean Dynamics %N 1 %P 77-92 %R doi:10.1007/s10236-014-0784-8 %T The role of density gradients on tidal asymmetries in the German Bight %U https://doi.org/10.1007/s10236-014-0784-8 1 %X The dynamics of the German Bight associated with river plumes and fresh water intrusions from tidal flats have been studied with numerical simulations. The horizontal and vertical patterns of the M2, M4 and M6 tides revealed complex distortions along the bathymetric channels connecting the coast and the open sea. A major focus was on the surface-to-bottom change in tidal asymmetries, which provides a major control on draining the tidal flats around the Elbe and Weser River mouths. Comparisons between baroclinic and barotropic experiments demonstrated that the estuarine gravitational circulation is responsible for pronounced differences in surface and bottom asymmetries. These differences could be considered as a basic control mechanism for sediment dynamics. The most prominent area of tidal distortions, manifested by a delay of the tidal wave, was located between the estuarine turbidity maximum and the estuarine mouth north of Cuxhaven. This area was characterized by the strongest periodic convergence and divergence of the flow and by the largest salinity gradients. The enhancement of the gravitational circulation occurred during the transition between spring and neap tides. The large-scale dynamics and small-scale topographic features could impact the sediment distribution as there was a marked interplay in the channels between stratification and turbulence. Also an explanation has been given for the mechanisms supporting the existence of a mud area (Schlickgebiet) south of Helgoland Island, associated with trapping suspended particular matter. %0 journal article %@ 0148-0227 %A Tsimitri, C., Rockel, B., Wueest, A., Budnev, N.M., Sturm, M., Schmid, M. %D 2015 %J Journal of Geophysical Research : Oceans %N 3 %P 1508-1526 %R doi:10.1002/2014JC010449 %T Drivers of deep-water renewal events observed over 13 years in the South Basin of Lake Baikal %U https://doi.org/10.1002/2014JC010449 3 %X Lake Baikal, with a depth of 1637 m, is characterized by deep-water intrusions that bridge the near-surface layer to the hypolimnion. These episodic events transfer heat and oxygen over large vertical scales and maintain the permanent temperature stratified deep-water status of the lake. Here we evaluate a series of intrusion events that reached the bottom of the lake in terms of the stratification and the wind conditions under which they occurred and provide a new insight into the triggering mechanisms. We make use of long-term temperature and current meter data (2000 to 2013) recorded in the South Basin of the lake combined with wind data produced with a regional downscaling of the global NCEP-RA1 reanalysis product. A total of 13 events were observed during which near-surface cold water reached the bottom of the South Basin at 1350 m depth. We found that the triggering mechanism of the events is related to the time of the year that they take place. We categorized the events in three groups: (1) Winter events, observed shortly before the complete ice cover of the lake that are triggered by Ekman coastal downwelling, (2) under-ice events, and (3) spring events, that show no correlation to the wind conditions and are possibly connected to the increased spring outflow of the Selenga River. %0 journal article %@ 0078-3234 %A Storch, H.v., Emeis, K., Meinke, I., Kannen, A., Matthias, V., Ratter, B.M.W., Stanev, E., Weisse, R., Wirtz, K. %D 2015 %J Oceanologia %N 1 %P 3-16 %R doi:10.1016/j.oceano.2014.09.001 %T Making coastal research useful – Cases from practice %U https://doi.org/10.1016/j.oceano.2014.09.001 1 %X Important issues are the recognition of alternative knowledge claims, the inevitableness of uncertainties and incompleteness of scientific analysis, the acceptance of the political nature of decisions and the ubiquitous presence of social values. Modesty, self-reflexivity and skepticism are needed on the side of science and an organized exchange with stakeholders and public through designated “border” services. %0 journal article %@ 0035-9009 %A Feser, F., Barcikowska, M., Krueger, O., Schenk, F., Weisse, R., Xia, L. %D 2015 %J Quarterly Journal of the Royal Meteorological Society %N 687 %P 350-382 %R doi:10.1002/qj.2364 %T Storminess over the North Atlantic and northwestern Europe - A review %U https://doi.org/10.1002/qj.2364 687 %X Storm trends derived from reanalyses data and climate model data for the past are mostly limited to the last four to six decades. The majority of these studies find increasing storm activity north of about 55–60° N over the North Atlantic with a negative tendency southward. This increase from about the 1970s until the mid-1990s is also mirrored by long-term proxies and the North Atlantic Oscillation and constitutes a part of their decadal variability. Studies based on proxy and measurement data or model studies over the North Atlantic for the past which cover more than 100 years show large decadal variations and either no trend or a decrease in storm numbers. Future scenarios until about the year 2100 indicate mostly an increase in winter storm intensity over the North Atlantic and western Europe. However, future trends in total storm numbers are quite heterogeneous and depend on the model generation used. %0 journal article %@ 1755-876X %A Kourafalou, V., De Mey, P., Staneva, J., Ayoub, N., Barth, A., Chao, Y., Ciranor, M., Fiechter, J. %D 2015 %J Journal of Operational Oceanography %N S 1 %P S147-S167 %R doi:10.1080/1755876X.2015.1022348 %T Coastal Ocean Forecasting: science foundation and user benefits %U https://doi.org/10.1080/1755876X.2015.1022348 S 1 %X The advancement of Coastal Ocean Forecasting Systems (COFS) requires the support of continuous scientific progress addressing: (a) the primary mechanisms driving coastal circulation; (b) methods to achieve fully integrated coastal systems (observations and models), that are dynamically embedded in larger scale systems; and (c) methods to adequately represent air-sea and biophysical interactions. Issues of downscaling, data assimilation, atmosphere-wave-ocean couplings and ecosystem dynamics in the coastal ocean are discussed. These science topics are fundamental for successful COFS, which are connected to evolving downstream applications, dictated by the socioeconomic needs of rapidly increasing coastal populations. %0 journal article %@ 1616-7341 %A Grabemann, I., Groll, N., Moeller, J., Weisse, R. %D 2015 %J Ocean Dynamics %N 2 %P 255-267 %R doi:10.1007/s10236-014-0800-z %T Climate change impact on North Sea wave conditions: a consistent analysis of ten projections %U https://doi.org/10.1007/s10236-014-0800-z 2 %X Long-term changes in the mean and extreme wind wave conditions as they may occur in the course of anthropogenic climate change can influence and endanger human coastal and offshore activities. A set of ten wave climate projections derived from time slice and transient simulations of future conditions is analyzed to estimate the possible impact of anthropogenic climate change on mean and extreme wave conditions in the North Sea. This set includes different combinations of IPCC SRES emission scenarios (A2, B2, A1B, and B1), global and regional models, and initial states. A consistent approach is used to provide a more robust assessment of expected changes and uncertainties. While the spatial patterns and the magnitude of the climate change signals vary, some robust features among the ten projections emerge: mean and severe wave heights tend to increase in the eastern parts of the North Sea towards the end of the twenty-first century in nine to ten projections, but the magnitude of the increase in extreme waves varies in the order of decimeters between these projections. For the western parts of the North Sea more than half of the projections suggest a decrease in mean and extreme wave heights. Comparing the different sources of uncertainties due to models, scenarios, and initial conditions, it can be inferred that the influence of the emission scenario on the climate change signal seems to be less important. Furthermore, the transient projections show strong multi-decadal fluctuations, and changes towards the end of the twenty-first century might partly be associated with internal variability rather than with systematic changes. %0 journal article %@ 1463-5003 %A Wahle, K., Staneva, J., Guenther, H. %D 2015 %J Ocean Modelling %N 1 %P 117-125 %R doi:10.1016/j.ocemod.2015.07.007 %T Data assimilation of ocean wind waves using Neural Networks. A case study for the German Bight %U https://doi.org/10.1016/j.ocemod.2015.07.007 1 %X A novel approach of data assimilation based on Neural Networks (NN’s) is presented and applied to wave modeling in the German Bight. The method takes advantage from the ability of NN’s to emulate models and to invert them. Combining forward and inverse model NN with the Levenberg–Marquardt algorithm provides boundary values or wind fields in agreement with measured wave integrated parameters. Synthesized HF-radar wave data are used to test the technique for two academic cases. %0 journal article %@ 1708-3087 %A Mee, L., Cooper, P., Kannen, A., Gilbert, A.J., O`Higgins, T. %D 2015 %J Ecology and Society %N 1 %P 1 %R doi:10.5751/ES-07143-200101 %T Sustaining Europe’s seas as coupled social-ecological systems %U https://doi.org/10.5751/ES-07143-200101 1 %X Science can help society resolve these problems, but in many cases this requires the broad and integrative vision of Odum’s (1971) “macroscope” rather than trying to piece together an ill-fitting jigsaw puzzle of discipline-focused information. This paper and the others in this Special Feature employ a systems approach. We describe the approach, how it can be applied practically, and some of the challenges in making it work. Though the work is based on research on Europe’s seas, it has much wider implications for regional seas throughout the world. %0 journal article %@ 2198-6061 %A Rockel, B. %D 2015 %J Current Climate Change Reports %N 1 %P 22-29 %R doi:10.1007/s40641-014-0001-3 %T The Regional Downscaling Approach: a Brief History and Recent Advances %U https://doi.org/10.1007/s40641-014-0001-3 1 %X In recent years, two major topics have emerged in regional climate modeling. One topic is the extension of regional climate models of the atmosphere to regional Earth system models. Specifically, the coupling of regional atmosphere-ocean models is an important step toward reducing the dependency of regional climate simulations on global models. The second topic is the decrease of the horizontal grid spacing such that convection can be explicitly computed. These topics present new challenges for the observational data used to evaluate the models. To date, gridded observation data on the kilometer scale have been only available over a few specific regions. The size of regional climate model ensembles has considerably increased in recent years. Thus, how to manage large datasets and how to select representative subsets are challenges that must be addressed. Comparatively, little progress has been achieved in the fields of boundary conditions and physical parameterizations. %0 journal article %@ 1463-5003 %A Stanev, E.V., Lu, X., Grashorn, S. %D 2015 %J Ocean Modelling %P 56-74 %R doi:10.1016/j.ocemod.2015.07.002 %T Physical processes in the transition zone between North Sea and Baltic Sea. Numerical simulations and observations %U https://doi.org/10.1016/j.ocemod.2015.07.002 %X The dynamics in the transition zone between the North Sea and Baltic Sea are analyzed here using data from a 22-year-long climatic simulation with a focus on the periods 1992–1994 and 2001–2003 when two recent major inflow events occurred. Observations from gauges and in situ measurements are used to validate the model. Parameters, which cannot be easily measured, such as water and salt transports through straits, have been compared against similar previous estimates. The good performance of simulations is attributed to the finer resolution of the model compared to earlier set ups. The outflow in the Kattegat, which is an analogue of the tidal outflows, tends to propagate to the North over the shallows without showing a substantial deflection to the right due to the Earth's rotation. The inflow follows the topography. The different inflow and outflow pathways are explained as a consequence of the specific combination of bathymetry, axial and lateral processes. The circulation in Kattegat is persistently clockwise with an eastern intensification during inflow and a western one during outflow regimes. The tidal wave there propagates as Kelvin wave, keeping the coast on its right. The flows in the two main straits reveal very different responses to tides, which are also highly asymmetric during inflow and outflow conditions. The circulation has a typical two-layer structure, the correlation between salinity and velocity tends to increase the salt transport in the salinity conveyor belt. The transversal circulation in the entrance of the Sound enhances the vertical mixing of the saltier North Sea water. The long-term averaged ratio of the water transports through the Great Belt and the Sound is ∼2.6-2.7 but this number changes reaching lower values during the major inflow in 1993. The transports in the straits are asymmetric. During inflow events the repartition of water penetrating the Baltic Sea is strongly in favor of the pathway through the Sound, which provides a shorter connection between the Kattegat and Baltic proper. The wider Great Belt has a relatively larger role in exporting water from the Baltic into the North Sea. A demonstration is given that the ventilation of the Baltic Sea deep water is not only governed by the dynamics in the straits and the strong westerly winds enhancing the eastward propagation of North Sea water (a case in 1993), but also by the clockwise circulation in the Kattegat acting as a preconditioning factor for the flow-partitioning. %0 journal article %@ 0280-6495 %A Bierstedt, S., Huenicke, B., Zorita, E. %D 2015 %J Tellus A %P 29073 %R doi:10.3402/tellusa.v67.29073 %T Variability of wind direction statistics of mean and extreme wind events over the Baltic Sea region %U https://doi.org/10.3402/tellusa.v67.29073 %X It is not clear to what extent the variations of seasonal mean winds and seasonal extreme winds are related. We investigate this relationship for the Baltic Sea area by analysing two regional climate gridded data sets, coastDat2 and HiResAFF, for the periods 1948–2009 and 1850–2009, respectively. Both data sets are based on regional climate simulations incorporating information from observations with the aim of reproducing the observed trajectory of climate variables. We compare the wind direction distribution of mean and extreme wind events by analysing seasonal wind roses. Mean wind directions display a more isotropic distribution, with a seasonally varying maximum. Extreme winds are much more constrained to south-westerly and westerly directions. The co-variability in time between the wind speed along the dominant directions of seasonal mean and the seasonal extreme winds was investigated using a complex correlation coefficient. This coefficient enables the simultaneous investigation of the co-variability of two-dimensional variables, for example wind. This coefficient is small for all seasons, indicating a very weak co-variance in time between seasonal mean and seasonal extremes. Hence, deviations in the direction of the mean wind are not a good indicator for deviations in the direction of extreme winds. We also assess the spatial structure and temporal variability of mean and extreme wind statistics using a principal component analysis. The principal components exhibit no significant long-term trends over the simulation periods, although multidecadal trends are detected for some periods and seasons. In recent decades, wintertime mean and extremes shifted to a more south-westerly direction. In the other seasons, no trends in wind directions are detected. We also investigate the possibility that seasonal patterns of extreme winds might persist over several adjacent seasons. No such persistent patterns can be identified, and hence extreme winds in one season are not useful to predict extreme winds in the following seasons. %0 journal article %@ 0003-0007 %A Rummukainen, M., Rockel, B., Baerring, L., Christensen, J.H., Reckermann, M. %D 2015 %J Bulletin of the American Meteorological Society %N 8 %P ES135-ES138 %R doi:10.1175/BAMS-D-14-00214.1 %T Twenty-First-Century Challenges in Regional Climate Modeling %U https://doi.org/10.1175/BAMS-D-14-00214.1 8 %X No abstract %0 journal article %@ 1462-9011 %A Doering, M., Ratter, B. %D 2015 %J Environmental Science & Policy %P 448-455 %R doi:10.1016/j.envsci.2015.08.009 %T Heimat’ as a boundary object? Exploring the potentialities of a boundary object to instigate productive science-stakeholder interaction in North Frisia (Germany) %U https://doi.org/10.1016/j.envsci.2015.08.009 %X The North Frisian Wadden Sea represents one of the best researched natural regions in the world. Since the end of the 1980s, scientific research has been carried out to scientifically study, analyse and assess this intertidal coastal zone under the conceptual umbrella of ecosystem research. The outcome of this assessment materialised in the establishment of the Nationalpark Schleswig-Holsteinisches Wattenmeer. Its implementation caused considerable conflicts between coastal inhabitants, national park authorities and government officials. Arguments in these disputes revolved around the validity and relevance of scientific knowledge generated to assess and legitimately protect the tidelands and areas of the Waddensea. In summary, the whole implementation process was locally perceived as a politically endorsed top-down enforcement strategy only allowing scientific knowledge for decision-making purposes while local concerns and ‘knowledges’ were not included. To learn from these developments and past mistakes, we compare concepts of co-management, boundary work and boundary objects (BO) to theoretically and methodologically explore their potentials to generate shared meanings and instigate communication in the context of future managing purposes. Against this theoretical background, we propose the empirical show-case example of the German concept of ‘Heimat’ as a BO to assess its applicability to study place-based meanings and to illustrate it as a practice-oriented point of entry to initiate productive science-stakeholder interaction (SSI) in managing the North Frisian Wadden Sea. %0 journal article %@ 1386-2588 %A Janssen, A.B.G., Arhonditsis, G.B., Beusen, A., Bolding, K., Bruce, L., Bruggeman, J., Couture, R.-M., Downing, A.S., Elliott, J.A., Frassl, M.A., Gal, G., Gerla, D.J., Hipsey, M.R., Hu, F., Ives, S.C., Janse, J.H., Jeppesen, E., Joehnk, K.D., Kneis, D., Kong, X., Kuiper, J.J., Lehmann, M.K., Lemmen, C., Oezkundakci, D., Petzoldt, T., Rinke, K., Robson, B.J., Sachse, R., Schep, S.A., Schmid, M., Scholten, H., Teurlincx, S., Trolle, D., Troost, T.A., Dam, A.A.van, Gerven, L.P.A.van, Weijerman, M., Scott A. Wells, S.A., Mooij, W.M. %D 2015 %J Aquatic Ecology %N 4 %P 513-548 %R doi:10.1007/s10452-015-9544-1 %T Exploring, exploiting and evolving diversity of aquatic ecosystem models: a community perspective %U https://doi.org/10.1007/s10452-015-9544-1 4 %X Here, we present a community perspective on how to explore, exploit and evolve the diversity in aquatic ecosystem models. These models play an important role in understanding the functioning of aquatic ecosystems, filling in observation gaps and developing effective strategies for water quality management. In this spirit, numerous models have been developed since the 1970s. We set off to explore model diversity by making an inventory among 42 aquatic ecosystem modellers, by categorizing the resulting set of models and by analysing them for diversity. We then focus on how to exploit model diversity by comparing and combining different aspects of existing models. Finally, we discuss how model diversity came about in the past and could evolve in the future. Throughout our study, we use analogies from biodiversity research to analyse and interpret model diversity. We recommend to make models publicly available through open-source policies, to standardize documentation and technical implementation of models, and to compare models through ensemble modelling and interdisciplinary approaches. We end with our perspective on how the field of aquatic ecosystem modelling might develop in the next 5–10 years. To strive for clarity and to improve readability for non-modellers, we include a glossary. %0 journal article %@ 1814-9324 %A Dallmeyer, A., Claussen, M., Fischer, N., Haberkorn, K., Wagner, S., Pfeiffer, M., Jin, L., Khon, V., Wang, Y., Herzschuh, U. %D 2015 %J Climate of the Past %N 2 %P 305-326 %R doi:10.5194/cp-11-305-2015 %T The evolution of sub-monsoon systems in the Afro-Asian monsoon region during the Holocene– comparison of different transient climate model simulations %U https://doi.org/10.5194/cp-11-305-2015 2 %X The recently proposed global monsoon hypothesis interprets monsoon systems as part of one global-scale atmospheric overturning circulation, implying a connection between the regional monsoon systems and an in-phase behaviour of all northern hemispheric monsoons on annual timescales (Trenberth et al., 2000). Whether this concept can be applied to past climates and variability on longer timescales is still under debate, because the monsoon systems exhibit different regional characteristics such as different seasonality (i.e. onset, peak and withdrawal). To investigate the interconnection of different monsoon systems during the pre-industrial Holocene, five transient global climate model simulations have been analysed with respect to the rainfall trend and variability in different sub-domains of the Afro-Asian monsoon region. Our analysis suggests that on millennial timescales with varying orbital forcing, the monsoons do not behave as a tightly connected global system. According to the models, the Indian and North African monsoons are coupled, showing similar rainfall trend and moderate correlation in centennial rainfall variability in all models. The East Asian monsoon changes independently during the Holocene. The dissimilarities in the seasonality of the monsoon sub-systems lead to a stronger response of the North African and Indian monsoon systems to the Holocene insolation forcing than of the East Asian monsoon and affect the seasonal distribution of Holocene rainfall variations. Within the Indian and North African monsoon domain, precipitation solely changes during the summer months, showing a decreasing Holocene precipitation trend. In the East Asian monsoon region, the precipitation signal is determined by an increasing precipitation trend during spring and a decreasing precipitation change during summer, partly balancing each other. A synthesis of reconstructions and the model results do not reveal an impact of the different seasonality on the timing of the Holocene rainfall optimum in the different sub-monsoon systems. Rather they indicate locally inhomogeneous rainfall changes and show that single palaeo-records should not be used to characterise the rainfall change and monsoon evolution for entire monsoon sub-systems. %0 journal article %@ 0964-5691 %A Gonzalez-Riancho, P., Gerkensmeier, B., Ratter, B.M.W., Gonzalez, M., Medina, R. %D 2015 %J Ocean and Coastal Management %P 44-60 %R doi:10.1016/j.ocecoaman.2015.05.004 %T Storm surge risk perception and resilience: A pilot study in the German North Sea coast %U https://doi.org/10.1016/j.ocecoaman.2015.05.004 %X Resilience is defined as the capacity of a community to organise itself before, during and after a dangerous/hazardous event in order to minimise the impacts. A conceptual framework is proposed to assess the resilience of a community by understanding and integrating the institutional, legal and social capacities to cope and recover from a natural hazardous event in order to minimize the impacts in the short-term and to adapt to the risk in the long-term. A survey-based method and a specific resilience questionnaire is proposed to explore the perception of stakeholders regarding the risk and emergency management processes as well as psychological and social factors conditioning individual and community preparedness. The method is applied in a pilot area (the Dithmarschen district in the German North Sea Coast) for its validation before applying it to the entire Wadden Sea region, the pilot results being presented in this work. Although some questions may need some type of adaptation to fit adequately to other study sites, the conceptual and methodological framework could be applied worldwide. The study area and its population are characterized by their continuous interaction with the ocean, with the continuous transformation and reclamation of land for agricultural and other purposes, the constant reshaping of the coastline and frequent coastal inundation by storm surge flooding. The assessment allows identifying the main characteristics of the study area in terms of stakeholders' risk perception, intention to prepare, individual and societal behavioural patterns, as well as their opinion regarding authorities' decision-making on emergency and risk management. It also addresses potential improvement in emergency and risk management in terms of multi-sector partnerships and additional adaptation measures for the area. The deficiencies and incoherencies between society's and administration's answers detected in the analysis point towards the challenges to deal with, in order to foster an adequate community preparedness and adaptation to storm surge risk. Some of the results that the proposed method permitted to obtain in the study area show (i) the need for a better information strategy to enhance society's awareness and preparedness; (ii) the respondents' current proactive behaviour and preference on participatory risk management options, despite fully participatory schemes are not yet set by the authorities; (iii) the need for awareness campaigns regarding the relevance and benefits of the integrated approach in potential partnerships, and (iv) the need for tailored and site-specific adaptation instruments and measures due to the current society's disagreement with some of the options currently provided. The results are useful to improve risk reduction initiatives by means of including society's opinions from the beginning of the management process. %0 journal article %@ 0094-8276 %A Mohr, S., Kunz, M., Geyer, B. %D 2015 %J Geophysical Research Letters %N 24 %P 10904-10912 %R doi:10.1002/2015GL067118 %T Hail potential in Europe based on a regional climate model hindcast %U https://doi.org/10.1002/2015GL067118 24 %X Due to the local-scale nature of hail and a lack of appropriate observation systems, comprehensive, reliable, and consistent information about hail frequency and intensity in Europe is not available. To overcome this constraint, we developed a logistic hail model that quantifies the potential of the atmosphere to form hailstorms. The model is based on a combination of appropriate hail-relevant meteorological parameters. This paper presents the application of an adjusted version of the logistic model with the objective being to estimate the hail potential across Europe based on dynamically downscaled National Centers for Environmental Prediction/National Center for Atmospheric Research1 reanalysis over a long-term period of 60 years (1951–2010). The model output, in terms of the potential hail index (PHI), identified several hot spots that are well known from other observational studies. Time series of the PHI over the 60 year period show a high correlation at different sites across Europe and high annual and multiannual variability, but no overall trend. %0 journal article %@ 0280-6495 %A Ho-Hagemann, H.T.M., Hagemann, S., Rockel, B. %D 2015 %J Tellus A %P 28661 %R doi:10.3402/tellusa.v67.28661 %T On the role of soil moisture in the generation of heavy rainfall during the Oder flood event in July 1997 %U https://doi.org/10.3402/tellusa.v67.28661 %X Soil moisture–atmosphere feedbacks play an important role in the regional climate over many regions worldwide, not only for the mean climate but also for extreme events. Several studies have shown that the extent and severity of droughts and heat waves can be significantly impacted by dry or wet soil moisture conditions. To date, the impact of soil moisture on heavy rainfall events has been less frequently investigated. Thus, we consider the role of soil moisture in the formation of heavy rainfall using the Oder flood event in July 1997 as an example. Here, we used the regional climate model CCLM as an uncoupled standalone model and the coupled COSTRICE system, where CCLM is coupled with an ocean and a sea ice model over the Baltic and North Sea regions. The results from climate simulations over Europe show that the coupled model can capture the second phase (18–20 July) of heavy rainfall that led to the Oder flood, while the uncoupled model does not. Sensitivity experiments demonstrate that the better performance of the coupled model can be attributed to the simulated soil moisture conditions in July 1997 in Central Europe, which were wetter for the coupled model than for the uncoupled model. This finding indicates that the soil moisture preceding the event significantly impacted the generation of heavy rainfall in this second phase. The better simulation in the coupled model also implies the added value that the atmosphere–ocean coupling has on the simulation of this specific extreme event. As none of the model versions captured the first phase (4–8 July), despite the differences in soil moisture, it can be concluded that the importance of soil moisture for the generation of heavy rainfall events strongly depends on the event and the general circulation pattern associated with it. %0 journal article %@ 0148-0227 %A Feng, J., Storch, H.v., Jiang, W., Weisse, R. %D 2015 %J Journal of Geophysical Research : Oceans %N 12 %P 8039-8051 %R doi:10.1002/2015JC011336 %T Assessing changes in extreme sea levels along the coast of China %U https://doi.org/10.1002/2015JC011336 12 %X Hourly tide-gauge data along the coast of China are used to evaluate changes in extreme water levels in the past several decades. Mean sea level, astronomical tide, nontidal component and the tide-surge interaction was analyzed separately to assess their roles in the changes of extreme sea levels. Mean sea level at five tide gauges, Kanmen, Keelung, Zhapo, Xiamen and Quarrybay, show significant increasing trends during the past decades (1954–2013) with a rate of about 1.4–3.5 mm/yr. At Keelung, Kaohsiung and Quarrybay the mean high waters increased during 1954–2013 with a rate from 0.6 to 1.8 mm/yr, while the annual mean tidal range rose at the same time by 0.9 to 3.8 mm/yr. In terms of storm surge intensities, there is interannual variability and decadal variability but five tide gauges show significant decreasing trends, and three gauges, at Keelung, Xiamen and Quarrybay, exhibited significant increases of extreme sea levels with trends of 1.5–6.0 mm/yr during 1954–2013. Significant tide-surge interactions were found at all 12 tide gauges, but no obvious change was found during the past few decades. The changes in extreme sea levels in this area are strongly related to the changes of mean sea levels (MSL). At gauges, where the tide-surge interaction is large, the astronomic tides are also an important factor for the extreme sea levels, whereas tide gauges with little tide-surge interaction, the changes of wind driven storm surge component adds to the change of the extreme sea levels. %0 journal article %@ 0280-6495 %A Childers, K.H., Flagg, C.N., Rossby, T., Schrum, C. %D 2015 %J Tellus A %P 28067 %R doi:10.3402/tellusa.v67.28067 %T Directly measured currents and estimated transport pathways of Atlantic Water between 59.5°N and the Iceland–Faroes–Scotland Ridge %U https://doi.org/10.3402/tellusa.v67.28067 %X Using vessel-mounted acoustic Doppler current profiler data from four different routes between Scotland, Iceland and Greenland, we map out the mean flow of water in the top 400 m of the northeastern North Atlantic. The poleward transport east of the Reykjanes Ridge (RR) decreases from ~8.5 to 10 Sv (1 Sverdrup=106 m3 s−1) at 59.5°N to 61°N to 6 Sv crossing the Iceland–Faroes–Scotland Ridge. The two longest ~1200 km transport integrals have 1.4–0.94 Sv uncertainty, respectively. The overall decrease in transport can in large measure be accounted for by a ~1.5 Sv flow across the RR into the Irminger Sea north of 59.5°N and by a ~0.5 Sv overflow of dense water along the Iceland–Faroes Ridge. A remaining 0.5 Sv flux divergence is at the edge of detectability, but if real could be accounted for through wintertime convection to >400 m and densification of upper ocean water. The topography of the Iceland Basin and the banks west of Scotland play a fundamental role in controlling flow pathways towards and past Iceland, the Faroes and Scotland. Most water flows north unimpeded through the Iceland Basin, some in the centre of the basin along the Maury Channel, and some along Hatton Bank, turning east along the northern slopes of George Bligh Bank, Lousy Bank and Bill Bailey’s Bank, whereupon the flow splits with ~3 Sv turning northwest towards the Iceland–Faroes Ridge and the remainder continuing east towards and north of the Wyville-Thomson Ridge (WTR) to the Scotland slope thereby increasing the Slope Current transport from ~1.5 Sv south of the WTR to 3.5 Sv in the Faroes–Shetland Channel. %0 journal article %@ 0948-4280 %A Fan, Y.-M., Guenther, H., Doong, D.-J., Kao, C.-C. %D 2015 %J Journal of Marine Science and Technology %P 943-950 %R doi:10.6119/JMST-015-0610-13 %T Improved Boundary Values of Ocean Wave Fields Using a Data Assimilation Scheme %U https://doi.org/10.6119/JMST-015-0610-13 %X The objective of this study was to assess the accuracy of numerical wave forecasts through data assimilation of boundary values. A sequential data assimilation scheme was adopted to utilise altimeter data. The performance of the system in terms of operational applications, specifically for typhoon waves, was investigated. Two typhoons that occurred in 2006 around Taiwan (Kaemi and Shanshan) were used as case studies. The proposed data assimilation increased the forecast accuracy of the boundary values in terms of the wave parameters, such as the wave heights and periods. The results showed that after the assimilation, the assimilation model was significantly improved, especially the peak value of the wave and time of occurrence of the peak value. %0 journal article %@ 1814-9324 %A Fernandez Donado, L., Gonzalez-Rouco, J.F., Garcia Bustamante, E., Goosse, H., Jungclaus, J., Bothe, O., Hegerl, G., Moberg, A., Raible, C.C., Schurer, A., Wagner, S., Zorita, E., Hind, A., Lehner, F., McKay, N., Warren, E., Widmann, M. %D 2015 %J Climate of the Past %N 12 %P 1673-1699 %R doi:10.5194/cp-11-1673-2015 %T Continental-scale temperature variability in PMIP3 simulations and PAGES 2k regional temperature reconstructions over the past millennium %U https://doi.org/10.5194/cp-11-1673-2015 12 %X Estimated external radiative forcings, model results, and proxy-based climate reconstructions have been used over the past several decades to improve our understanding of the mechanisms underlying observed climate variability and change over the past millennium. Here, the recent set of temperature reconstructions at the continental-scale generated by the PAGES 2k project and a collection of state-of-the-art model simulations driven by realistic external forcings are jointly analysed. The first aim is to estimate the consistency between model results and reconstructions for each continental-scale region over the time and frequency domains. Secondly, the links between regions are investigated to determine whether reconstructed global-scale covariability patterns are similar to those identified in model simulations. The third aim is to assess the role of external forcings in the observed temperature variations. From a large set of analyses, we conclude that models are in relatively good agreement with temperature reconstructions for Northern Hemisphere regions, particularly in the Arctic. This is likely due to the relatively large amplitude of the externally forced response across northern and high-latitude regions, which results in a clearly detectable signature in both reconstructions and simulations. Conversely, models disagree strongly with the reconstructions in the Southern Hemisphere. Furthermore, the simulations are more regionally coherent than the reconstructions, perhaps due to an underestimation of the magnitude of internal variability in models or to an overestimation of the response to the external forcing in the Southern Hemisphere. Part of the disagreement might also reflect large uncertainties in the reconstructions, specifically in some Southern Hemisphere regions, which are based on fewer palaeoclimate records than in the Northern Hemisphere. %0 journal article %@ 1814-9324 %A Gomez-Navarro, J.J., Bothe, O., Wagner, S., Zorita, E., Werner, J.P., Luterbacher, J., Raible, C.C., Montavez, J.P. %D 2015 %J Climate of the Past %N 8 %P 1077-1095 %R doi:10.5194/cp-11-1077-2015 %T A regional climate palaeosimulation for Europe in the period 1500–1990 – Part 2: Shortcomings and strengths of models and reconstructions %U https://doi.org/10.5194/cp-11-1077-2015 8 %X This study compares gridded European seasonal series of surface air temperature (SAT) and precipitation (PRE) reconstructions with a regional climate simulation over the period 1500–1990. The area is analysed separately for nine subareas that represent the majority of the climate diversity in the European sector. In their spatial structure, an overall good agreement is found between the reconstructed and simulated climate features across Europe, supporting consistency in both products. Systematic biases between both data sets can be explained by a priori known deficiencies in the simulation. Simulations and reconstructions, however, largely differ in the temporal evolution of past climate for European subregions. In particular, the simulated anomalies during the Maunder and Dalton minima show stronger response to changes in the external forcings than recorded in the reconstructions. Although this disagreement is to some extent expected given the prominent role of internal variability in the evolution of regional temperature and precipitation, a certain degree of agreement is a priori expected in variables directly affected by external forcings. In this sense, the inability of the model to reproduce a warm period similar to that recorded for the winters during the first decades of the 18th century in the reconstructions is indicative of fundamental limitations in the simulation that preclude reproducing exceptionally anomalous conditions. Despite these limitations, the simulated climate is a physically consistent data set, which can be used as a benchmark to analyse the consistency and limitations of gridded reconstructions of different variables. A comparison of the leading modes of SAT and PRE variability indicates that reconstructions are too simplistic, especially for precipitation, which is associated with the linear statistical techniques used to generate the reconstructions. The analysis of the co-variability between sea level pressure (SLP) and SAT and PRE in the simulation yields a result which resembles the canonical co-variability recorded in the observations for the 20th century. However, the same analysis for reconstructions exhibits anomalously low correlations, which points towards a lack of dynamical consistency between independent reconstructions. %0 journal article %@ 0167-6105 %A Geyer, B., Weisse, R., Bisling, P., Winterfeldt, J. %D 2015 %J Journal of Wind Engineering and Industrial Aerodynamics %P 18-29 %R doi:10.1016/j.jweia.2015.09.005 %T Climatology of North Sea wind energy derived from a model hindcast for 1958-2012 %U https://doi.org/10.1016/j.jweia.2015.09.005 %X The inter-annual to decadal variability can reach up to 5% from the multi-decadal mean and therefore plays an important role in wind energy; wind power estimates based on short observational time series, particularly from the late 1990s, may exhibit high biases. The up-scaling from wind speeds at a height of 10 m using conventional power laws may result in similar biases. On inter-annual to decadal time scales, synergies are not expected from the different arrays in the North Sea, i.e., a decrease in the power output of an array may not be balanced by another. %0 journal article %@ 0003-0007 %A Feser, F., Barcikowska, M., Haeseler, S., Lefebvre, C., Schubert-Frisius, M., Stendel, M., Storch, H.v., Zahn, M. %D 2015 %J Bulletin of the American Meteorological Society %N 12 %P S 51-S 55 %R doi:10.1175/BAMS-EEE_2014_ch11.1 %T Hurricane Gonzalo and its extratropical transition to a strong European storm %U https://doi.org/10.1175/BAMS-EEE_2014_ch11.1 12 %X exceptional strength over Europe; however, it was within the historical range of such transforming storms. %0 journal article %@ 0930-7575 %A Lange, S., Rockel, B., Volkholz, J., Bookhagen, B. %D 2015 %J Climate Dynamics %N 9-10 %P 2839-2857 %R doi:10.1007/s00382-014-2199-0 %T Regional climate model sensitivities to parametrizations of convection and non-precipitating subgrid-scale clouds over South America %U https://doi.org/10.1007/s00382-014-2199-0 9-10 %X This study provides a first thorough evaluation of the COnsortium for Small scale MOdeling weather prediction model in CLimate Mode (COSMO-CLM) over South America. Simulations are driven by ERA-Interim reanalysis data. Besides precipitation, we examine the surface radiation budget, cloud cover, 2 m temperatures, and the low level circulation. We evaluate against reanalysis data as well as observations from ground stations and satellites. Our analysis focuses on the sensitivity of results to the convective parametrization in comparison to their sensitivity to the representation of non-precipitating subgrid-scale clouds in the parametrization of radiation. Specifically, we compare simulations with a relative humidity versus a statistical subgrid-scale cloud scheme, in combination with convection schemes according to Tiedtke (Mon Weather Rev 117(8):1779–1800, 1989) and from the European Centre for Medium-Range Weather Forecasts Integrated Forecasting System (IFS) cycle 33r1. The sensitivity of simulated tropical precipitation to the parametrizations of convection and subgrid-scale clouds is of similar magnitude. We show that model runs with different subgrid-scale cloud schemes produce substantially different cloud ice and liquid water contents. This impacts surface radiation budgets, and in turn convection and precipitation. Considering all evaluated variables in synopsis, the model performs best with the (both non-default) IFS and statistical schemes for convection and subgrid-scale clouds, respectively. Despite several remaining deficiencies, such as a poor simulation of the diurnal cycle of precipitation or a substantial austral summer warm bias in northern Argentina, this new setup considerably reduces long-standing model biases, which have been a feature of COSMO-CLM across tropical domains. %0 journal article %@ 1408-967X %A Lemmen, C. %D 2015 %J Documenta Praehistorica %P 93-102 %R doi:10.4312\dp.42.5 %T Cultural and demic diffusion of first farmers, herders, and their innovations across Eurasia %U https://doi.org/10.4312\dp.42.5 %X and not from a time-integrated perspective. %0 journal article %@ 1616-7341 %A Grayek, S., Stanev, E.V., Schulz-Stellenfleth, J. %D 2015 %J Ocean Dynamics %N 12 %P 1665-1684 %R doi:10.1007/s10236-015-0889-8 %T Assessment of the Black Sea observing system. A focus on 2005-2012 Argo campaigns %U https://doi.org/10.1007/s10236-015-0889-8 12 %X An observing system in the Black Sea combining remote sensing data such as sea level anomalies from altimetry, sea surface temperature from satellite radiometer and data from Argo floats has been analyzed with the aim to quantify the contribution of different information sources when reconstructing the ocean state. The main research questions are: (1) do Argo float measurements substantially impact the quality of estimates, (2) what is the dependence of this quality upon the data and sampling used, and (3) are there specific Black Sea issues? Numerical model output and statistical analysis were used for this purpose. It has been demonstrated that the statistical method performs in a consistent way reproducing known geophysical patterns. Maximum footprints of sea level, salinity and temperature were illustrated, most of them clearly connected with specific thermohaline conditions and the general circulation. Reduced analysis capabilities were identified as associated with a low level of dynamical coupling between the shelf and the open ocean, mesoscale dynamics and representation of diapycnic processes in the models. The accuracy of Argo pressure measurements appeared very important to resolve the extremely sharp stratification in the upper layers. The present-day number of Argo floats operating in the Black Sea of about 10, seems optimal for operational purposes. %0 journal article %@ 0142-7873 %A Smith, S.L., Merico, A., Wirtz, K.W., Pahlow, M. %D 2014 %J Journal of Plankton Research %N 3 %P 613-620 %R doi:10.1093/plankt/fbu011 %T Leaving misleading legacies behind in plankton ecosystem modelling %U https://doi.org/10.1093/plankt/fbu011 3 %X The value of mechanistic ecosystem modelling has long been appreciated, and in connection with trait-based approaches it has recently stimulated a more process-based understanding of adaptive capacities and trade-offs. Notwithstanding recent advances, even sophisticated state-of-the-art models of plankton ecosystems, some of which include hundreds of idealized species, do not accurately represent the great biodiversity of plankton, or the associated flexible adaptive response of plankton communities. We build on previous reviews to suggest that it may be necessary to discard some common assumptions and try new approaches in order to construct models that can make new and testable predictions about the “adaptive capacity” of plankton ecosystems. Major challenges remain unresolved for modelling interacting communities of producers and consumers. Rather than the common approach of mixing and matching existing model components, each laden with its own legacy assumptions, we suggest that a judicious combination of innovative, mechanistic approaches that combine traits and trade-offs will likely better address such challenges. %0 journal article %@ 1436-3798 %A Kannen, A. %D 2014 %J Regional Environmental Change %N 6 %P 2139-2150 %R doi:10.1007/s10113-012-0349-7 %T Challenges for marine spatial planning in the context of multiple sea uses, policy arenas and actors based on experiences from the German North Sea %U https://doi.org/10.1007/s10113-012-0349-7 6 %X Today, increasing use intensity and establishment of new sea uses such as offshore wind farming can be observed in coastal and marine waters. This development also increases the pressure on coastal and marine ecosystems. The exclusive economic zone of the German North Sea can serve as an example for this development, in particular illustrating the need to combine multiple uses and societal demands within a given sea area. In order to deal with the resulting conflicts and cumulative impacts, new planning tools and integrated approaches to planning and management are developing. While the sea becomes a contested but at the same time politically recognised area, also conflicts rooted in different perceptions, values and attitudes of coastal people can be observed. In order to deal with the current challenges in marine areas, marine spatial planning and similar tools for integrated planning need to be developed in the form of communication processes, which link diverse sets of information and span a dialogue between groups of society and across spatial scales including the transnational dimension. %0 journal article %@ 1616-7341 %A Albrecht, F., Weisse, R. %D 2014 %J Ocean Dynamics %N 5 %P 633-642 %R doi:10.1007/s10236-014-0708-7 %T Pressure effects on regional mean sea level trends in the German Bight in the twenty-first century %U https://doi.org/10.1007/s10236-014-0708-7 5 %X The effect of large-scale atmospheric pressure changes on regional mean sea level projections in the German Bight in the twenty-first century are considered. A developed statistical model is applied to climate model data of sea level pressure for the twenty-first century to assess the potential contribution of large-scale atmospheric changes to future sea level changes in the German Bight. Using 78 experiments, an ensemble mean of 1.4-cm rise in regional mean sea level is estimated until the end of the twenty-first century. Changes are somewhat higher for realisations of the special report on emission scenarios (SRES) A1B and A2, but generally do not exceed a few centimeters. This is considerably smaller than the changes expected from steric and self-gravitational effects. Large-scale changes in sea level pressure are thus not expected to provide a substantial contribution to twenty-first century sea level changes in the German Bight. %0 journal article %@ 0930-7575 %A Cavicchia, L., Storch, H.v., Gualdi, S. %D 2014 %J Climate Dynamics %N 5-6 %P 1183-1195 %R doi:10.1007/s00382-013-1893-7 %T A long-term climatology of medicanes %U https://doi.org/10.1007/s00382-013-1893-7 5-6 %X Medicanes, intense and destructive mesoscale cyclones exhibiting several similarities with tropical hurricanes, are known to struck occasionally the Mediterranean Sea. Thanks to a high-resolution dynamical downscaling effort, we are able to study for the first time the long-term climatology of those rare storms in a systematic way. The distribution of medicanes frequency in space and time is discussed, and the environmental factors responsible for their formation are investigated. We find that medicanes develop in those areas of the Mediterranean region where intrusions of cold air in the upper troposphere can produce configurations of thermodynamical disequilibrium of the atmosphere similar to those associated with the formation of tropical cyclones. %0 journal article %@ 1866-3508 %A Geyer, B. %D 2014 %J Earth System Science Data %N 1 %P 147-164 %R doi:10.5194/essd-6-147-2014 %T High-resolution atmospheric reconstruction for Europe 1948–2012: coastDat2 %U https://doi.org/10.5194/essd-6-147-2014 1 %X The coastDat data sets were produced to give a consistent and homogeneous database mainly for assessing weather statistics and climate changes since 1948, e.g., in frequencies of extremes for Europe, especially in data sparse regions. A sequence of numerical models was employed to reconstruct all aspects of marine climate (such as storms, waves, surges, etc.) over many decades. The acronym coastDat stands for the set of consistent ocean and atmospheric data, where the atmospheric data where used as forcing for the reconstruction of the sea state. Here, we describe the atmospheric part of coastDat2 (Geyer and Rockel, 2013; doi:10.1594/WDCC/coastDat-2_COSMO-CLM). It consists of a regional climate reconstruction for the entire European continent, including the Baltic Sea and North Sea and parts of the Atlantic. The simulation was done for 1948 to 2012 with the regional climate model COSMO-CLM (CCLM) and a horizontal grid size of 0.22 degree in rotated coordinates. Global reanalysis data of NCEP1 were used as forcing and spectral nudging was applied. To meet the demands on the coastDat data set about 70 variables are stored hourly. %0 journal article %@ 0924-7963 %A Zhang, W., Harff, J., Schneider, R., Meyer, M., Zorita, E., Huenicke, B. %D 2014 %J Journal of Marine Systems %P 4-18 %R doi:10.1016/j.jmarsys.2013.06.003 %T Holocene morphogenesis at the southern Baltic Sea: Simulation of multi-scale processes and their interactions for the DarssZingst peninsula %U https://doi.org/10.1016/j.jmarsys.2013.06.003 %X A modeling methodology based on a multi-scale hybrid morphodynamic model and representative climatic driving conditions is presented to study the long-term morphological evolution of wave-dominated coasts on a centennial-to-millennial scale. The Darss–Zingst peninsula at the southern Baltic Sea, which developed during the last 6000 years by a combined effect of eustatic sea level change, isostatic movement, meteorological drivers and nearshore sediment dynamics, is selected for a case study. A paleo-Digital Elevation Model (DEM) serving as initial condition is reconstructed by a compilation of recent digital elevation data sets, an eustatic sea-level curve, an isostatic map and dated sediment cores. Representative wind series are generated based on a statistical analysis of paleo-wind data from a simulation with the coupled atmosphere-ocean general circulation model ECHO-G over the last 7000 cal yr. These wind data were calibrated by proxies from lithostratigraphic studies of sediment cores from the central Baltic Sea, and used as climate driving conditions for the morphodynamic model. Based on the reconstructed paleo-DEM and the representative climatic driving conditions, the methodology is applied to reconstruct the Holocene morphogenesis of the Darss–Zingst peninsula since 6000 cal yr BP. Simulation results indicate that the development of the barrier system is a combination of long-term effects of climate change, isostatic crustal movement, wave dynamics and eolian transport with short-term effects of extreme wind events, i.e. storms. %0 journal article %@ 1563-0110 %A Lemmen, C. %D 2014 %J Archaeology, Ethnography and Anthropology of Eurasia %N 3 %P 48-58 %R doi:10.1016/j.aeae.2014.03.007 %T Mechanisms shaping the transition to farming in Europe and the North American Woodland %U https://doi.org/10.1016/j.aeae.2014.03.007 3 %X Despite the fact that Europe and Eastern North America both have similar woodland environments, the emergence of agriculture in these areas proceeded very differently varying in timing, speed, and mechanism. To analyze the different subsistence paths the Global Land Use and Technological Evolution Simulator was used, a numerical model for simulating demography, innovation, domestication, migration and trade within the geoenvironmental context. I demonstrate how Europe receives a large package of foreign domesticates and converts rapidly. In contrast, trajectories relating to Eastern North America exhibit a gradual transition in which hunting and gathering and agropastoralism coexist for a long period of time, and agriculture is integrated slowly into the existing subsistence scheme. I deduce from this a qualitative economic difference in the two regional transitions: limited population size in Europe, limited resources in Eastern North America. %0 journal article %@ 0894-8755 %A Dangendorf, S., Mueller-Navarra, S., Jensen, J., Schenk, F., Wahl, T., Weisse, R. %D 2014 %J Journal of Climate %N 10 %P 3582-3595 %R doi:10.1175/JCLI-D-13-00427.1 %T North Sea storminess from a novel storm surge record since AD 1843 %U https://doi.org/10.1175/JCLI-D-13-00427.1 10 %X The detection of potential long-term changes in historical storm statistics and storm surges plays a vitally important role for protecting coastal communities. In the absence of long homogeneous wind records, we present a novel, independent and homogeneous storm surge record based on water level observations in the North Sea since AD 1843. Storm surges are characterized by considerable inter-annual to decadal variability linked to large-scale atmospheric circulation patterns. Time periods of increased storm surge levels prevailed in the late 19th and 20th centuries without any evidence for significant long-term trends. This contradicts with recent findings based on reanalysis data, which suggest increasing storminess in the region since the late 19th century. We compare the wind and pressure fields from the 20th century reanalysis (20CRv2) with the storm surge record by applying state of the art empirical wind surge formulas. The comparison reveals that the reanalysis is a valuable tool which leads to good results over the past 100 years; previously the statistical relationship fails, leaving significantly lower values in the upper percentiles of the predicted surge time series. These low values lead to significant upward trends over the entire investigation period, which are in turn neither supported by the storm surge record nor by an independent circulation index based on homogeneous pressure readings. We therefore suggest that these differences are related to higher uncertainties in the earlier years of the 20CRv2 over the North Sea region. %0 journal article %@ 0301-4215 %A Kerr, S., Watts, L., Colton, J., Conway, F., Hull, A., Johnson, K., Jude, S., Kannen, A., MacDougall, S., McLachlan, C., Potts, T., Vergunst, J. %D 2014 %J Energy Policy %P 694-702 %R doi:10.1016/j.enpol.2013.11.063 %T Establishing an agenda for social studies research in marine renewable energy %U https://doi.org/10.1016/j.enpol.2013.11.063 %X To date, academic research relating to Marine Renewable Energy (MRE) has largely focused on resource assessment, technical viability and environmental impact. Experiences from onshore renewable energy tell us that social acceptability is equally critical to project success. However, the specific nature of the marine environment, patterns of resource distribution and governance means experiences from onshore may not be directly applicable to MRE and the marine environment. This paper sets out an agenda for social studies research linked to MRE, identifying key topics for future research: (i) economic impacts; (ii) wealth distribution and community benefits; (iii) communication and knowledge flow; (iv) consultation processes; (v) dealing with uncertainty; (vi) public attitudes; and (vii) planning processes. This agenda is based on the findings of the first workshop of ISSMER, an international research network of social scientists with interests in marine renewable energy. Importantly, this research agenda has been informed by the experiences of developers, regulators and community groups in Orkney. The Orkney archipelago, off the north coast of Scotland, is home to the most intense cluster of MRE research, development and deployment activity in the world today. %0 journal article %@ 0378-3839 %A Monbaliu, J., Chen, Z., Felts, D., Ge, J., Hissel, F., Kappenberg, J., Narayan, S., Nicholls, R.J., Ohle, N., Schuster, D., Sothmann, J., Willems, P. %D 2014 %J Coastal Engineering %P 32-49 %R doi:10.1016/j.coastaleng.2014.01.001 %T Risk assessment of estuaries under climate change: Lessons from Western Europe %U https://doi.org/10.1016/j.coastaleng.2014.01.001 %X The traditional SPR approach with a consecutive treatment of the flood, pathway and receptor is well understood and is widely used in coastal flood risk analysis. Here an enhanced 2D conceptual version of the SPR method is used to better describe the system and to allow flexibility in considering multiple scales, flood sources and pathways. The new approach is demonstrated by three estuarine case studies in western Europe: the Gironde estuary, France; the Dendermonde region in the Scheldt estuary, Belgium; and HafenCity (Hamburg) in the Elbe estuary, Germany. They differ considerably in the surface area considered, in the type of flood sources, and hence also in the SPR configuration. After a brief introduction of the typical characteristics of the three study sites including some lessons learned from past flood protection measures, the differences in application and results of the SPR approach are discussed. Emphasis is on the specific aspects for each study site, but embedded in a generic SPR framework. The resulting generic lessons learned about the flood sources and how this shapes subsequent analysis are transferable to numerous important estuaries worldwide. %0 journal article %@ 1616-7341 %A Groll, N., Grabemann, I., Gaslikova, L. %D 2014 %J Ocean Dynamics %N 1 %P 1-12 %R doi:10.1007/s10236-013-0666-5 %T North Sea wave conditions: an analysis of four transient future climate realizations %U https://doi.org/10.1007/s10236-013-0666-5 1 %X The multi-decadal wave conditions in the North Sea can be influenced by anthropogenic climate change. That may lead to the intensification of wave extremes in the future and consequently increase risks for the coastal areas as well as for on- and offshore human activities. Potential changes caused by alteration of atmospheric patterns are investigated. Four transient climate projections (1961–2100), reflecting two IPCC emission scenarios (A1B and B1) and two different initial states, are used to simulate the wave scenarios. The potential wind-induced changes in waves are studied by comparing future statistics (2001–2100) with the corresponding reference conditions (1961–2000). Generally, there is a small increase in future 99th percentile significant wave height for most eastern parts of the North Sea towards the end of the twenty-first century. This small increase is superimposed by a strong variability of the annual extremes on time scales of decades. Opposite to the differences in wave height, the change in wave direction to more waves propagating east shows less decadal variability and is more uniform among all realizations. Nevertheless, temporal and spatial differences of the wave height in the four climate projections point to the uncertainties in the climate change signals. %0 journal article %@ 0930-7575 %A Krueger, O., Feser, F., Baerring, L., Kaas, E., Schmith, T., Tuomenvirta, H., Storch, H.v. %D 2014 %J Climate Dynamics %N 3-4 %P 1127-1128 %R doi:10.1007/s00382-013-1814-9 %T Comment on "Trends and low frequency variability of extratropical cyclone activity in the ensemble of twentieth century reanalysis" by Xiaolan L. Wang, Y. Feng, G. P. Compo, V. R. Swail, F. W. Zwiers, R. J. Allan, and P. D. Sardeshmukh, Climate Dynamics, 2012 %U https://doi.org/10.1007/s00382-013-1814-9 3-4 %X 20CR estimates would be consistent with storminess derived from pressure-based proxies does not hold for the time prior to 1950. %0 journal article %@ 2095-0195 %A Li, M., Ge, J., Kappenberg, J., Much, D., Nino, O., Chen, Z. %D 2014 %J Frontiers of Earth Science %N 2 %P 181-189 %R doi:10.1007/s11707-013-0418-3 %T Morphodynamic processes of the Elbe River estuary, Germany: the Coriolis effect, tidal asymmetry and human dredging %U https://doi.org/10.1007/s11707-013-0418-3 2 %X The Digital Elevation Model (DEM) based on the historical sea-charts and on-site hydrological records were used to examine the morphological change of the Elbe River estuary. The results show that siltation predominated in the tidal flat in the northern estuary, with a net siltation rate of 1.8 cm·a−1 during 1927–2006. In contrast, a continuous erosion prevailed in the main river channel, south of the estuary, with a net erosion rate of 2.5 cm·a−1 in the same time. In addition, a seaward shift of the estuarine island has happened with the old island coalescing to the northern tidal flat and new one emerging through siltation process. The tidal asymmetry via ebbing flow (maximum at 140 cm·s−1, and average at 76 cm·s−1) prevailed in the tidal flat, meaning continuous aggradation northwestward, while flooding flow (maximum at 100 cm ·s−1, and average at 67 cm·s−1) dominated in the main river channel with deepening thaweg at south, showing a landward sedimentation via the tidal pumping processes. This dextral extension of the estuarine morphology is due to the Coriolis force, leading to the inconsistent directions of in-out flows, which enables to facilitate the estuarine siltation. Human dredging prevailing in the estuary has dramatically altered the nature of the silted river channel to erosional since the last century. This is characterized by a net erosion rate of 3.2 cm·a−1 derived from the DEMs mapping, but only partially accounting for the dredging amount of 1994–2006, when the total dredging volume was 67 × 106 m3, equal to 5.9 cm·a−1. %0 journal article %@ 0378-3839 %A Weisse, R., Bellafiore, D., Menendez, M., Mendez, F., Nicholls, R.J., Umgiesser, G., Willems, P. %D 2014 %J Coastal Engineering %P 4-14 %R doi:10.1016/j.coastaleng.2013.10.017 %T Changing extreme sea levels along European coasts %U https://doi.org/10.1016/j.coastaleng.2013.10.017 %X Extreme sea levels at European coasts and their changes over the twentieth and twenty-first centuries are considered, including a method to analyze extreme sea levels and to assess their changes in a consistent way at different sites. The approach is based on using a combination of statistical tools and dynamical modelling as well as observational data and scenarios for potential future developments. The analysis is made for both time series of extreme sea levels and individually for the different components contributing to the extremes comprising (i) mean sea level changes, (ii) wind waves and storm surges and (iii), for relevant places, river flows. It is found that while regionally results vary in detail, some general inferences can be obtained. In particular it is found, that extreme sea levels show pronounced short-term and long-term variability partly associated with seasonal and nodal tidal cycles. Long-term trends are mostly associated with corresponding mean sea level changes while changes in wave and storm surge climate mostly contribute to inter-annual and decadal variability, but do not show substantial long-term trends. It is expected that this situation will continue for the upcoming decades and that long-term variability dominates over long-term trends at least for the coming decades. %0 journal article %@ 0016-7460 %A Ratter, B.M.W., Philipp, K.H.I., Weig, B. %D 2014 %J Geographische Rundschau %N 3 %P 22-28 %T Heimat Kueste - Wahrnehmung durch die Bevoelkerung und nachhaltige Regionalentwicklung an Nordseekueste und Tideelbe %U 3 %X Das Wissen um die Wahrnehmung und Einschätzung der Bewohner kann als Ausgangsvariable für eine planerisch-strategische Gestaltung der zukünftigen Entwicklung der Küstenregion betrachtet werden. Sie ist Grundlage für Entwicklungsstrategien und gleichzeitig eine Basis, um Selbstverantwortung und Kooperation in der Bevölkerung zu aktivieren. %0 journal article %@ 0305-4403 %A Lemmen, C., Wirtz, K.W. %D 2014 %J Journal of Archaeological Science %P 65-72 %R doi:10.1016/j.jas.2012.10.023 %T On the sensitivity of the simulated European Neolithic transition to climate extremes %U https://doi.org/10.1016/j.jas.2012.10.023 %X of regional Neolithic transitions. Our study shows that the consideration of climate events improves the simulation of typical lags between cultural complexes, but that the overall difference to a model without climate events is not significant. Climate events may not have been as important for early sociocultural dynamics as endogenous factors. %0 journal article %@ 1726-4170 %A Stanev, E.V., He, Y., Staneva, J., Yakushev, E. %D 2014 %J Biogeosciences %N 20 %P 5707-5732 %R doi:10.5194/bg-11-5707-2014 %T Mixing in the Black Sea detected from the temporal and spatial variability of oxygen and sulfide – Argo float observations and numerical modelling %U https://doi.org/10.5194/bg-11-5707-2014 20 %X The temporal and spatial variability of the upper ocean hydrochemistry in the Black Sea is analysed using data originating from profiling floats with oxygen sensors and carried out with a coupled three-dimensional circulation-biogeochemical model including 24 biochemical state variables. Major focus is on the dynamics of suboxic zone which is the interface separating oxygenated and anoxic waters. The scatter of oxygen data seen when plotted in density coordinates is larger than those for temperature, salinity and passive tracers. This scatter is indicative of vigorous biogeochemical reactions in the suboxic zone, which acts as a boundary layer or internal sink for oxygen. This internal sink affects the mixing patterns of oxygen compared to the ones of conservative tracers. Two different regimes of ventilation of pycnocline were clearly identified: a gyre-dominated (cyclonic) regime in winter and a coastal boundary layer (anticyclonic eddy)-dominated regime in summer. These contrasting states are characterized by very different pathways of oxygen intrusions along the isopycnals and vertical oxygen conveyor belt organized in multiple-layered cells formed in each gyre. The contribution of the three-dimensional modelling to the understanding of the Black Sea hydro-chemistry, and in particular the coast-to-open-sea mixing, is also demonstrated. Evidence is given that the formation of oxic waters and of cold intermediate waters, although triggered by the same physical process, each follow a different evolution. The difference in the depths of the temperature minimum and the oxygen maximum indicates that the variability of oxygen is not only just a response to physical forcing and changes in the surface conditions, but undergoes its own evolution. %0 journal article %@ 1616-7341 %A Stanev, E.V., Al-Nadhairi, R., Staneva, J., Schulz-Stellenfleth, J., Valle-Levinson, A. %D 2014 %J Ocean Dynamics %N 7 %P 951-968 %R doi:10.1007/s10236-014-0733-6 %T Tidal wave transformations in the German Bight %U https://doi.org/10.1007/s10236-014-0733-6 7 %X Mesoscale and submesoscale dynamics associated with tidal wave transformations were addressed in the German Bight using numerical simulations. Tidal gauge and velocity observations in several locations were used to validate the numerical model. A downscaling approach included analysis of simulations with horizontal resolutions of 1, 0.4, and 0.2 km. It was shown that the modified tidal wave lost most of its energy after reflection or refraction over the eastern part of the German Bight. Energy loss resulted in a pronounced change of the wave’s spectral composition and generation of overtides. Tidal oscillations were modified by mesoscale processes associated with bathymetric channels. Semidiurnal and quarterdiurnal tides revealed very different spatial patterns. The former were aligned with the bathymetric channels, while the latter were rather “patchy” and had about half the spatial scales. In numerous areas around the bathymetric channels, the major axis of the M4 ellipses was normal or at some angle with the major axis of the M2 ellipses. Thus, higher harmonics developed “orthogonal” patterns that drove secondary circulations. Moreover, the ratio between spring and neap tidal amplitudes was relatively low in the Wadden Sea, showing reduced sensitivity of this very shallow area to fortnightly tidal variations. It was demonstrated that simulated hydrodynamics patterns help explain the physical mechanism shaping the median grain size distribution in the German Bight. %0 journal article %@ 0452-7739 %A Koesters, F., Grabemann, I., Schubert, R. %D 2014 %J Die Kueste %P 393-408 %T On SPM dynamiks in the turbidity maximum zone of the Weser estuary %U %X In der Trübungszone eines Ästuars schwanken die hohen Schwebstoffkonzentrationen auf unterschiedlichen Zeitskalen. Da mit der hohen Schwebstoffkonzentration auch hohe Sedimentationsraten und eine Verschlickung von Hafenanlagen verbunden sein können, ist ein umfassendes Systemverständnis zur Optimierung des Sedimentmanagements not-wendig. Auf der Basis von zurückliegenden Messkampagnen und Daten aus Dauermes-sungen wird die Variabilität der Trübungszone auf intratidalen Zeitskalen, dem Spring-Nipp-Zyklus und verbunden mit Änderungen des Oberwasserabflusses (saisonale Zeit-skala) untersucht und mit Modellergebnissen verglichen. Vorhergehende Ergebnisse, die die intratidale Variabilität als zyklischen Prozess aus Advektion suspendierten Materials, Deposition und Resuspension beschreiben, werden auf Basis der aktuellen Ergebnisse bestätigt. Eine starke Kopplung von Brackwasserzone und Trübungszone ist nicht nur auf der intratidalen Zeitskala sichtbar, sondern auch auf längeren Zeitskalen als Reaktion auf geänderte Oberwasserabflüsse. Der Spring-Nipp-Zyklus zeigt sich in den Schweb-stoffkonzentrationen, die bei Springtide deutlich größer sind als bei Nipptide, und gering-fügig in der Ausdehnung der Trübungszone. %0 journal article %@ 1814-9324 %A Strandberg, G., Kjellstroem, E., Poska, A., Wagner, S., Gaillard, M.-J., Trondman, A.-K., Mauri, A., Davis, B.A.S., Kaplan, J.O., Birks, H.J.B., Bjune, A.E., Fyfe, R., Giesecke, T., Kalnina, L., Kangur, M., Knaap, W.O.van der, Kokfelt, U., Kunes, P. %A , Latalowa, M., Marquer, L., Mazier, F., Nielsen, A.B., Smith, B., Seppae, H., Sugita, S. %D 2014 %J Climate of the Past %N 2 %P 661-680 %R doi:10.5194/cp-10-661-2014 %T Regional climate model simulations for Europe at 6 and 0.2 k BP: sensitivity to changes in anthropogenic deforestation %U https://doi.org/10.5194/cp-10-661-2014 2 %X This study aims to evaluate the direct effects of anthropogenic deforestation on simulated climate at two contrasting periods in the Holocene, ~6 and ~0.2 k BP in Europe. We apply We apply the Rossby Centre regional climate model RCA3, a regional climate model with 50 km spatial resolution, for both time periods, considering three alternative descriptions of the past vegetation: (i) potential natural vegetation (V) simulated by the dynamic vegetation model LPJ-GUESS, (ii) potential vegetation with anthropogenic land use (deforestation) from the HYDE3.1 (History Database of the Global Environment) scenario (V + H3.1), and (iii) potential vegetation with anthropogenic land use from the KK10 scenario (V + KK10). The climate model results show that the simulated effects of deforestation depend on both local/regional climate and vegetation characteristics. At ~6 k BP the extent of simulated deforestation in Europe is generally small, but there are areas where deforestation is large enough to produce significant differences in summer temperatures of 0.5–1 °C. At ~0.2 k BP, extensive deforestation, particularly according to the KK10 model, leads to significant temperature differences in large parts of Europe in both winter and summer. In winter, deforestation leads to lower temperatures because of the differences in albedo between forested and unforested areas, particularly in the snow-covered regions. In summer, deforestation leads to higher temperatures in central and eastern Europe because evapotranspiration from unforested areas is lower than from forests. Summer evaporation is already limited in the southernmost parts of Europe under potential vegetation conditions and, therefore, cannot become much lower. Accordingly, the albedo effect dominates in southern Europe also in summer, which implies that deforestation causes a decrease in temperatures. Differences in summer temperature due to deforestation range from −1 °C in south-western Europe to +1 °C in eastern Europe. The choice of anthropogenic land-cover scenario has a significant influence on the simulated climate, but uncertainties in palaeoclimate proxy data for the two time periods do not allow for a definitive discrimination among climate model results. %0 journal article %@ 0171-8630 %A Wirtz, K.W. %D 2014 %J Marine Ecology - Progress Series %P 81-94 %R doi:10.3354/meps10894 %T A biomechanical and optimality-based derivation of prey-size dependencies in planktonic prey selection and ingestion rates %U https://doi.org/10.3354/meps10894 %X In their natural environment, planktonic grazers encounter considerable size variation in prey species. As a quantitative representation of feeding on diverse prey, theoretical studies use feeding kernels to describe grazing intensity as a function of body size, a factor that is a strongly discriminative property of prey. However, kernel functions are in general based on heuristic and poorly tested choices, lack an unequivocal definition, and are often based on experiments using mono-specific prey rather than a broad prey spectrum found in nature. The work reported here seeks to fill these theoretical gaps by exploring the distinction between the ingestion kernel and the selection kernel. While the ingestion kernel describes which size classes can be potentially used by a consumer, the selection kernel depicts the actual size-dependent grazing on prey assemblages. Simple biomechanical laws show that the ingestion kernel takes a log-normal shape with a universal width (1/EMBED Equation.DSMT4 in log-diameter-space). Collected experimental data support the predicted constant value of the ingestible logarithmic size range across plankton taxa. The selection kernel resolves behavioral modifications during the capture process. In particular, the inverse of the variable kernel width, defines consumer selectivity as a quantitative behavioral trait. Small kernel width thus large selectivity values, represent an optimization by consumers towards high food availability. Optimality in selectivity is tested using observations on copepod grazing. Integral grazing rates that incorporate prey diversity and adaptive consumer selectivity are demonstrated to provide a sound mechanistic basis for size-based plankton models. %0 journal article %@ %A Khan, A., Lemmen, C. %D 2014 %J Arxiv.org, Physics, History and Philosophy of Physics %P 1303.1426 %T Bricks and urbanism in the Indus Valley rise and decline %U %X The Indus Civilization, often denoted by its major city Harappa, spanned almost two millennia from 3200 to 1300 BC. Its tradition reaches back to 7000 BC: a 5000 year long expansion of villages and towns, of trading activity, and of technological advancements culminates between 2600 and 1900 BC in the build-up of large cities, writing, and political authority; it emerges as one of the first great civilizations in history. During the ensuing 600 years, however, key technologies fall out of use, urban centers are depopulated, and people emigrate from former core settlement areas. Although many different hypotheses have been put forward to explain this deurbanization, a conclusive causal chain has not yet been established. We here combine literature estimates on brick typology, and on urban area for individual cities. In the context of the existing extensive data on Harappan artifact find sites and put in their chronological context, the combined narratives told by bricks, cities, and spatial extent can provide a new point of departure for discussing the possible reasons for the mysterious "decline". %0 journal article %@ 1616-7341 %A Pein, J.U., Stanev, E.V., Zhang, Y.J. %D 2014 %J Ocean Dynamics %N 12 %P 1719-1741 %R doi:10.1007/s10236-014-0772-z %T The tidal asymmetries and residual flows in Ems Estuary %U https://doi.org/10.1007/s10236-014-0772-z 12 %X A 3D unstructured-grid numerical model of the Ems Estuary is presented. The simulated hydrodynamics are compared against tidal gauge data and observations from research cruises. A comparison with an idealized test reveals the capability of the model to reproduce the secondary circulation patterns known from theoretical results. The simulations prove to be accurate and realistic, confirming and extending findings from earlier observations and modeling studies. The basic characteristics of dominant physical processes in the estuary such as tidal amplification, tidal damping, overtide generation, baroclinicity and internal mixing asymmetry are quantified. The model demonstrates an overall dominance of the flood currents in most of the studied area. However, the hypsometric control in the vicinity of Dollart Bay reverses this asymmetry, with the ebb currents stronger than the flood ones. Small-scale bathymetric characteristics and baroclinicity result in a very complex interplay between dominant physical mechanisms in different parts of the tidal channels and over the tidal flats. Residual flow reveals a clear overturning circulation in some parts of the estuary which is related to a mixing asymmetry between flood and ebb currents. We demonstrate that while areas close to the tidal river exhibit overall similarity with density controlled estuarine conditions, in large areas of the outer estuary barotropic forcing and complex bathymetry together with the density distribution affect substantially the horizontal circulation. %0 journal article %@ 0452-7739 %A Staneva, J., Behrens, A., Groll, N. %D 2014 %J Die Kueste %P 233-254 %T Recent Advances in Wave modeling for the North Sea and German Bight - Neueste Fortschritte in der Wellenmodellierung für die Nordsee und die Deutsche Bucht %U %X Modell haben zu einem großen Interesse geführt, die erzeugten Daten in industriellen Anwendungen zu nutzen. %0 journal article %@ 0452-7739 %A Weisse, R., Gaslikova, L., Geyer, B., Groll, N., Meyer, E. %D 2014 %J Die Kueste %P 5-18 %T CoastDat - Model Data for Science and Industry %U %X Validierungsergebnisse gegeben. Anschließend werden eine kurze Übersicht über derzeit existierende Anwendungen gegeben und die Zugangsmöglichkeiten zu den Daten beschrieben. %0 journal article %@ 0044-7447 %A Soomere, T., Doeoes, K., Lehmann, A., Meier, H.E.M., Murawski, J., Myrberg, K., Stanev, E. %D 2014 %J Ambio %N 1 %P 94-104 %R doi:10.1007/s13280-013-0486-3 %T The Potential of Current- and Wind-Driven Transport for Environmental Management of the Baltic Sea %U https://doi.org/10.1007/s13280-013-0486-3 1 %X The ever increasing impact of the marine industry and transport on vulnerable sea areas puts the marine environment under exceptional pressure and calls for inspired methods for mitigating the impact of the related risks. We describe a method for preventive reduction of remote environmental risks caused by the shipping and maritime industry that are transported by surface currents and wind impact to the coasts. This method is based on characterizing systematically the damaging potential of the offshore areas in terms of potential transport to vulnerable regions of an oil spill or other pollution that has occurred in a particular area. The resulting maps of probabilities of pollution to be transported to the nearshore and the time it takes for the pollution to reach the nearshore are used to design environmentally optimized fairways for the Gulf of Finland, Baltic Proper, and south-western Baltic Sea. %0 journal article %@ 0003-0007 %A Storch, H.v., Feser, F., Haeseler, S., Lefebvre, C., Stendel, M. %D 2014 %J Bulletin of the American Meteorological Society, Special Supplement "Explaining Extremes of 2013 from a Climate Perspective" %N 9 %P S 76-S 78 %R doi:10.1175/1520-0477-95.9.S1.1 %T A Violent Midlatitude Storm in Northern Germany and Denmark, 28 October 2013 %U https://doi.org/10.1175/1520-0477-95.9.S1.1 9 %X A strong storm on 28 October 2013 over northern Germany and southern Denmark fits a slight increase in storminess during recent decades. However, the increase constitutes part of multidecadal variability. %0 journal article %@ 0165-0009 %A Wetter, O., Pfister, C., Werner, J.P., Zorita, E., Wagner, S., Seneviratne, S.I., Herget, J., Gruenewald, U., Luterbacher, J., Alcoforado, M.-J., Barriendos, M., Bieber, U., Brazdil, R., Burmeister, K.-H., Camenisch, C., Contino, A., Dobrovolny, P., Glaser, R., Himmelsbach, I., Kiss, A., Kotyza, O., Labbe, T., Limanowka, D., Litzenburger, L., Nordl, Oe., Pribyl, K., Retsoe, D., Riemann, D., Rohr, C., Siegfried, W., Soederberg, J., Spring, J.-L. %D 2014 %J Climatic Change %N 3-4 %P 349-363 %R doi:10.1007/s10584-014-1184-2 %T The year-long unprecedented European heat and drought of 1540 – a worst case %U https://doi.org/10.1007/s10584-014-1184-2 3-4 %X The heat waves of 2003 in Western Europe and 2010 in Russia, commonly labelled as rare climatic anomalies outside of previous experience, are often taken as harbingers of more frequent extremes in the global warming-influenced future. However, a recent reconstruction of spring–summer temperatures for WE resulted in the likelihood of significantly higher temperatures in 1540. In order to check the plausibility of this result we investigated the severity of the 1540 drought by putting forward the argument of the known soil desiccation-temperature feedback. Based on more than 300 first-hand documentary weather report sources originating from an area of 2 to 3 million km2, we show that Europe was affected by an unprecedented 11-month-long Megadrought. The estimated number of precipitation days and precipitation amount for Central and Western Europe in 1540 is significantly lower than the 100-year minima of the instrumental measurement period for spring, summer and autumn. This result is supported by independent documentary evidence about extremely low river flows and Europe-wide wild-, forest- and settlement fires. We found that an event of this severity cannot be simulated by state-of-the-art climate models. %0 journal article %@ 0894-8755 %A Cavicchia, L., Storch, H.v., Gualdi, S. %D 2014 %J Journal of Climate %N 19 %P 7493-7501 %R doi:10.1175/JCLI-D-14-00339.1 %T Mediterranean Tropical-Like Cyclones in Present and Future Climate %U https://doi.org/10.1175/JCLI-D-14-00339.1 19 %X The Mediterranean has been identified as one of the most responsive regions to climate change. It has been conjectured that one of the effects of a warmer climate could be to make the Mediterranean Sea prone to the formation of hurricanes. Already in the present climate regime, however, a few of the numerous low pressure systems that form in the area develop a dynamical evolution similar to the one of tropical cyclones. Even if their spatial extent is generally smaller and the life cycle shorter compared to tropical cyclones, such storms produce severe damage on the highly populated coastal areas surrounding the Mediterranean Sea. This study, based on the analysis of individual realistically simulated storms in homogeneous long-term and high-resolution data from multiple climate change scenarios, shows that the projected effect of climate change on Mediterranean tropical-like cyclones is decreased frequency and a tendency toward a moderate increase of intensity. %0 journal article %@ 0165-0009 %A Wetter, O., Pfister, C., Werner, J.P., Zorita, E., Wagner, S., Seneviratne, S.I., Herget, J., Gruenewald, U., Luterbacher, J., Alcoforado, M.-J., Barriendos, M., Bieber, U., Brazdil, R., Burmeister, K.-H., Camenisch, C., Contino, A., Dobrovolny, P., Glaser, R., Himmelsbach, I., Kiss, A., Kotyza, O., Labbe, T., Limanowka, D., Litzenburger, L., Nordli, Oe., Pribyl, K., Retsoe, D., Riemann, D., Rohr, C., Siegfried, W., Soederberg, J., Spring, J.-L. %D 2014 %J Climatic Change %N 3-4 %P 365-367 %R doi:10.1007/s10584-014-1193-1 %T The year-long unprecedented European heat and drought of 1540 – a worst case %U https://doi.org/10.1007/s10584-014-1193-1 3-4 %X The heat waves of 2003 in Western Europe and 2010 in Russia, commonly labelled as rare climatic anomalies outside of previous experience, are often taken as harbingers of more frequent extremes in the global warming-influenced future. However, a recent reconstruction of spring–summer temperatures for WE resulted in the likelihood of significantly higher temperatures in 1540. In order to check the plausibility of this result we investigated the severity of the 1540 drought by putting forward the argument of the known soil desiccation-temperature feedback. Based on more than 300 first-hand documentary weather report sources originating from an area of 2 to 3 million km2, we show that Europe was affected by an unprecedented 11-month-long Megadrought. The estimated number of precipitation days and precipitation amount for Central and Western Europe in 1540 is significantly lower than the 100-year minima of the instrumental measurement period for spring, summer and autumn. This result is supported by independent documentary evidence about extremely low river flows and Europe-wide wild-, forest- and settlement fires. We found that an event of this severity cannot be simulated by state-of-the-art climate models. %0 journal article %@ 0964-5691 %A Busch, M., Kannen, A., Garthe, S., Jessopp, M. %D 2013 %J Ocean and Coastal Management %P 213-224 %R doi:10.1016/j.ocecoaman.2012.10.016 %T Consequences of a cumulative perspective on marine environmental impacts: offshore wind farming and seabirds at North Sea scale in context of the EU Marine Strategy Framework Directive %U https://doi.org/10.1016/j.ocecoaman.2012.10.016 %X Legal requirements in context of the EU Marine Strategy Framework Directive require increased trans-national cooperation on environmental effects induced by marine uses to achieve Good Environmental Status by 2020. Interactions between offshore wind farms and seabirds represent a valuable example of how a changed spatial perspective might influence the assessment of environmental impacts. This paper addresses the potential consequences of offshore wind farm development at the North Sea scale on selected seabird species with high relevance in context of national approval procedures. It provides a new methodology to estimate the cumulative habitat loss due to ongoing and planned offshore wind farm construction activities within the North Sea’s exclusive economic zones of Germany, the Netherlands, Belgium and the United Kingdom. In addition to providing information on the seasonal distribution of important species and initial estimates of potential seabird habitat exclusion due to offshore wind farming, this study highlights the need for increased trans-national cooperation among riparian states and harmonization of conservation approaches to successfully implement the Marine Strategy Framework Directive. %0 journal article %@ 0964-5691 %A Mayer, I., Zhou, Q., Lo, J., Abspoel, L., Keijser, X., Olsen, E., Nixon, E., Kannen, A. %D 2013 %J Ocean and Coastal Management %P 7-26 %R doi:10.1016/j.ocecoaman.2013.04.006 %T Integrated, ecosystem-based Marine Spatial Planning: Design and results of a game-based, quasi-experiment %U https://doi.org/10.1016/j.ocecoaman.2013.04.006 %X The authors analyse the complexity of Marine Spatial Planning (MSP) and explore the role that simulation gaming (SG) could play in addressing it. They present the set-up of and insights from a game-based, quasi-experimental study and policy intervention involving MSP. The simulation game MSP Challenge 2011 was played in Lisbon on 3 November 2011 by 68 international MSP professionals – mainly scientists, policy advisers and marine spatial planners – from 16 countries. Data on MSP in the various countries, as well as on the effectiveness of the policy intervention, were collected using pre-game, in-game and post-game questionnaires, combined with the analysis of MSP processes and outcomes in a digital map tool and observations. The analysis shows that MSP lends itself to comparative assessment in real and simulated environments. Observed variety and changes in the game-based intervention provide evidence that the participants engaged in experimentation with different strategies, policy change and policy-oriented learning. The game-based intervention proved an effective and promising method for national/international experimentation and exchange among professional MSP planners. %0 journal article %@ 0094-8276 %A Gomez-Navarro, J.J., Zorita, E. %D 2013 %J Geophysical Research Letters %N 12 %P 3232-3236 %R doi:10.1002/grl.50628 %T Atmospheric annular modes in simulations over the past millennium: No long-term response to external forcing %U https://doi.org/10.1002/grl.50628 12 %X This study analyzes whether the imprint of external forcings can be detected in the long-term evolution of the main atmospheric circulation patterns in climate simulations over the last millennium. The external forcing is not found to significantly add variability in any frequency band compared to control simulations where the external drivers are kept constant. Additionally, a method designed to detect a common signal in the time evolution of these circulation patterns among all simulations is proposed, and employed to demonstrate that the null hypothesis of an evolution dominated by internal variability cannot be rejected regardless of the time smoothing applied to the series. Given that the fingerprint of external forcings on atmospheric circulation has been successfully detected in simulations of the 20th century climate and in future climate change projections, we argue that either the effect of past natural forcing is too small, state-of-the-art climate models underestimate their climate sensitivity, or the anthropogenic forcing qualitatively differs from the natural forcing in its effect on main circulation patterns. %0 journal article %@ 1994-0416 %A Klehmet, K., Geyer, B., Rockel, B. %D 2013 %J The Cryosphere %N 4 %P 1017-1034 %R doi:10.5194/tc-7-1017-2013 %T A regional climate model hindcast for Siberia: Analysis of snow water equivalent %U https://doi.org/10.5194/tc-7-1017-2013 4 %X This study analyzes the added value of a regional climate model hindcast with respect to snow water equivalent (SWE) for Siberia when compared to SWE estimates from forcing NCEP-R. In addition, we examine the discrepancies of simulated SWE to several recent reanalysis products (NCEP-R2 NCEP-CFSR, ERA-Interim). We apply the regional climate model COSMO-CLM (CCLM) to a 50 km grid spacing using NCEP-R1 as driving force to obtain a 63 yr (1948 to 2010) gridded dataset of historical SWE. Simulated regional climate data is necessary because of the absence of station data in that region. To perform large-scale assessments we use the satellite-derived daily SWE product of ESA DUE GlobSnow from 1987 to 2010. Russian station SWE data is used for cross-checking the findings. In January (mid-winter), the SWE hindcast is in good agreement with GlobSnow, whereas it overestimates SWE during the melting season. CCLM shows a clear added value in providing realistic SWE information compared to the driving reanalysis. The temporal consistency of CCLM is higher than that presented by ERA-Interim and NCEP-R2. %0 journal article %@ 1752-0894 %A Ahmed, M., Anchukaitis, K.J., Asrat, A., Borgaonkar, H.P., Braida, M., Buckley, B.M., Buentgen, U., Chase, B.M., Christie, D.A., Cook, E.R., Curran, M.A.J., Diaz, H.F., Esper, J., Fan, Z.-X., Gaire, N.P., Ge, Q., Gergis, J., Gonzalez-Rouco, J.F., Goosse, H., Grab, S.W., Graham, N., Graham, R., Grosjean, M., Hanhijaervi, S.T., Kaufman, D.S., Kiefer, T., Kimura, K., Korhola, A.A., Krusic, P.J., Lara, A., Lezine, A.-M., Ljungqvist, F.C., Lorrey, A.M., Luterbacher, J., Masson-Delmotte, V., McCarroll, D., McConnell, J.R., McKay, N.P., Morales, M.S., Moy, A.D., Mulvaney, R. %A Mundo, I.A., Nakatsuka, T., Nash,D.J., Neukom, R., Nicholson, S.E., Oerter, H., Palmer, J.G., Phipps, S.J., Prieto, M.R., Rivera, A., Sano, M., Severi, M., Shanahan, T.M., Shao, X., Shi, F., Sigl, M., Smerdon, J.E., Solomina, O.N., Steig, E.J., Stenni, B., Thamban, M., Trouet, V., Turney, C.S.M., Umer, M., Ommen, T. van, Verschuren, D., Viau, A.E., Villalba, R., Vinther, B.M., Gunten, L.v., Wagner, S., Wahl, E.R., Wanner, H., Werner, J.P., White, J.W.C., Yasue, K., Zorita, E. %D 2013 %J Nature Geoscience %N 5 %P 339-346 %R doi:10.1038/NGEO1797 %T Continental-scale temperature variability during the past two millennia %U https://doi.org/10.1038/NGEO1797 5 %X Past global climate changes had strong regional expression. To elucidate their spatio-temporal pattern, we reconstructed past temperatures for seven continental-scale regions during the past one to two millennia. The most coherent feature in nearly all of the regional temperature reconstructions is a long-term cooling trend, which ended late in the nineteenth century. At multi-decadal to centennial scales, temperature variability shows distinctly different regional patterns, with more similarity within each hemisphere than between them. There were no globally synchronous multi-decadal warm or cold intervals that define a worldwide Medieval Warm Period or Little Ice Age, but all reconstructions show generally cold conditions between ad 1580 and 1880, punctuated in some regions by warm decades during the eighteenth century. The transition to these colder conditions occurred earlier in the Arctic, Europe and Asia than in North America or the Southern Hemisphere regions. Recent warming reversed the long-term cooling; during the period ad 1971–2000, the area-weighted average reconstructed temperature was higher than any other time in nearly 1,400 years. %0 journal article %@ 0899-8418 %A Springer, C., Matulla, C., Schoener, W., Steinacker, R., Wagner, S. %D 2013 %J International Journal of Climatology %N 5 %P 1270-1279 %R doi:10.1002/joc.3511 %T Downscaled GCM projections of winter and summer mass balance for Central European glaciers (2000–2100) from ensemble simulations with ECHAM5-MPIOM %U https://doi.org/10.1002/joc.3511 5 %X This study is based on the study from Matulla et al. (2009) where the glacier under estimation has been Peyto Glacier in Canada. The same methods have been used for five Austrian glaciers; projections of glacier mass balance are generated from ensembles of general circulation model (GCM) simulations by the use of direct statistical downscaling. Thereby, the general features of the atmospheric circulation over an expanded geographical region covering the European Alps are linked empirically to winter and summer mass balance records measured at five glaciers in Austria. The projections are taken from an ensemble of ECHAM5-MPIOM simulations forced with the IPCC-SRES scenarios A1B and B1. Results based on the statistical downscaling indicate decreasing balances for both winter and summer. These results suggest continued frontal recession and downwasting of the alpine glaciers in this region until 2100. For Jamtalferner, these suggestions reach reductions of about 1000 mm water equivalent in summer. %0 journal article %@ 0930-7575 %A Barkhordarian, A., Storch, H.v., Bhend, J. %D 2013 %J Climate Dynamics %N 1-2 %P 225-244 %R doi:10.1007/s00382-012-1497-7 %T The expectation of future precipitation change over the Mediterranean region is different from what we observe %U https://doi.org/10.1007/s00382-012-1497-7 1-2 %X In this study we assess the role of anthropogenic forcing (greenhouse gases and sulphate aerosols, GS) in recently observed precipitation trends over the Mediterranean region. We investigate whether the observed precipitation trends (1966–2005 and 1979–2008) are consistent with what 22 models project as response of precipitation to GS forcing. Significance is estimated using 9,000-year control runs derived from the CMIP3 archive. The results indicate that externally forced changes are detectable in observed precipitation trends in winter, late summer and in autumn. Natural internal climate variability cannot explain these changes. However, the observed trends (derived from 3 sources) are markedly inconsistent with expected changes due to GS forcing. While the influence of GS signal is detectable in winter and early spring, observed changes are several times larger than the projected response to GS forcing. The most striking inconsistency, however, is the contradiction between projected drying and the observed increase in precipitation in late summer and autumn, irrespective of the data set used. Natural (internal) variability as estimated from the models cannot account for these inconsistencies, which are already present in the large scale circulation patterns (Geopotential height at 500 hPa). The obtained results are robust to the removal of the fingerprint of the North Atlantic Oscillation. The detection of an outright sign mismatch of observed and projected trends in autumn and late summer, leads us to conclude that the recently observed trends can not be used as an illustration of plausible future expected change in the Mediterranean region. These significant shortcomings in our understanding of recent observed changes complicate communication of future expected changes in Mediterranean precipitation. %0 journal article %@ 0091-7613 %A Mayr, C., Luecke, A., Wagner, S., Wissel, H., Ohlendorf, C., Haberzettl, T., Oehlrich, M., Schaebitz, F., Wille, M., Zhu, J., Zolitschka, B. %D 2013 %J Geology %N 8 %P 831-834 %R doi:10.1130/G34335.1 %T Intensified Southern Hemisphere Westerlies regulated atmospheric CO2 during the last deglaciation %U https://doi.org/10.1130/G34335.1 8 %X The causes for the rise of atmospheric CO2 during the last deglaciation are complex and remain a matter of controversial scientific discussion. One hypothesis explains this phenomenon with CO2 release from the deep ocean. A change in atmosphere-ocean interaction induced by a shift or intensification of Southern Hemisphere Westerlies (SHW) could have stimulated this process. Here this hypothesis is tested using oxygen isotope ratios of aquatic cellulose from Patagonian lacustrine sediments as west-wind proxy. Our record indicates maximum SHW strength at 52°S between 13.4 and 11.3 calibrated kyr B.P. This is in agreement with an increase in zonal wind strength extending to the southern mid-latitudes during the Younger Dryas chronozone triggering the final CO2 increase. Comparison with other Southern Hemisphere records implies southward migration of strengthened SHW at that time, leading to interglacial CO2 levels and hence terminating the Last Glacial. %0 journal article %@ 0959-6836 %A Ackerley, D., Lorrey, A., Renwick, J., Phipps, S.J., Wagner, S., Fowler, A. %D 2013 %J The Holocene %N 9 %P 1272-1285 %R doi:10.1177/0959683613484612 %T High-resolution modelling of mid-Holocene New Zealand climate at 6000 yr BP %U https://doi.org/10.1177/0959683613484612 9 %X Palaeoclimate-proxy data provide an invaluable source of evidence for past climatic conditions, which can be compared with data from climate model simulations. This study illustrates how high-resolution regional climate model simulations can be used to estimate the difference in the climate of New Zealand between 6000 years before present (yr BP) and the pre-industrial era (c. ad 1750). Four pairs (pre-industrial and 6000 yr BP) of atmosphere-only global and regional climate model simulations were run with prescribed sea surface temperatures (SST). The SSTs are derived from four different fully coupled ocean–atmosphere general circulation model simulations, resulting in a different lower-boundary forcing in each of the atmosphere-only simulations. We find evidence for generally cooler conditions and for wetter (drier) conditions over eastern (western) New Zealand 6000 yr BP. The work compares well with model and proxy estimates of temperature and precipitation in the New Zealand region between 7000 and 6000 yr BP. The results also highlight the added value of regional model studies in regions with such complex terrain as New Zealand. This study also shows the limitations of applying uniformitarian principles when downscaling global model fields (and ‘up-scaling’ palaeo-proxy data) to infer past climatic conditions. %0 journal article %@ 0142-7873 %A Wirtz, K.W. %D 2013 %J Journal of Plankton Research %N 1 %P 33-48 %R doi:10.1093/plankt/fbs075 %T How fast can plankton feed? Maximum ingestion rate scales with digestive surface area %U https://doi.org/10.1093/plankt/fbs075 1 %X Allometric scaling rules have been classically used in plankton ecology to describe how the maximum ingestion rate (Imax) under steady-state conditions changes with the body size of the consumer. Empirical and theoretical concerns, however, motivate a more accurate and mechanistic description of size–ingestion relations. Here, I propose to relate Imax to the digestive surface area, which expresses the capacity in preprocessing and digesting food items. This surface area depends on both the body size and the optimal prey size of the consumer. The allometry in Imax, hence, includes a second major variable which describes different feeding modes within a consumer size class. Species with a small optimal-prey-to-predator-size ratio and, thus, a small “internal” surface-to-volume ratio, as is typical for filter feeders, have large intra-body transport lengths and lower Imax than raptorial-feeding species of the same body size. Digestive surface scaling tries to mechanistically accommodate feeding ecology, physiology and geometry. It does not explicitly resolve further possible factors affecting maximal ingestion such as nutritional quality. Still, digestive surface scaling explains the variability in published data compilations better than classical approaches when applied to the entire plankton size range. This is corroborated in further applications where the theory precisely fits anomalously steep scaling relations reported for heterotrophic nanoflagellates, ctenophores and a scyphomedusa. By introducing feeding mode and related morphological diversity into the size-dependency in ingestion rates, digestive surface scaling can be expected to improve the accuracy of size-based plankton models. %0 journal article %@ 1862-4065 %A Holdschlag, A., Ratter, B.M.W. %D 2013 %J Sustainability Science %N 3 %P 407-421 %R doi:10.1007/s11625-013-0216-6 %T Multiscale system dynamics of humans and nature in The Bahamas: perturbation, knowledge, panarchy and resilience %U https://doi.org/10.1007/s11625-013-0216-6 3 %X The analysis of the dynamic interactions between social systems, integrated by governance and communication, and biophysical systems, connected by material and energy flows, remains a challenge. In this paper, we draw on the heuristic models of the “adaptive renewal cycle” and “panarchy” [Gunderson and Holling (eds) Panarchy: understanding transformations in human and natural systems. Island Press, Washington, 2002], which are embedded in the theory of complex adaptive systems. Taking island development research in The Bahamas as a case study, we investigate environmental stressors, knowledge and social response in the context of three distinct social–ecological subsystems: (1) the interaction between tropical storms/hurricanes and the social system of disaster preparedness/management; (2) coastal ecosystem degradation coupled with land development; and (3) the fishery, in which we also consider the impact of a recent biological invasion, the Indo-Pacific red lionfish. The findings demonstrate the complexity of panarchical relations and the crucial role of diverse and uncertain knowledge systems and underlying mental models of risk and environment for resilience and sustainability. These are acquired at different scales and form key variables of change. This also applies to processes of communication. Bringing together the various constantly evolving multi-level knowledge systems for effective communication and decision-making remains a major challenge. %0 journal article %@ 0921-030X %A Gaslikova, L., Grabemann, I., Groll, N. %D 2013 %J Natural Hazards %N 3 %P 1501-1518 %R doi:10.1007/s11069-012-0279-1 %T Changes in North Sea storm surge conditions for four transient future climate realizations %U https://doi.org/10.1007/s11069-012-0279-1 3 %X Storm surges in the North Sea are one of the threats for coastal infrastructure and human safety. Under an anthropogenic climate change, the threat of extreme storm surges may be enlarged due to changes in the wind climate. Possible future storm surge climates based on transient simulations (1961–2100) are investigated with a hydrodynamical model for the North Sea. The climate change scenarios are based on regionalized meteorological conditions with the regional climate model CCLM which is forced by AR4 climate simulations with the general circulation model ECHAM5/MPIOM under two IPCC emission scenarios (SRES A1B and B1) and two initial conditions. Possible sea level rise in the North Sea is not taken into account. The analysis of future wind-induced changes of the water levels is focused on extreme values. Special emphasis is given to the southeastern North Sea (German Bight). Comparing the 30-year averages of the annual 99 percentiles of the wind-induced water levels between the four climate realizations and the respective control climates, a small tendency toward an increase is inferred for all climate change realizations toward the end of the twenty-first century. Concerning the German Bight, the climate change signals are higher for the North Frisian coastal areas than for the East Frisian ones. This is consistent with an increase in frequency of strong westerly winds. Considering the whole time series (1961–2100) for selected areas, this tendency is superimposed with strong decadal fluctuations. It is found that uncertainties are related not only to the used models and emission scenarios but also to the initial conditions pointing to the internal natural variability. %0 journal article %@ 0894-8755 %A Krueger, O., Schenk, F., Feser, F., Weisse, R. %D 2013 %J Journal of Climate %N 3 %P 868-874 %R doi:10.1175/JCLI-D-12-00309.1 %T Inconsistencies between long-term trends in storminess derived from the 20CR reanalysis and observations %U https://doi.org/10.1175/JCLI-D-12-00309.1 3 %X Global atmospheric reanalyses have become a common tool for both the validation of climate models and diagnostic studies, such as assessing climate variability and long-term trends. Presently, the 20th Century Reanalysis (20CR), which assimilates only surface pressure reports, sea-ice, and sea surface temperature distributions, represents the longest global reanalysis dataset available covering the period from 1871 to the present. Currently, the 20CR dataset is extensively used for the assessment of climate variability and trends. Here, we compare the variability and long-term trends in Northeast Atlantic storminess derived from 20CR and from observations. A well established storm index derived from pressure observations over a relatively densely monitored marine area is used. It is found that both, variability and long-term trends derived from 20CR and from observations, are inconsistent. In particular, both time series show opposing trends during the first half of the 20th century. Only for the more recent periods both storm indices share a similar behavior. While the variability and long-term trend derived from the observations are supported by a number of independent data and analyses, the behavior shown by 20CR is quite different, indicating substantial inhomogeneities in the reanalysis most likely caused by the increasing number of observations assimilated into 20CR over time. The latter makes 20CR likely unsuitable for the identification of trends in storminess in the earlier part of the record at least over the Northeast Atlantic. Our results imply and reconfirm previous findings that care is needed in general, when global reanalyses are used to assess long-term changes. %0 journal article %@ 0148-0227 %A Mueller, S., Stanev, E.V., Schulz.Stellenfleth, J., Staneva, J., Koch, W. %D 2013 %J Journal of Geophysical Research : Oceans %N 10 %P 5036-5053 %R doi:10.1002/jgrc.20388 %T Atmospheric boundary layer rolls: Quantification of their effect on the hydrodynamics in the German Bight %U https://doi.org/10.1002/jgrc.20388 10 %X Atmospheric boundary layer rolls and their impact on upper ocean circulation were investigated using a combination of two high-resolution data sources: (1) data from the Advanced Synthetic Aperture Radar (ASAR) onboard ENVISAT with a spatial sampling of approximately 500 m × 500 m and (2) continuous observations taken at the research platform FINO 1 with 2 min temporal sampling at eight heights between 33 and 100 m. The parallel analysis of instantaneous image data in combination with the FINO 1 time series enabled us to quantify both the spatial and temporal dynamics of mesoscale and submesoscale wind variations. The influence of these variations with different temporal and spatial scales on the hydrodynamics of the German Bight was addressed using outputs from a three-dimensional circulation model. It was demonstrated that while the coupling between wind and tidal forcing triggered substantial responses at mesoscales, the response of surface currents and sea surface temperature to the atmospheric boundary layer rolls appeared relatively weak. However, these ocean surface responses closely follow the surface footprint of the atmospheric boundary layer rolls, the signatures of which become more pronounced in the absence of strong tidal flows. %0 journal article %@ 0930-7575 %A Xia, L., Storch, H.v., Feser, F. %D 2013 %J Climate Dynamics %N 3-4 %P 901-916 %R doi:10.1007/s00382-012-1543-5 %T Quasi-stationarity of centennial Northern Hemisphere midlatitude winter storm tracks %U https://doi.org/10.1007/s00382-012-1543-5 3-4 %X The winter storm activity on the Northern Hemisphere during the last one thousand years in a global climate simulation was analyzed by determining all midlatitude storms and their tracks, then consecutively clustering them for hundred years’ segments. Storm track clusters with longest lifetime and largest deepening rates are found over the oceans. The numbers of extratropical winter storms exhibit notable yearly variability but hardly any variability on centennial time scales. The clusters of these storm tracks also show only small differences between the centuries. The numbers of members in neighboring oceanic clusters are negatively correlated. A linear relationship was found between the numbers of members per storm track clusters over the Pacific or Atlantic Ocean and seasonal mean atmospheric circulation patterns by a canonical correlation analysis. %0 journal article %@ 1563-0102 %A Lemmen, C. %D 2013 %J Archeologija, Etnografija i Antropologija Evrazii %N 3 %P 48-58 %T Different mechanisms shaped the transition to farming in Europe and the North American Woodland - %U 3 %X Absract in russisch %0 journal article %@ 1814-9324 %A Gomez-Navarro, J.J., Montavez, J.P., Wagner, S., Zorita, E. %D 2013 %J Climate of the Past %N 4 %P 1667-1682 %R doi:10.5194/cp-9-1667-2013 %T A regional climate palaeosimulation for Europe in the period 1500–1990 – Part 1: Model validation %U https://doi.org/10.5194/cp-9-1667-2013 4 %X We present and analyse a high-resolution regional climate palaeosimulation encompassing the European region for the period 1500–1990. We use the regional model MM5 driven at the boundaries by the global model ECHO-G. Both models are forced by reconstructions of three external factors: greenhouse gas concentrations, total solar irradiance and volcanic activity. The simulation skill is assessed in a recent period by comparing the model results with the Climate Research Unit (CRU) database. The results show that although the regional model is tightly driven by the boundary conditions, it is able to improve the reliability of the simulations, narrowing the differences to the observations, especially in areas of complex topography. Additionally, the evolution of the spatial distributions of temperature and precipitation through the last five centuries is analysed, showing that the mean values of temperature reflects the influence of the external forcings. However, contrary to the results obtained under climate change scenario conditions, higher-order momenta of seasonal temperature and precipitation are hardly affected by changes in the external forcings. %0 journal article %@ 0921-030X %A Kremer, H., Nicholls, R., Ratter, B.M.W., Weisse, R. %D 2013 %J Natural Hazards %P 1293-1294 %R doi:10.1007/s11069-013-0613-2 %T Interdisciplinary Research and Perspectives on Current and Future Storm Surges %U https://doi.org/10.1007/s11069-013-0613-2 %X sound interdisciplinary approaches. %0 journal article %@ 0012-8252 %A Wahl, T., Haigh, I.D., Woodworth, P.L., Albrecht, F., Dillingh, D., Jensen, J., Nicholls, R.J., Weisse, R., Woeppelmann, G. %D 2013 %J Earth-Science Reviews %P 51-67 %R doi:10.1016/j.earscirev.2013.05.003 %T Observed mean sea level changes around the North Sea coastline from 1800 to present %U https://doi.org/10.1016/j.earscirev.2013.05.003 %X This paper assesses historic changes in mean sea level around the coastline of the North Sea, one of the most densely populated coasts in the world. Typically, such analyses have been conducted at a national level, and detailed geographically wider analyses have not been undertaken for about 20 years. We analyse long records (up to 200 years) from 30 tide gauge sites, which are reasonably uniformly distributed along the coastline, and: (1) calculate relative sea level trends; (2) examine the inter-annual and decadal variations; (3) estimate regional geocentric (sometimes also referred to as ‘absolute’) sea level rise throughout the 20th century; and (4) assess the evidence for regional acceleration of sea-level rise. Relative sea level changes are broadly consistent with known vertical land movement patterns. The inter-annual and decadal variability is partly coherent across the region, but with some differences between the Inner North Sea and the English Channel. Data sets from various sources are used to provide estimates of the geocentric sea level changes. The long-term geocentric mean sea level trend for the 1900 to 2011 period is estimated to be 1.5 ± 0.1 mm/yr for the entire North Sea region. The trend is slightly higher for the Inner North Sea (i.e. 1.6 ± 0.1 mm/yr), and smaller but not significantly different on the 95% confidence level for the English Channel (i.e. 1.2 ± 0.1 mm/yr). The uncertainties in the estimates of vertical land movement rates are still large, and the results from a broad range of approaches for determining these rates are not consistent. Periods of sea level rise acceleration are detected at different times throughout the last 200 years and are to some extent related to air pressure variations. The recent rates of sea level rise (i.e. over the last two to three decades) are high compared to the long-term average, but are comparable to those which have been observed at other times in the late 19th and 20th century. %0 journal article %@ 0894-8755 %A Semedo, A., Weisse, R., Behrens, A., Sterl, A., Bengtsson, L., Guenther, H. %D 2013 %J Journal of Climate %N 21 %P 8269-8288 %R doi:10.1175/JCLI-D-12-00658.1 %T Projection of Global Wave Climate Change toward the End of the Twenty-First Century %U https://doi.org/10.1175/JCLI-D-12-00658.1 21 %X Wind-generated waves at the sea surface are of outstanding importance for both their practical relevance in many aspects, such as coastal erosion, protection, or safety of navigation, and for their scientific relevance in modifying fluxes at the air–sea interface. So far, long-term changes in ocean wave climate have been studied mostly from a regional perspective with global dynamical studies emerging only recently. Here a global wave climate study is presented, in which a global wave model [Wave Ocean Model (WAM)] is driven by atmospheric forcing from a global climate model (ECHAM5) for present-day and potential future climate conditions represented by the Intergovernmental Panel for Climate Change (IPCC) A1B emission scenario. It is found that changes in mean and extreme wave climate toward the end of the twenty-first century are small to moderate, with the largest signals being a poleward shift in the annual mean and extreme significant wave heights in the midlatitudes of both hemispheres, more pronounced in the Southern Hemisphere and most likely associated with a corresponding shift in midlatitude storm tracks. These changes are broadly consistent with results from the few studies available so far. The projected changes in the mean wave periods, associated with the changes in the wave climate in the middle to high latitudes, are also shown, revealing a moderate increase in the equatorial eastern side of the ocean basins. This study presents a step forward toward a larger ensemble of global wave climate projections required to better assess robustness and uncertainty of potential future wave climate change. %0 journal article %@ %A Lemmen, C., Hofmeister, R., Wirtz, K. %D 2013 %J KFKI aktuell : Mitteilungen des Kuratoriums fuer Forschung im Kuesteningenieurwesen %N 2 %P 8-10 %T Das Modulare System fuer Schelfmeere und Kuesten (MOSSCO) - Konzepte und Infrastruktur zum Zusammenwirken verschiedener Modelle fuer die Kuestenforschung %U 2 %X No abstract %0 journal article %@ 0278-4343 %A Hofmeister, R., Bolding, K., Hetland, R,D., Schernewski, G., Siegel, H., Burchard, H. %D 2013 %J Continental Shelf Research %P 68-77 %R doi:10.1016/j.csr.2013.10.006 %T The dynamics of cooling water discharge in a shallow, non-tidal embayment %U https://doi.org/10.1016/j.csr.2013.10.006 %X The dynamics of cooling water spreading in a non-tidal embayment is subject of a modelling-based study of Greifswald Bay, a shallow embayment at the south-western coast of the Baltic Sea. Potential cooling water spreading due to a possible power plant at Greifswald Bay is evaluated as differences between a realistic hind-cast simulation and a similar simulation but including the cooling water pumping. The model results are confirmed with satellite imagery of the embayment during operation of a nuclear power plant in the 1980s. The effect of cooling water pumping on the residual circulation, additional stratification and the heating of near-bed waters in the herring spawning areas is evaluated from the simulation. The model results for an idealised embayment and the realistic scenario, as well as the satellite images, show a clear dependence of the plume spreading on the wind direction. Although the surface plume affects a large area of the embayment, the results show a localised impact on residual circulation, bulk stratification and heating of the waterbody. %0 journal article %@ 0094-8276 %A Stanev, E.V., He, Y., Grayek, S., Boetius, A. %D 2013 %J Geophysical Research Letters %N 12 %P 3085-3090 %R doi:10.1002/grl.50606 %T Oxygen dynamics in the Black Sea as seen by Argo profiling floats %U https://doi.org/10.1002/grl.50606 12 %X Observations collected in the Black Sea from May 2010 until December 2011 from two Argo floats with oxygen sensors demonstrated the potential of the applied technique to deliver high-quality oxygen data in this oxic/anoxic environment where the oxygen concentration varies from the level of saturation to zero. It was demonstrated that the dynamics of the oxic-anoxic interface was dominated by vigorous mesoscale processes displacing locally anoxic waters up to about 70 m below the sea surface. Alternatively, oxygenation (ventilation) in the coastal zone penetrated down to about 150–200 m. The range of mesoscale variability, which appeared to reach half of the range of climatic trend during the last 50 years, helped to objectively assess the validity of interpretation of historical data. It was proved that the shift of the suboxic zone from isopycnal depth σt = 16.5 to σt = 15.5 during 1960–2010, interrupted by its deepening between 1990 and 2000, was greater than the possible error limit caused by insufficient sampling of mesoscale variability. Furthermore, profiling floats shed a new light into the seasonal variability of the subsurface oxygen maximum. It was also demonstrated that the assumption of isopycnal alignment of oxygen was coarsely applicable to the suboxic layer in both the coastal and interior part of the Black Sea where the isopycnal mixing revealed large temporal and spatial variability. Therefore, deeper understanding of the dynamics of suboxic zone necessitated continuous basin-wide sampling. %0 journal article %@ 1753-318X %A Ge, J., Much, D., Kappenberg, J., Nino, O., Ding, P., Chen, Z. %D 2013 %J Journal of Flood Risk Management %N 4 %P 319-331 %R doi:10.1111/jfr3.12054 %T Simulating storm flooding maps over HafenCity under present and sea level rise scenarios %U https://doi.org/10.1111/jfr3.12054 4 %X In the long-term scenario (2085), flooding near the Magdeburger Hafen and Norderelbe will also increase. Coastal defence measures should be taken to ensure flood protection around HafenCity. %0 journal article %@ 0280-6495 %A Xia, L., Zahn, M., Hodges, K.I., Feser, F. %D 2012 %J Tellus A %P 17196 %R doi:10.3402/tellusa.v64i0.17196 %T A comparison of two identification and tracking methods for polar lows %U https://doi.org/10.3402/tellusa.v64i0.17196 %X In this study, we compare two different cyclone-tracking algorithms to detect North Atlantic polar lows, which are very intense mesoscale cyclones. Both approaches include spatial filtering, detection, tracking and constraints specific to polar lows. The first method uses digital bandpass-filtered mean sea level pressure (MSLP) fieldsin the spatial range of 200-600 km and is especially designed for polar lows. The second method also uses a bandpass filter but is based on the discrete cosine transforms (DCT) and can be applied to MSLP and vorticity fields. The latter was originally designed for cyclones in general and has been adapted to polar lows for this study. Both algorithms are applied to the same regional climate model output fields from October 1993 to September 1995 produced from dynamical downscaling of the NCEP/NCAR reanalysis data. Comparisons between these two methods show that different filters lead to different numbers and locations of tracks. The DCT is more precise in scale separation than the digital filter and the results of this study suggest that it is more suited for the bandpass filtering of MSLP fields. The detection and tracking parts also influence the numbers of tracks although less critically. After a selection process that applies criteria to identify tracks of potential polar lows, differences between both methods are still visible though the major systems are identified in both. %0 journal article %@ 1462-9011 %A Ratter, B.M.W., Philipp, K.H.I., Storch, H.v. %D 2012 %J Environmental Science & Policy %P 3-8 %R doi:10.1016/j.envsci.2011.12.007 %T Between hype and decline: recent trends in public perception of climate change %U https://doi.org/10.1016/j.envsci.2011.12.007 %X Several surveys around the world claim that the issue of climate change is of declining interest among the population. Hamburg, regularly experiencing storm surges and suffered a major flood in 1962, shows evidence of this tendency in yearly surveys undertaken from 2008 to 2011. Comparing detected trends in public awareness of climate change around the western world, this paper concludes that there is a decline in public concern about climate change in the last few years. A few surveys in the US reaching back to the 1990s indicate that this decline may be intermittent; data suggest that the long-term increase in scientific confidence and in media coverage is not transferred in a parallel long-term increase in public concern about climate change. %0 journal article %@ 0096-3941 %A Krauss, W., Storch, H.v. %D 2012 %J Eos - Transactions %N 10 %P 110 %R doi:10.1029/2012EO100007 %T Climate Science in a Postnormal Context %U https://doi.org/10.1029/2012EO100007 10 %X Climate research has left the narrow confines of pure science and has entered the public arena. At a workshop organized by Helmholtz Research Centre Geesthacht and the KlimaCampus, University of Hamburg, experts from the cultural, social, and natural sciences discussed the current state of climate science through the lens of “postnormal science” (see, e.g., S. O. Funtowicz and J. R. Ravetz, “Science for the postnormal age,” Futures, 25, 739–755, 1993). Science turns postnormal when facts are uncertain, stakes are high, values are disputed, and decisions are urgent. During the workshop, situations and practices in climate research were identified and discussed to provide a solid empirical basis for a more realistic definition of climate science. %0 journal article %@ 1600-0706 %A Malzahn, A.M., Boersma, M. %D 2012 %J Oikos : A Journal of Ecology %N 9 %P 1408-1416 %R doi:10.1111/j.1600-0706.2011.20186.x %T Effects of poor food quality on copepod growth are dose dependent and non-reversible %U https://doi.org/10.1111/j.1600-0706.2011.20186.x 9 %X Herbivores regularly face imbalanced diets on a variety of timescales. They respond to such diets with reductions in growth and reproduction. The effect of exposure time to poor quality diets and recovery potential in herbivores has yet not been intensively studied. In order to investigate the response of herbivores growth and nutritional condition to phosphorus limited algal food, we fed the copepod Acartia tonsa with the autotrophic flagellate Rhodomonas salina, which was cultured towards high and low phosphorus content. To test the effect of the duration of the exposure to low and high P food on copepod growth, we also switched a subset of the copepods from high P to low P food for two to 12 days before putting them back on their original diet. Phosphorus limited prey clearly reduced copepod nutritional condition, expressed as their RNA:DNA ratio and consequently their growth rates. Several days after re-feeding on high P algae, the copepods were able to reach growth rates comparable to the control groups, but they were in no case able to over shoot the growth rates of the control groups. A dose of two days feeding on low P algae resulted in slightly less than one stage growth reduction compared to copepods exclusively reared on high P algae. Our results show that phosphorus limited food drastically reduces secondary production, and no compensatory growth occurs in the investigated copepod species. Hence, even short term exposure of herbivores to poor food has a lasting effect on secondary production. %0 journal article %@ 1812-0784 %A Soomere, T., Weisse, R., Behrens, A. %D 2012 %J Ocean Science %N 2 %P 287-300 %R doi:10.5194/os-8-287-2012 %T Wave climate in the Arkona Basin, the Baltic Sea %U https://doi.org/10.5194/os-8-287-2012 2 %X The basic features of the wave climate in the Southwestern Baltic Sea (such as the average and typical wave conditions, frequency of occurrence of different wave parameters, variations in wave heights from weekly to decadal scales) are established based on waverider measurements at the Darss Sill in 1991–2010. The measured climate is compared with two numerical simulations with the WAM wave model driven by downscaled reanalysis of wind fields for 1958–2002 and by adjusted geostrophic winds for 1970–2007. The wave climate in this region is typical for semi-enclosed basins of the Baltic Sea. The maximum wave heights are about half of those in the Baltic Proper. The maximum recorded significant wave height HS =4.46 m occurred on 3 November 1995. The wave height exhibits no long-term trend but reveals modest interannual (about 12 % of the long-term mean of 0.76 m) and substantial seasonal variation. The wave periods are mostly concentrated in a narrow range of 2.6–4 s. Their distribution is almost constant over decades. The role of remote swell is very small. %0 journal article %@ 0027-0644 %A Barcikowska, M., Feser, F., Storch, H.v. %D 2012 %J Monthly Weather Review %N 9 %P 2818-2830 %R doi:10.1175/MWR-D-11-00175.1 %T Usability of best track data in climate statistics in the western North Pacific %U https://doi.org/10.1175/MWR-D-11-00175.1 9 %X Scatterometer-based data used as a reference show that for the tropical storm phase JMA provides more reliable TC intensities than JTWC. Comparisons with aircraft observations indicate that not only homogeneity but also a harmonization and refinement of operational rules controlling intensity estimations should be implemented in all agencies providing BTD. %0 journal article %@ 0930-7575 %A Ibrahim, B., Polcher, J., Karambiri, H., Rockel, B. %D 2012 %J Climate Dynamics %N 6 %P 1287-1302 %R doi:10.1007/s00382-011-1276-x %T Characterization of the rainy season in Burkina Faso and it’s representation by regional climate models %U https://doi.org/10.1007/s00382-011-1276-x 6 %X West African monsoon is one of the most challenging climate components to model. Five regional climate models (RCMs) were run over the West African region with two lateral boundary conditions, ERA-Interim re-analysis and simulations from two general circulation models (GCMs). Two sets of daily rainfall data were generated from these boundary conditions. These simulated rainfall data are analyzed here in comparison to daily rainfall data collected over a network of ten synoptic stations in Burkina Faso from 1990 to 2004. The analyses are based on a description of the rainy season throughout a number of it’s characteristics. It was found that the two sets of rainfall data produced with the two driving data present significant biases. The RCMs generally produce too frequent low rainfall values (between 0.1 and 5 mm/day) and too high extreme rainfalls (more than twice the observed values). The high frequency of low rainfall events in the RCMs induces shorter dry spells at the rainfall thresholds of 0.1–1 mm/day. Altogether, there are large disagreements between the models on the simulate season duration and the annual rainfall amounts but most striking are their differences in representing the distribution of rainfall intensity. It is remarkable that these conclusions are valid whether the RCMs are driven by re-analysis or GCMs. In none of the analyzed rainy season characteristics, a significant improvement of their representation can be found when the RCM is forced by the re-analysis, indicating that these deficiencies are intrinsic to the models. %0 journal article %@ 0003-0007 %A Hemer, M.A., Wang, X.L., Weisse, R., Swail, V.R., and COWCLIP Team %D 2012 %J Bulletin of the American Meteorological Society %P 791-796 %R doi:10.1175/BAMS-D-11-00184.1 %T Advancing wind-waves climate science - The COWCLIP project %U https://doi.org/10.1175/BAMS-D-11-00184.1 %X The Coordinated Ocean Wave Climate Projections (COWCLIP) project has been established with the support of the World Climate Research Programme (WCRP) and the Joint Technical Commission on Oceanography and Marine Meteorology (JCOMM) of the World Meteorological Organization (WMO) and the Intergovernmental Oceanographic Commission (IOC). COWCLIP provides a community derived experimental protocol for studying the role of wind-waves in the coupled climate system. A key recommended objective of COWCLIP is coordination of global wave projections for intercomparison between international research groups, to understand uncertainty within the community ensemble of wave climate projections. These objectives aim to support the climate impacts community, to support coastal impact assessments of climate change which extend beyond the effects of sea-level rise. COWCLIP aims for waves to become a standard component of coupled climate modelling systems, advocating development of coupled atmosphere-wave-ocean GCMs. Not only allowing additional parameters by which to assess the climate system, coupling waves into ocean-atmosphere climate models with more physically representative parameterisations of exchange of momentum, heat and mass across the air-sea interface will enable quantification of wave driven feedbacks in the coupled climate system. %0 journal article %@ 1932-6203 %A Schoo, K.L., Aberle, N., Malzahn, A.M., Boersma, M. %D 2012 %J PLoS One %N 3 %P e33550 %R doi:10.1371/journal.pone.0033550 %T Food Quality Affects Secondary Consumers Even at Low Quantities: An Experimental Test with Larval European Lobster %U https://doi.org/10.1371/journal.pone.0033550 3 %X The issues of food quality and food quantity are crucial for trophic interactions. Although most research has focussed on the primary producer – herbivore link, recent studies have shown that quality effects at the bottom of the food web propagate to higher trophic levels. Negative effects of poor food quality have almost exclusively been demonstrated at higher food quantities. Whether these negative effects have the same impact at low food availability in situations where the majority if not all of the resources are channelled into routine metabolism, is under debate. In this study a tri-trophic food chain was designed, consisting of the algae Rhodomonas salina, the copepod Acartia tonsa and freshly hatched larvae of the European lobster Homarus gammarus. The lobster larvae were presented with food of two different qualities (C:P ratios) and four different quantities to investigate the combined effects of food quality and quantity. Our results show that the quality of food has an impact on the condition of lobster larvae even at very low food quantities. Food with a lower C:P content resulted in higher condition of the lobster larvae regardless of the quantity of food. These interacting effects of food quality and food quantity can have far reaching consequences for ecosystem productivity. %0 journal article %@ 0941-2948 %A Lindenberg, J., Mengelkamp, H.-T., Rosenhagen, G. %D 2012 %J Meteorologische Zeitschrift %N 1 %P 99-106 %R doi:10.1127/0941-2948/2012/0131 %T Representativity of near surface wind measurements from coastal stations at the German Bight %U https://doi.org/10.1127/0941-2948/2012/0131 1 %X The public interest in wind climate is increasing because of the continuously growing wind energy sector on the one hand and the large effects of recent extraordinary events in the storm climate like the severe storm Kyrill in 2007 on the other. Therefore, there is a high demand for high quality wind data for investigations into the regional wind climate. Even though the sensitivity of the measurand wind and the related difficulties in obtaining homogenous series of measurements are well-known (Wieringa, 1996; WMO, 2008), near surface wind measurements are nevertheless often used as representatives for the regional wind climate. In the offshore wind energy sector it is a common approach to extrapolate data from coastal stations for estimating the wind conditions at prospective offshore sites. To evaluate the reliability of such coastal wind data series, measurements from five near coastal weather stations over the same 53 year period were collected. Comparisons to observations of a different measuring net were conducted to investigate the influence of changes in the sampling frequency. Intercomparisons between the yearly means and 99th percentiles of the five stations show a low similarity. This emphasizes that wind speed measurements are strongly influenced by the particular environment. To focus on the effect of station relocations, a case study for Helgoland, the data of which are often used as a proxy for the regional wind climate in the German Bight, is conducted including a valuation of the effect of the station relocation on wind power statistics. %0 journal article %@ 1438-387X %A Puls, W., Bernem, K.-H.van, Eppel, D., Kapitza, H., Pleskachevsky, A., Riethmueller, R., Vaessen, B. %D 2012 %J Helgoland Marine Research %N 6 %P 345-361 %R doi:10.1007/s10152-011-0275-y %T Prediction of benthic community structure from environmental variables in a soft-sediment tidal basin (North Sea) %U https://doi.org/10.1007/s10152-011-0275-y 6 %X The relationship between benthos data and environmental data in 308 samples collected from the intertidal zone of the Hörnum tidal basin (German Wadden Sea) was analyzed. The environmental variables were current velocity, wave action, emersion time (all of which were obtained from a 2-year simulation with a numerical model) and four sediment grain-size parameters. A grouping of sample stations into five benthos clusters showed a large-scale (>1 km) zoning of benthic assemblages on the tidal flats. The zoning varied with the distance from the shore. Three sample applications were examined to test the predictability of the benthic community structure based on environmental variables. In each application, the dataset was spatially partitioned into a training set and a test set. Predictions of benthic community structure in the test sets were attempted using a multinomial logistic regression model. Applying hydrodynamic predictors, the model performed significantly better than it did when sediment predictors were applied. The accuracy of model predictions, given by Cohen’s kappa, varied between 0.14 and 0.49. The model results were consistent with independently attained evidence of the important role of physical factors in Wadden Sea tidal flat ecology. %0 journal article %@ 1748-9326 %A Feser, F., Barcikowska, M. %D 2012 %J Environmental Research Letters %N 1 %P 014024 %R doi:10.1088/1748-9326/7/1/014024 %T The influence of spectral nudging on typhoon formation in regional climate models %U https://doi.org/10.1088/1748-9326/7/1/014024 1 %X The aim of this study is to show the influence that this method has on the formation of tropical cyclones (TC) in regional climate models. Two ensemble simulations (each with five simulations) were computed for Southeast Asia and the Northwestern Pacific for the typhoon season 2004, one with spectral nudging and one without. First of all, spectral nudging reduced the overall TC number by about a factor of 2. But the number of tracks which are similar to observed best track data (BTD) was greatly increased. Also, spatial track density patterns were found to be more similar when using spectral nudging. The tracks merge after a short time for the spectral nudging simulations and then follow the BTD closely; for the no nudge cases the similarity is greatly reduced. A comparison of seasonal precipitation, geopotential height, and temperature fields at several height levels with observations and reanalysis data showed overall a smaller ensemble spread, higher pattern correlations and reduced root mean square errors and biases for the spectral nudged simulations. Vertical temperature profiles for selected TCs indicate that spectral nudging is not inhibiting TC development at higher levels. Both the Madden–Julian Oscillation and monsoonal precipitation are reproduced realistically by the regional model, with results slightly closer to reanalysis data for the spectral nudged simulations. On the basis of this regional climate model hindcast study of a single typhoon season, spectral nudging seems to be favourable since it has mostly positive effects on typhoon formation, location and general circulation patterns in the generation areas of TCs. %0 journal article %@ 1470-160X %A Busch, M., La Notte, A., Laporte, V., Erhard, M. %D 2012 %J Ecological Indicators %P 89-103 %R doi:10.1016/j.ecolind.2011.11.010 %T Potentials of quantitative and qualitative approaches to assessing ecosystem services %U https://doi.org/10.1016/j.ecolind.2011.11.010 %X Quantitative and qualitative approaches to assessing and valuing ecosystem services have been compared using case studies from Italy and Germany. This paper describes and analyzes two different methods of applying an ecosystem service approach and discusses their relative strengths, shortcomings and peculiarities. This allows the conditions to be identified that best support the application of one or other of these methods. Suggestions are offered on how to integrate both methodologies in order to improve the implementation of an ecosystem service approach in decision-making processes. %0 journal article %@ 1352-2310 %A Vautard, R., Moran, M.D., Solazzo, E., Gilliam, R.C., Matthias, V., Bianconi, R., Chemel, C., Ferreira, J., Geyer, B., Hansen, A.B., Jericevic, A., Prank, M., Segers, A., Silver, J.D., Werhahn, J., Wolke, R., Rao, S.T., Galmarini, S. %D 2012 %J Atmospheric Environment %P 15-37 %R doi:10.1016/j.atmosenv.2011.10.065 %T Evaluation of the meteorological forcing used for the Air Quality Model Evaluation International Initiative (AQMEII) air quality simulations %U https://doi.org/10.1016/j.atmosenv.2011.10.065 %X Accurate regional air pollution simulation relies strongly on the accuracy of the mesoscale meteorological simulation used to drive the air quality model. The framework of the Air Quality Model Evaluation International Initiative (AQMEII), which involved a large international community of modeling groups in Europe and North America, offered a unique opportunity to evaluate the skill of mesoscale meteorological models for two continents for the same period. More than 20 groups worldwide participated in AQMEII, using several meteorological and chemical transport models with different configurations. The evaluation has been performed over a full year (2006) for both continents. The focus for this particular evaluation was meteorological parameters relevant to air quality processes such as transport and mixing, chemistry, and surface fluxes. The unprecedented scale of the exercise (one year, two continents) allowed us to examine the general characteristics of meteorological models’ skill and uncertainty. In particular, we found that there was a large variability between models or even model versions in predicting key parameters such as surface shortwave radiation. We also found several systematic model biases such as wind speed overestimations, particularly during stable conditions. We conclude that major challenges still remain in the simulation of meteorology, such as nighttime meteorology and cloud/radiation processes, for air quality simulation. %0 journal article %@ 1814-9324 %A Gomez-Navarro, J.J., Montavez, J.P., Jimenez-Guerrero, P., Jerez, S., Lorente-Plazas, R., Gonzalez-Rouco, J.F., Zorita, E. %D 2012 %J Climate of the Past %N 1 %P 25-36 %R doi:10.5194/cp-8-25-2012 %T Internal and external variability in regional simulations of the Iberian Peninsula climate over the last millennium %U https://doi.org/10.5194/cp-8-25-2012 1 %X In this study we analyse the role of internal variability in regional climate simulations through a comparison of two regional paleoclimate simulations for the last millennium. They share the same external forcings and model configuration, differing only in the initial condition used to run the driving global model simulation. A comparison of these simulations allows us to study the role of internal variability in climate models at regional scales, and how it affects the long-term evolution of climate variables such as temperature and precipitation. The results indicate that, although temperature is homogeneously sensitive to the effect of external forcings, the evolution of precipitation is more strongly governed by random unpredictable internal dynamics. There are, however, some areas where the role of internal variability is lower than expected, allowing precipitation to respond to the external forcings. In this respect, we explore the underlying physical mechanisms responsible for it. This study identifies areas, depending on the season, in which a direct comparison between model simulations of precipitation and climate reconstructions would be meaningful, but also other areas where good agreement between them should not be expected even if both are perfect. %0 journal article %@ 0171-8630 %A Wirtz, K.W. %D 2012 %J Marine Ecology - Progress Series %P 1-12 %R doi:10.3354/meps09502 %T Who is eating whom? Morphology and feeding type determine the size relation between planktonic predators and their ideal prey %U https://doi.org/10.3354/meps09502 %X Body size determines the position of organisms in plankton food-webs. The mass or diameter ratio between predators and their optimal prey is therefore a central element of size-based models in their attempt to link consumer groups across trophic levels. Despite a renaissance of size-based approaches in plankton ecology, however, this relation still lacks a generic and also mechanistically sound formulation. An empirically derived constant value of this ratio can not describe the wide scatter in optimal prey diameter for specific predator size classes, especially in the mesozooplankton range. In this study, I propose that a given morpho-metric ratio between feeding related apparatus and total body volume decreases when predator size increases. This ratio decrease is due to the additional need of structural components in larger organisms for maintaining intra-body transport. Non-isometric scaling results in a non-linear dependency of optimal prey size on predator diameter. This dependency defines an average relation which enables the quantitative definition of feeding mode. This new trait variable explains a component of the variability in optimal prey diameter that is independent from predator diameter. Feeding mode as a trait can be interpreted as activity during grazing, mostly in terms of speed regulation in swimming or in feeding current generation. Feeding mode, in concert with the classical trait predator size, accurately determines optimal prey size. This is extensively tested using literature data for the entire plankton domain. The theory predicts an increasing feeding activity in larger consumer species. It elucidates how successional shifts in the composition of zooplankton communities are linked to weakly coupled changes in mean body size and feeding mode. %0 journal article %@ 0013-936X %A Cai, M., Zhao, Z, Yin, Z., Ahrens, L., Huang, P., Cai, Mg., Yang, H., He, J., Sturm, R., Ebinghaus, R., Xie, Z. %D 2012 %J Environmental Science and Technology %N 2 %P 661-668 %R doi:10.1021/es2026278 %T Occurrence of perfluoroalkyl compounds in surface waters from the North Pacific to the Arctic Ocean %U https://doi.org/10.1021/es2026278 2 %X Perfluoroalkyl compounds (PFCs) were determined in 22 surface water samples (39−76°N) and three sea ice core and snow samples (77−87°N) collected from North Pacific to the Arctic Ocean during the 4th Chinese Arctic Expedition in 2010. Geographically, the average concentration of ∑PFC in surface water samples were 560 ± 170 pg L-1 for the Northwest Pacific Ocean, 500 ± 170 pg L-1 for the Arctic Ocean, and 340 ± 130 pg L-1 for the Bering Sea, respectively. The perfluoroalkyl carboxylates (PFCAs) were the dominant PFC class in the water samples, however, the spatial pattern of PFCs varied. The C5, C7 and C8 PFCAs (i.e., perfluoropentanoate (PFPA), perfluoroheptanoate (PFHpA), and perfluorooctanoate (PFOA)) were the dominant PFCs in the Northwest Pacific Ocean while in the Bering Sea the PFPA dominated. The changing in the pattern and concentrations in Pacific Ocean indicate that the PFCs in surface water were influenced by sources from the East-Asian (such as Japan and China) and North American coast, and dilution effect during their transport to the Arctic. The presence of PFCs in the snow and ice core samples indicates an atmospheric deposition of PFCs in the Arctic. The elevated PFC concentration in the Arctic Ocean shows that the ice melting had an impact on the PFC levels and distribution. In addition, the C4 and C5 PFCAs (i.e., perfluorobutanoate (PFBA), PFPA) became the dominant PFCs in the Arctic Ocean indicating that PFBA is a marker for sea ice melting as the source of exposure. %0 journal article %@ 0930-7575 %A Barkhordarian, A., Bhend, J., Storch, H.v. %D 2012 %J Climate Dynamics %N 9-10 %P 1695-1702 %R doi:10.1007/s00382-011-1060-y %T Consistency of observed near surface temperature trends with climate change projections over the Mediterranean region %U https://doi.org/10.1007/s00382-011-1060-y 9-10 %X We examine the possibility that anthropogenic forcing (Greenhouse gases and Sulfate aerosols, GS) is a plausible explanation for the observed near-surface temperature trends over the Mediterranean area. For this purpose, we compare annual and seasonal observed trends in near-surface temperature over the period from 1980 to 2009 with the response to GS forcing estimated from 23 models derived from CMIP3 database. We find that there is less than a 5% chance that natural (internal) variability is responsible for the observed annual and seasonal area-mean warming except in winter. Using additionally two pattern similarity statistics, pattern correlation and regression, we find that the large-scale component (spatial-mean) of the GS signal is detectable (at 2.5% level) in all seasons except in winter. In contrast, we fail to detect the small-scale component (spatial anomalies about the mean) of GS signal in observed trend patterns. Further, we find that the recent trends are significantly (at 2.5% level) consistent with all the 23 GS patterns, except in summer and spring, when 9 and 5 models respectively underestimate the observed warming. Thus, we conclude that GS forcing is a plausible explanation for the observed warming in the Mediterranean region. Consistency of observed trends with climate change projections indicates that present trends may be understood of what will come more so in the future, allowing for a better communication of the societal challenges to meet in the future. %0 journal article %@ 0269-7491 %A Cai, M., Zhao, Z., Yang, H., Yin, Z., Hong, Q., Sturm, R., Ebinghaus, R., Ahrens, L., He, J., Xie, Z. %D 2012 %J Environmental Pollution %P 162-169 %R doi:10.1016/j.envpol.2011.09.045 %T Spatial distribution of per- and polyfluoroalkyl compounds in coastal waters from the East to South China Sea %U https://doi.org/10.1016/j.envpol.2011.09.045 %X The spatial distribution of per- and polyfluoroalkyl compounds (PFCs) were investigated in coastal waters collected onboard research vessel Snow Dragon from the East to South China Sea in 2010. All samples were prepared by solid-phase extraction and analyzed using high performance liquid chromatography/negative electrospray ionization-tandem mass spectrometry (HPLC/(−)ESI-MS/MS). Concentrations of 9 PFCs, including C4 and C8 (PFBS, PFOS) perfluoroalkyl sulfonate (PFSAs), C5–C9 and C13 (PFPA, PFHxA, PFHpA, PFOA, PFNA, PFTriDA) perfluoroalkyl carboxylates (PFCAs), and N-ethyl perfluorooctane sulfonamide (EtFOSA) were quantified. The ΣPFC concentrations ranged from 133 pg/L to 3320 pg/L, with PFOA (37.5–1541 pg/L), PFBS (23.0–941 pg/L) and PFHpA (0–422 pg/L) as dominant compounds. Concentrations of PFCs were greater in coastal waters along Shanghai, Ningbo, Taizhou, Xiamen and along coastal cities of the Guangdong province compared to less populated areas along the east Chinese coast. Additionally, the comparison with other seawater PFC measurements showed lower levels in this study. %0 journal article %@ 1352-2310 %A Matthias, V., Aulinger, A., Bieser, J., Cuesta, J., Geyer, B., Langmann, B., Serikov, I., Mattis, I., Minikin, A., Mona, L., Quante, M., Schumann, U., Weinzierl, B. %D 2012 %J Atmospheric Environment %P 184-194 %R doi:10.1016/j.atmosenv.2011.06.077 %T The ash dispersion over Europe during the Eyjafjallajökull eruption – Comparison of CMAQ simulations to remote sensing and air-borne in-situ observations %U https://doi.org/10.1016/j.atmosenv.2011.06.077 %X The dispersion of volcanic ash over Europe after the outbreak of the Eyjafjallajökull on Iceland on 14 April 2010 has been simulated with a conventional three-dimensional Eulerian chemistry transport model system, the Community Multiscale Air Quality (CMAQ) model. Four different emission scenarios representing the lower and upper bounds of the emission height and intensity were considered. The atmospheric ash concentrations turned out to be highly variable in time and space. The model results were compared to three different kinds of observations: Aeronet aerosol optical depth (AOD) measurements, Earlinet aerosol extinction profiles and in-situ observations of the ash concentration by means of optical particle counters aboard the DLR Falcon aircraft. The model was able to reproduce observed AOD values and atmospheric ash concentrations. Best agreement was achieved for lower emission heights and a fraction of 2% transportable ash in the total volcanic emissions. The complex vertical structure of the volcanic ash layers in the free troposphere could not be simulated. Compared to the observations, the model tends to show vertically more extended, homogeneous aerosol layers. This is caused by a poor vertical resolution of the model at higher altitudes and a lack of information about the vertical distribution of the volcanic emissions. Only a combination of quickly available observations of the volcanic ash cloud and atmospheric transport models can give a comprehensive picture of ash concentrations in the atmosphere. %0 journal article %@ 0272-7714 %A Swaney, D.P., Humborg, C., Emeis, K., Kannen, A., Silvert, W., Tett, P., Pastres, R., Solidoro, C., Yamamuro, M., Henocque, Y., Nicholls, R. %D 2012 %J Estuarine, Coastal and Shelf Science %P 9-21 %R doi:10.1016/j.ecss.2011.04.010 %T Five critical questions of scale for the coastal zone %U https://doi.org/10.1016/j.ecss.2011.04.010 %X These questions do not have straightforward answers. There is no single “scale” for coastal ecosystems; their multiscale nature complicates our understanding and management of them. Coastal ecosystems depend on their watersheds as well as spatially-diffuse “footprints” associated with modern trade and material flows. Change occurs both rapidly and slowly on human time scales, and observing and responding to changes in coastal environments is a fundamental challenge. Apparently small human decisions collectively have potentially enormous consequences for coastal environmental quality, and our success in managing the effects of these decisions will determine the quality of life in the coastal zone in the 21st century and beyond. Vigilant monitoring, creative synthesis of information, and continued research will be necessary to properly understand and govern our coastal environments into the future. %0 journal article %@ 0964-5691 %A Weisse, R., Storch, H.v., Niemeyer, H.D., Knaack, H. %D 2012 %J Ocean and Coastal Management %P 58-68 %R doi:10.1016/j.ocecoaman.2011.09.005 %T Changing North Sea storm surge climate: An increasing hazard? %U https://doi.org/10.1016/j.ocecoaman.2011.09.005 %X Extreme sea levels provide a substantial hazard for low lying coastal areas in the Southern North Sea. They are caused by a combination of different factors such as high astronomical tides, a large-scale rise of the sea surface caused by high wind speeds and low atmospheric pressure (usually referred to as storm surges), or extreme wind-generated waves (sea states) caused by high wind speeds in atmospheric low pressure systems; that is extra-tropical storms. Long-term changes in any of these factors may substantially alter the hazard associated with extreme sea levels. Moreover, any long-term change in mean sea level such as observed over the past 100 years or as associated with future anthropogenic climate change will have an impact as it shifts the entire distribution of sea levels towards higher values; that is, it changes the baseline upon which storm induced sea levels have to be added. Moreover, in shallow waters non-linear interaction effects may occur. Here we review the present knowledge about long-term changes in any of these factors. We show that storm activity in the area underwent considerable variations on time scales of decades and longer, but that no clear long-term trend could be identified. Similar findings are obtained for long-term changes in the storm surge and wave climate. Mean sea level has increased in the Southern North Sea over the past centuries. Correspondingly an increase in extreme sea levels is found. For the future most projections point towards a moderate increase in storm activity in the area with corresponding changes in storm surge and wave climate. These changes will add to the expected future increase in mean sea level, leading to an increased hazard from extreme sea levels. The latter may have consequences for safety, especially in the low lying coastal areas in the Southern North Sea. Consequences for coastal protection and alternative strategies are discussed. %0 journal article %@ 0049-6979 %A Bieser, J., Aulinger, A., Matthias, V., Quante, M. %D 2012 %J Water, Air, and Soil Pollution %N 3 %P 1393-1414 %R doi:10.1007/s11270-011-0953-z %T Impact of Emission Reductions between 1980 and 2020 on Atmospheric Benzo[a]pyrene Concentrations over Europe %U https://doi.org/10.1007/s11270-011-0953-z 3 %X pollutants which have an impact on the formation of ozone. %0 journal article %@ 1537-744X %A Barkhordarian, A. %D 2012 %J The Scientific World Journal %P 525303 %R doi:10.1100/2012/525303 %T Investigating the Influence of Anthropogenic Forcing on ObservedMean and Extreme Sea Level Pressure Trends over the Mediterranean Region %U https://doi.org/10.1100/2012/525303 %X forcing, which is not GS forcing. %0 journal article %@ 1708-3087 %A Burkhard, B., Gee, K. %D 2012 %J Ecology and Society %N 4 %P 32 %R doi:10.5751/ES-05207-170432 %T Establishing the Resilience of a Coastal-marine Social-ecological System to the Installation of Offshore Wind Farms %U https://doi.org/10.5751/ES-05207-170432 4 %X Offshore wind farming is a contentious new form of sea use and a prominent driver of change across Europe. Drawing on the results of the research program Zukunft Küste - Coastal Futures, this contribution considers the resilience of the social-ecological system to the introduction of offshore wind farming in a northern German case study region. We do so by focusing on regime shifts and cross-scale effects, described through the concepts of adaptive cycles and ecosystem services. Offshore wind farming is shown to lead to a potential slow regime shift in the marine ecosystem, as well as a more rapid regime shift in the seascape. These shifts lead to changes in the available ecosystem services and conflicts between new and traditional sea and seascape values. We then explore the impact of these changes on the socioeconomic system on the coast. Against the background of the system’s current state and constraints, we argue this impact could be creative and innovative, but this trajectory depends on an internal socio-political shift and willingness to change. %0 journal article %@ 1758-678X %A Esper, J., Frank, D.C., Timonen, M., Zorita, E., Wilson, R.J.S., Luterbacher, J., Holzkaemper, S., Fischer, N., Wagner, S., Nievergelt, D., Verstege, A., Buentgen, U. %D 2012 %J Nature Climate Change %P 862-866 %R doi:10.1038/nclimate1589 %T Orbital forcing of tree-ring data %U https://doi.org/10.1038/nclimate1589 %X Solar insolation changes, resulting from long-term oscillations of orbital configurations1, are an important driver of Holocene climate2, 3. The forcing is substantial over the past 2,000 years, up to four times as large as the 1.6 W m−2 net anthropogenic forcing since 1750 (ref. 4), but the trend varies considerably over time, space and with season5. Using numerous high-latitude proxy records, slow orbital changes have recently been shown6 to gradually force boreal summer temperature cooling over the common era. Here, we present new evidence based on maximum latewood density data from northern Scandinavia, indicating that this cooling trend was stronger (−0.31 °C per 1,000 years, ±0.03 °C) than previously reported, and demonstrate that this signature is missing in published tree-ring proxy records. The long-term trend now revealed in maximum latewood density data is in line with coupled general circulation models7, 8 indicating albedo-driven feedback mechanisms and substantial summer cooling over the past two millennia in northern boreal and Arctic latitudes. These findings, together with the missing orbital signature in published dendrochronological records, suggest that large-scale near-surface air-temperature reconstructions9, 10, 11, 12, 13 relying on tree-ring data may underestimate pre-instrumental temperatures including warmth during Medieval and Roman times. %0 journal article %@ 0948-3055 %A Sperling, M., Giebel, H.-A., Rink, B., Grayek, S., Staneva, J., Stanev, E.V., Simon, M. %D 2012 %J Aquatic Microbial Ecology %N 1 %P 25-34 %R doi:10.3354/ame01580 %T Differential effects of hydrographic and biogeochemical properties on the SAR11 clade and Roseobacter RCA cluster in the North Sea %U https://doi.org/10.3354/ame01580 1 %X The SAR11 clade and the Roseobacter clade affiliated (RCA) cluster belong to the most prominent bacterioplankton groups in temperate to polar seas. Despite some insights into biological controls of both lineages, little is known about environmental, hydrographic and biogeochemical controls. Therefore, we assessed the abundance of both lineages using quantitative PCR in the southern North Sea, subjected them to a multiple linear regression analysis and related their occurrence to current patterns by backtracking the water masses found at individual stations for the preceding 24 to 27 d. SAR11 constituted <1 to 47% of total bacterial 16S rRNA genes. The abundance of this clade was inversely correlated to the salinity change of the water masses at the stations, indicating a preference for stable and presumably nutrient depleted waters. The RCA cluster constituted <1 to 5% of total bacterial 16S rRNA genes but did not exhibit any correlation to hydrographic properties. However, a multiple linear regression analysis showed that the RCA cluster was significantly correlated to a suite of biogeochemical parameters, bacterial abundance, concentrations of chlorophyll a, particulate organic carbon and suspended particulate matter and salinity changes, explaining 94.3% of the variability of the RCA data. These results show that backtracking water masses and relating them to bacterioplankton populations aids in the understanding of the growth dynamics of specific bacterioplankton populations and sheds new light on why high abundances of the SAR11 clade are usually found in stratified water masses. %0 journal article %@ 0941-2948 %A Hermans, A., Ament, F., Geyer, B., Matthias, V., Quante, M., Rockel, B. %D 2012 %J Meteorologische Zeitschrift %N 5 %P 487-502 %R doi:10.1127/0941-2948/2012/0326 %T Evaluation of Humidity, Clouds and Precipitation in COSMO-CLM and MM5 over Germany %U https://doi.org/10.1127/0941-2948/2012/0326 5 %X The knowledge of uncertainties resulting from simulations of the hydrological cycle in meteorological models is crucial for the interpretation of model results. In order to gain confidence in statements about future changes, it is necessary to assess the model skill in the representation of the hydrological cycle. This study focuses on the evaluation of the atmospheric part of the hydrological cycle in two mesoscale meteorological models, MM5 and COSMO-CLM (CCLM). By using high resolution observations from the General Observation Period (GOP) performed in the German Priority Program on Quantitative Precipitation Forecasting, the representation of integrated water vapour, total cloud cover and precipitation is evaluated. Model runs were performed for the period of 2007 and 2008 within the model domain covering Germany with a spatial resolution of about 18 km. Both models are forced by reanalysis data of the National Centers for Environmental Prediction (NCEP1). The performance of the models is evaluated concerning their annual cycles, space-time structures and diurnal cycles of the model simulations. Error structures of the three considered key variables are very different: Concerning integrated water vapour, errors are mainly due to the large scale forcing in both models. MM5 exhibits a systematic wet bias. In contrast, errors in predicted total cloud cover are dominated by shortcomings of the parametrizations concerning convection and clouds. Precipitation errors are influenced by the orography and depend on the convection parametrization. Interestingly, the wet bias in integrated water vapour of MM5 does not result in a positive precipitation bias. %0 journal article %@ 2190-5754 %A Meinke, I., Reckermann, M. %D 2012 %J Meer & Küste %N 3 %P 4-5 %T Klimawandel an der Ostseeküste : Neues zum Forschungsstand %U 3 %X Klimawandel findet statt, und kann sich in Zukunft beschleunigen, auch an der Ostseeküste. Dies ist der Konsens aus jahrzehntelangen Forschungsaktivitäten im gesamten Ostseeraum. Welche Änderungen gibt es in unserer Region, welche werden erwartet und wie wirken sie sich auf die Umwelt aus? Der Ostseeraum hat sich im vergangenen Jahrhundert bereits um etwa 0,85°C erwärmt. Damit liegt die Erwärmung leicht über dem weltweiten Durchschnitt. Die Veränderungen sind jedoch regional unterschiedlich: So betrug der Anstieg der Lufttemperatur im Norden etwa 1°C, in der südlichen Ostsee rund 0,7°C. In einem Jahr gibt es heute an der deutschen Ostseeküste etwa zehn Sommertage (wärmer als 25°C) mehr und etwa 20 Frosttage weniger als in den 1950er Jahren. %0 journal article %@ 0930-7575 %A Cavicchia, L., Storch, H.v. %D 2012 %J Climate Dynamics %N 9-10 %P 2273-2290 %R doi:10.1007/s00382-011-1220-0 %T The simulation of medicanes in a high-resolution regional climate model %U https://doi.org/10.1007/s00382-011-1220-0 9-10 %X Medicanes, strong mesoscale cyclones with tropical-like features, develop occasionally over the Mediterranean Sea. Due to the scarcity of observations over sea and the coarse resolution of the long-term reanalysis datasets, it is difficult to study systematically the multidecadal statistics of sub-synoptic medicanes. Our goal is to assess the long-term variability and trends of medicanes, obtaining a long-term climatology through dynamical downscaling of the NCEP/NCAR reanalysis data. In this paper, we examine the robustness of this method and investigate the value added for the study of medicanes. To do so, we performed several climate mode simulations with a high resolution regional atmospheric model (CCLM) for a number of test cases described in the literature. We find that the medicanes are formed in the simulations, with deeper pressures and stronger winds than in the driving global NCEP reanalysis. The tracks are adequately reproduced. We conclude that our methodology is suitable for constructing multi-decadal statistics and scenarios of current and possible future medicane activities. %0 journal article %@ 0264-3707 %A aus der Beek, T., Menzel, L., Rietbroek, R., Fenoglio-Marc, L., Grayek, S., Becker, M., Kusche, J., Stanev, E.V. %D 2012 %J Journal of Geodynamics %P 157-167 %R doi:10.1016/j.jog.2011.11.011 %T Modeling the water resources of the Black and Mediterranean Sea river basins and their impact on regional mass changes %U https://doi.org/10.1016/j.jog.2011.11.011 %X For the first time, a dedicated release of the hydrology and water use model WaterGAP3, has been developed to spatially explicit calculate hydrological fluxes within river basins draining into the Mediterranean and Black Sea. The main differences between the new regional version of the global WaterGAP3 model and the previously applied global version WaterGAP2 can be found in the spatial resolution, snow modeling, and water use modeling. Comparison with observations shows that WaterGAP3 features a more realistic representation of modeled river runoff and inflow into both seas. WaterGAP3 generates more inflow to both seas than WaterGAP2. In the WaterGAP3 simulation, contributions to the total runoff into the Black Sea from individual discharge regions show in general a good agreement to climatology derived runoff, but lesser importance of Georgian rivers for the basin's water. After the successful model validation WaterGAP3 has been applied to correct estimates of seawater mass derived from the GRACE gravity mission and to account for freshwater inflow into both basins. The performance of the WaterGAP3 regional solution has been evaluated by comparing the seawater mass derived from GRACE corrected for the leakage of continental hydrology, to an independent estimate derived from steric-corrected satellite altimetry with steric correction from regional oceanographic models. The agreement is higher in the Mediterranean Sea than in the Black Sea. Results using WaterGAP3 and WaterGAP2 are not significantly different. However the agreement with the altimetry-derived results is higher using WaterGAP2, due to the smaller annual amplitude of the continental hydrology leakage from WaterGAP3. We conclude that the regional model WaterGAP3 is capable of realistically quantifying water mass variation in the region, further developments have been identified. %0 journal article %@ 0029-8549 %A Wirtz, K.W. %D 2012 %J Oecologia %N 4 %P 879-894 %R doi:10.1007/s00442-012-2257-4 %T Intermittency in processing explains the diversity and shape of functional grazing responses %U https://doi.org/10.1007/s00442-012-2257-4 4 %X Central to theoretical studies of trophic interactions is the formulation of the consumer response to varying food availability. Response functions, however, are only rarely derived in mechanistic ways. As a consequence, the uncertainty in the functional representation of feeding remains large, as, e.g., evident from the ongoing debate on the usage of Ivlev, or Holling type I, II, and III functions in aquatic ecosystem models. Here, I refer to the work of Sjöberg in Ecol Model 10:215–225 (1980) who proposed to apply elements of the queuing theory developed in operational research to plankton–plankton interactions. Within this frame, food item processing is subdivided into two major stages which may operate with variable synchronicity. Asynchronous phasing of the two stages enhances the probability of long total processing times. This phenomenon is here termed feeding intermittency. Intermittency is assumed to determine the functional form of grazing kinetics, for which a novel grazing function containing a “shape” parameter is derived. Using this function, I evaluate the hypotheses that intermittency is influenced by (1) patchiness in the prey field (e.g., related to turbulence), and (2) the ratio of actual prey size to optimal prey size. Evidence for the first hypothesis arises from explaining reported variations in clearance rates of Acartia tonsa under different turbulence regimes. Further model applications to ingestion data for rotifers, copepods, and ciliates support the view that an increasing food size enhances intermittency and, this way, affects functional grazing responses. In the application to ciliate grazing, a possible prey density effect appears, possibly due to an intermittent activation of a feeding sub-stage. Queueing theory offers mechanistic explanations for transitions between Holling I-, II-, and Ivlev-type grazing. In doing so for variable prey size ratios, it may also refine size-based ecosystem models which are increasingly emerging in plankton ecology. %0 journal article %@ 1814-9324 %A Wagner, S., Fast, I., Kaspar, F. %D 2012 %J Climate of the Past %N 5 %P 1599-1620 %R doi:10.5194/cp-8-1599-2012 %T Comparison of 20th century and pre-industrial climate over South America in regional model simulations %U https://doi.org/10.5194/cp-8-1599-2012 5 %X Our results indicate that besides the direct effect of greenhouse gas changes, large-scale changes in atmospheric circulation and sea surface temperatures also exert an influence on temperature and precipitation changes in southern South America. These combined changes in turn affect the relationship between climate and atmospheric circulation between PD and PI times and should be considered for the statistical reconstruction of climate indices calibrated within present-day climate data. %0 journal article %@ 1814-9324 %A Schenk, F., Zorita, E. %D 2012 %J Climate of the Past %N 5 %P 1681-1703 %R doi:10.5194/cp-8-1681-2012 %T Reconstruction of high resolution atmospheric fields for Northern Europe using analog-upscaling %U https://doi.org/10.5194/cp-8-1681-2012 5 %X Different settings of the AM are evaluated in this study for the period 1958–2007 to estimate the robustness of the reconstruction and its ability to replicate high and low-frequency variability, realistic probability distributions and extremes of different meteorological variables. It is shown that the AM can realistically reconstruct variables with a strong physical link to daily sea-level pressure on both a daily and monthly scale. However, to reconstruct low-frequency decadal and longer temperature variations, additional monthly mean station temperature as predictor is required. Our results suggest that the AM is a suitable upscaling tool to predict daily fields taken from regional climate simulations based on sparse historical station data. %0 journal article %@ 0094-8276 %A Barkhordarian, A., Storch, H.v., Zorita, E. %D 2012 %J Geophysical Research Letters %P L19706 %R doi:10.1029/2012GL053026 %T Anthropogenic forcing is a plausible explanation for the observed surface specific humidity trends over the Mediterranean area %U https://doi.org/10.1029/2012GL053026 %X We investigate whether the observed surface specific humidity (q) trends over the Mediterranean region in the period 1974–2003 are consistent with climate model (CMIP3, CMIP5) simulations of q in response to anthropogenic forcing (Greenhouse gas and sulphate aerosols). The natural (internal) variability is estimated using 6,000-year of pre-industrial control simulations. With the exception of winter, the increases in annual and seasonal q over this region are very unlikely (with less than 1%chance) due to natural (internal) variability or natural forcing alone. Using several climate models and ensemble means, we demonstrate that the large-scale component (spatial-mean trend) of the anthropogenic forcing is detectable (at 1% level) in the annual and seasonal trends of q (except winter). However, the smaller-scale component (spatial anomalies about the mean trend) of the anthropogenic signal is detectable only in warm seasons (spring and summer). We further show that the spread of projected trends based on the A1B scenario derived from 13 CMIP3 models encompasses the observed area-averaged trend in q. This may imply that the observed trends of surface humidity, which is an important factor in human thermal comfort, serves as an illustration of plausible future expected change in the region. %0 journal article %@ 1616-7341 %A Stanev, E.V., Kandilarov, R. %D 2012 %J Ocean Dynamics %N 4 %P 533-553 %R doi:10.1007/s10236-012-0520-1 %T Sediment dynamics in the Black Sea: numerical modelling and remote sensing observations %U https://doi.org/10.1007/s10236-012-0520-1 4 %X with the specific shape of Black Sea topography, and the largest depositions are observed in the area of continental slope. %0 journal article %@ 1616-7341 %A Lu, X., Soomere, T., Stanev, E.V., Murawski, J. %D 2012 %J Ocean Dynamics %N 6 %P 815-829 %R doi:10.1007/s10236-012-0532-x %T Identification of the environmentally safe fairway in the South-Western Baltic Sea and Kattegat %U https://doi.org/10.1007/s10236-012-0532-x 6 %X Application of the preventive techniques for the optimisation of fairways in the south-western Baltic Sea and the Kattegat in terms of protection of the coastal regions against current-driven surface transport of adverse impacts released from vessels is considered. The techniques rely on the quantification of the offshore domains (the points of release of adverse impacts) in terms of their ability to serve as a source of remote, current-driven danger to the nearshore. An approximate solution to this inverse problem of current-driven transport is obtained using statistical analysis of a large pool of Lagrangian trajectories of water particles calculated based on velocity fields from the Denmark’s Meteorological Institute (DMI)/BSH cmod circulation model forced by the DMI-HIRHAM wind fields for 1990–1994. The optimum fairways are identified from the spatial distributions of the probability of hitting the coast and for the time (particle age) it takes for the pollution to reach the coast. In general, the northern side of the Darss Sill area and the western domains of the Kattegat are safer to travel. The largest variations in the patterns of safe areas and the properties of pollution beaching occur owing to the interplay of water inflow and outflow. The gain from the use of the optimum fairways is in the range of 10–30 % in terms of the decrease in the probability of coastal hit within 10 days after pollution release or an increase by about 1–2 days of the time it takes for the hit to occur. %0 journal article %@ 0141-1136 %A He, Y., Stanev, E.V., Yakushev, E., Staneva, J. %D 2012 %J Marine Environmental Research %P 90-102 %R doi:10.1016/j.marenvres.2012.02.007 %T Black Sea biogeochemistry: Response to decadal atmospheric variability during 1960-2000 inferred from numerical modeling %U https://doi.org/10.1016/j.marenvres.2012.02.007 %X the specific time-interval 1960e2000; the corresponding regime shifts were thus associated with the large scale forcing. One such extreme event occurred in 1976 leading to a pronounced shift in the oxygen and hydrogen sulfide state. %0 journal article %@ 1616-7341 %A Albrecht, F., Weisse, R. %D 2012 %J Ocean Dynamics %N 8 %P 1169-1186 %R doi:10.1007/s10236-012-0557-1 %T Pressure effects on past regional sea level trends and variability in the German Bight %U https://doi.org/10.1007/s10236-012-0557-1 8 %X The impact on a large-scale sea level pressure field to the regional mean sea level changes of the German Bight is analysed. A multiple linear regression together with an empirical orthogonal function analysis is used to describe the relationship between the sea level pressure and the regional mean sea level considering the time period 1924–2001. Both, the part of the variability and of the long-term trend that can be associated with changes in the sea level pressure, are investigated. Considering the whole time period, this regression explains 58 % of the variance and 33 % of the long-term trend of the regional mean sea level. The index of agreement between the regression result and the observed time series is 0.82. As a proxy for large-scale mean sea level changes, the mean sea level of the North East Atlantic is subsequently introduced as an additional predictor. This further improves the results. For that case, the regression explains 74 % of the variance and 87 % of the linear trend. The index of agreement rises to 0.92. These results suggest that the sea level pressure mainly accounts for the inter-annual variability and parts of the long-term trend of regional mean sea level in the German Bight while large-scale sea level changes in the North East Atlantic account for another considerable fraction of the observed long-term trend. Sea level pressure effects and the mean sea level of the North East Atlantic provide thus significant contributions to regional sea level rise and variability. When future developments are considered, scenarios for their future long-term trends thus need to be comprised in order to provide reliable estimates of potential future long-term changes of mean sea level in the German Bight. %0 journal article %@ 1017-0839 %A Chen, F., Geyer, B., Zahn, M., Storch, H.v. %D 2012 %J Terrestrial, Atmospheric and Oceanic Sciences: TAO %N 3 %P 291-303 %R doi:10.3319/TAO.2011.11.02.01(A) %T Toward a Multi-Decadal Climatology of North Pacific Polar Lows Employing Dynamical Downscaling %U https://doi.org/10.3319/TAO.2011.11.02.01(A) 3 %X The signatures of all storms emerge in the simulations with additional sub-synoptic details. The tracks of the simulated Polar Lows closely follow the tracks derived from satellite imagery. We conclude that the suggested method is suitable for constructing multi-decade climatologies, including trends and variability, of Polar Lows in the North Pacific by dynamically downscaling NCEP re-analyses. %0 journal article %@ 1558-6073 %A Krauss, W., Storch, H.v. %D 2012 %J Nature and Culture %N 2 %P 213-230 %R doi:10.3167/nc.2012.070206 %T Post-normal Practices between Climate Service and Local Knowledge %U https://doi.org/10.3167/nc.2012.070206 2 %X concept, the article focuses on the friction, on “its openness to change as it rubs up against society” (Hulme 2007). The focus then shifts to local knowledge systems and how they deal with the challenges of a changing climate. In addition to the “extended peer review” as a new option for climate research in a post-normal setup, the authors discuss the possibility of an “extended knowledge basis,” that is, the integration of different forms of climate knowledge with a special focus on regional populations. %0 journal article %@ 1558-6073 %A Krauss, W., Schaefer, M.S., Storch, H.v. %D 2012 %J Nature and Culture %N 2 %P 121-132 %R doi:10.3167/nc.2012.070201 %T Introduction: Postnormal Science and Climate Research %U https://doi.org/10.3167/nc.2012.070201 2 %X No abstract %0 journal article %@ 0264-3707 %A Fenoglio-Marc, L., Rietbroek, R., Grayek, S., Becker, M., Kusche, J., Stanev, E. %D 2012 %J Journal of Geodynamics %P 168-182 %R doi:10.1016/j.jog.2012.04.001 %T Water mass variation in the Mediterranean and Black Seas %U https://doi.org/10.1016/j.jog.2012.04.001 %X The mass-induced sea level variability and the net mass transport between Mediterranean Sea and Black Sea are derived for the interval between August 2002 and July 2008 from satellite-based observations and from model data. We construct in each basin two time series representing the basin mean mass signal in terms of equivalent water height. The first series is obtained from steric-corrected altimetry while the other is deduced from GRACE data corrected for the contamination by continental hydrology. The series show a good agreement in terms of annual and inter-annual signals, which is in line with earlier works, although different model corrections influence the consistency in terms of seasonal signal and trend. %0 journal article %@ 0964-5691 %A Ratter, B.M.W., Gee, K. %D 2012 %J Ocean and Coastal Management %P 127-137 %R doi:10.1016/j.ocecoaman.2012.04.013 %T Heimat – A German concept of regional perception and identity as a basis for coastal management in the Wadden Sea %U https://doi.org/10.1016/j.ocecoaman.2012.04.013 %X The German concept of Heimat is closely related to ideas of place, place attachment and sense of place. Despite its difficult history, it is currently experiencing a renaissance in public interest and also in geographical, ethnological and psychological research. This paper explores the perception of Heimat by residents on the German North Sea coast. It traces the specific values the concept embodies, asking whether these particular values can ultimately be tapped to engage people in the process of preserving and developing their Heimat. Survey results reveal that Heimat is constituted by social values, such as feeling connected to family, friends and the wider community. Heimat is also a distinct place linked to a wide range of intangible values such as the aesthetic value of the seascape or the symbolic values assigned to the sea. Heimat can also be regarded as a practice, as it represents a conscious or subconscious act of putting one's surroundings into meaningful order. Identification with Heimat is strong, and there is demonstrable willingness to become involved in preserving it which springs from people's connectedness to place and their felt responsibility for Heimat. Viewed from this perspective, Heimat is an interesting concept in the context of decision-making processes and regional management. %0 journal article %@ 1748-9326 %A Meier, H.E.M., Andersson, H.C., Arheimer, B., Blenckner, T., Chubarenko, B., Donnelly, C., Eilola, K., Gustafsson, B.G., Hansson, A., Havenhand, J., Höglund, A., Kuznetsov, I., MacKenzie, B.R., Müller-Karulis, B., Neumann, T., Niiranen, S., Piwowarczyk, J., Raudsepp, U., Reckermann, M., Ruoho-Airola, T., Savchuk, O.P., Schenk, F., Schimanke, S., Väli, G., Weslawski, J.-M., Zorita, E. %D 2012 %J Environmental Research Letters %P 034005 %R doi:10.1088/1748-9326/7/3/034005 %T Comparing reconstructed past variations and future projections of the Baltic Sea ecosystem—first results from multi-model ensemble simulations %U https://doi.org/10.1088/1748-9326/7/3/034005 %X Multi-model ensemble simulations for the marine biogeochemistry and food web of the Baltic Sea were performed for the period 1850–2098, and projected changes in the future climate were compared with the past climate environment. For the past period 1850–2006, atmospheric, hydrological and nutrient forcings were reconstructed, based on historical measurements. For the future period 1961–2098, scenario simulations were driven by regionalized global general circulation model (GCM) data and forced by various future greenhouse gas emission and air- and riverborne nutrient load scenarios (ranging from a pessimistic 'business-as-usual' to the most optimistic case). To estimate uncertainties, different models for the various parts of the Earth system were applied. Assuming the IPCC greenhouse gas emission scenarios A1B or A2, we found that water temperatures at the end of this century may be higher and salinities and oxygen concentrations may be lower than ever measured since 1850. There is also a tendency of increased eutrophication in the future, depending on the nutrient load scenario. Although cod biomass is mainly controlled by fishing mortality, climate change together with eutrophication may result in a biomass decline during the latter part of this century, even when combined with lower fishing pressure. Despite considerable shortcomings of state-of-the-art models, this study suggests that the future Baltic Sea ecosystem may unprecedentedly change compared to the past 150 yr. As stakeholders today pay only little attention to adaptation and mitigation strategies, more information is needed to raise public awareness of the possible impacts of climate change on marine ecosystems. %0 journal article %@ 1814-9324 %A Gomez-Navarro, J.J., Montavez, J.P., Jerez, S., Jimenez-Guerrero, P., Lorente-Plazas, R., Gonzalez-Rouco, J.F., Zorita, E. %D 2011 %J Climate of the Past %N 2 %P 451-472 %R doi:10.5194/cp-7-451-2011 %T A regional climate simulation over the Iberian Peninsula for the last millennium %U https://doi.org/10.5194/cp-7-451-2011 2 %X A high-resolution (30 km) regional paleoclimate simulation of the last millennium over the Iberian Peninsula (IP) is presented. The simulation was performed with a climate version of the mesoscale model MM5 driven by the global model ECHO-G. Both models were driven by the same reconstructions of several external forcing factors. The high spatial resolution of the regional model allows climatologists to realistically simulate many aspects of the climate in the IP, as compared to an observational data set in the reference period 1961–1990. Although the spatial-averaged values developed by the regional model are tightly driven by the boundary conditions, it is capable to develop a different realisation of the past climate at regional scales, especially in the high-frequency domain and for precipitation. This has to be considered when comparing the results of climate simulations versus proxy reconstructions. A preliminary comparison of the simulation results with reconstructions of temperature and precipitation over the IP shows good agreement in the warming trends in the last century of the simulation, although there are large disagreements in key periods such as the precipitation anomalies in the Maunder Minimum. %0 journal article %@ 1616-7341 %A Albrecht, F., Wahl, T., Jensen, J., Weisse, R. %D 2011 %J Ocean Dynamics %N 12 %P 2037-2050 %R doi:10.1007/s10236-011-0462-z %T Determining sea level change in the German Bight %U https://doi.org/10.1007/s10236-011-0462-z 12 %X periods. %0 journal article %@ 0171-8649 %A Kannen, A. %D 2011 %J Geographie und Schule %P 4-9 %T Kueste und Meer - Dynamische Natur-, Wirtschafts- und Kuestenraeume %U %X Zunehmende Nutzungsintensität und das Aufkommen neuer Nutzungen im Meer kennzeichnen die aktuelle Dynamik in Küsten- und Meeresräumen. Damit erhöht sich auch der Druck auf die Küsten- und Meeresökosysteme. Um den sich daraus ergebenden Konflikten zu begegnen werden neue, integrative Formen von Planung und Management eingeführt oder zumindest diskutiert. Gleichzeitig werden aber auch Wahrnehmungs- und Wertekonflikte in der Küstenbevölkerung sichtbar. %0 journal article %@ 0094-8276 %A Wahle, K., Stanev, E.V. %D 2011 %J Geophysical Research Letters %P L10603 %R doi:10.1029/2011GL047070 %T Consistency and complementarity of different coastal ocean observations: A neural network-based analysis for the German Bight %U https://doi.org/10.1029/2011GL047070 %X HF radar measurements in the German Bight and their consistency with other available observations were analyzed. First, an empirical orthogonal function (EOF) analysis of the radial component of the surface current measured by one radar was performed. Afterwards, Neural Networks (NNs) were trained to now- and forecast the first five EOFs from tide gauge measurements. The inverse problem, i.e., to forecast a sea level from these EOFs was also solved using NNs. For both problems, the influence of wind measurements on the nowcast/forecast accuracy was quantified. The forecast improves if HF radar data are used in combination with wind data. Analysis of the upscaling potential of HF radar measurements demonstrated that information from one radar station in the German Bight is representative of an area larger than the observational domain and could contribute to correcting information from biased observations or numerical models. %0 journal article %@ 0165-0009 %A Katsman, C.A., Sterl, A., Beersma, J.J., Van den Brink, H.W., Church, J.A., Hazeleger, W., Koop, R.E., Kroon, D., Kwadijk, J., Lammersen, R., Lowe, J., Oppenheimer, M., Plaag, H.P., Ridley, J., Storch, H.v., Vaughan, D,G., Vellinga, P., Vermeersen, L.L.A., Wal, R.S.W.van de, Weisse, R. %D 2011 %J Climatic Change %N 3-4 %P 617-645 %R doi:10.1007/s10584-011-0037-5 %T Exploring high-end scenarios for local sea level rise to develop flood protection strategies for a low-lying delta -The Netherlands as an example %U https://doi.org/10.1007/s10584-011-0037-5 3-4 %X Sea level rise, especially combined with possible 13 changes in storm surges 14 and increased river discharge resulting from climate change, poses a major threat in 15 low-lying river deltas. In this study we focus on a specific example of such a delta: the 16 Netherlands. We develop a plausible high-end scenario of 0.55 to 1.15 meters global 17 mean sea level rise, and 0.40 to 1.05 meters rise on the coast of the Netherlands by 18 2100 (excluding land subsidence), and more than three times these local values by 19 2200. Together with projected changes in storm surge height and peak river discharge, 20 these scenarios depict a complex, enhanced flood risk for the Dutch delta. %0 journal article %@ 0931-0983 %A Storch, H.v., Meinke, I., Stehr, N., Ratter, B., Krauss, W., Pielke, R.A.jr., Grundmann, R., Reckermann, M., Weisse, R. %D 2011 %J Zeitschrift fuer Umweltpolitik & Umweltrecht %N 1 %P 1-15 %T Regional Climate Services illustrated with experiences from Northern Europe %U 1 %X services. After a general discussion, experiences of providing these services on a regional and local scale – Northern Germany, the metropolitan area of Hamburg and the Baltic Sea Basin – during the last few years is reviewed.Key components of this regional climate service is the establishment of a regional climate office, of regional IPCC-like assessments of knowledge about regional and local climate change, and detailed homogeneous data sets describing changing weather statistics i.e., climate) in past decades and in perspectives for the next several decades. %0 journal article %@ 0894-8755 %A Teixeira, J., Cardoso, S., Bonazzola, M., Cole, J., DelGenio, A., DeMott, C., Franklin, C., Hannay, C., Jakob, C., Jiao, Y., Karlsson, J., Kitagawa, H., Koehler, M., Kuwano-Yoshida, A., LeDrian, C., Li, J., Lock, A., Miller, M.J., Marquet, P., Martins, J., Mechoso, C.R., Meijgaard, E.v., Meinke, I., Miranda, P.M.A., Mironov, D., Neggers, R., Pan, H.L., Randall, D.A., Rasch, P.J., Rockel, B., Rossow, W.B., Ritter, B., Siebesma, A.P., Soares, P.M.M., Turk, F.J., Vaillancourt, P.A., Engeln, A.v., Zhao, M. %D 2011 %J Journal of Climate %N 20 %P 5223-5256 %R doi:10.1175/2011JCLI3672.1 %T Tropical and Subtropical Cloud Transitions in Weather and Climate Prediction Models: The GCSS/WGNE Pacific Cross-Section Intercomparison (GPCI) %U https://doi.org/10.1175/2011JCLI3672.1 20 %X An alternative analysis of cloud cover mean statistics is proposed where sharp gradients in cloud cover along the GPCI transect are taken into account. This analysis shows that the negative cloud bias of some models and ERA40 in the stratocumulus regions (as compared to ISCCP) is associated not only with lower values of cloud cover in these regimes, but also with a stratocumulus-to-cumulus transition that occurs too early along the trade-wind Lagrangian trajectory. Histograms of cloud cover along the cross-section differ significantly between models. Some models exhibit a quasi-bimodal structure with cloud cover being either very large (close to 100%) or very small, while other models show a more continuous transition. The ISCCP observations suggest that reality is in-between these two extreme examples. These different patterns reflect the diverse nature of the cloud, boundary layer, and convection parameterizations in the participating weather and climate prediction models. %0 journal article %@ 0269-7491 %A Weinberg, I., Dreyer, A., Ebinghaus, R. %D 2011 %J Environmental Pollution %N 1 %P 125-132 %R doi:10.1016/j.envpol.2010.09.023 %T Waste water treatment plants as sources of polyfluorinated compounds, polybrominated diphenyl ethers and musk fragrances to ambient air %U https://doi.org/10.1016/j.envpol.2010.09.023 1 %X To investigate waste water treatment plants (WWTPs) as sources of polyfluorinated compounds (PFCs), polybrominated diphenyl ethers (PBDEs) and synthetic musk fragrances to the atmosphere, air samples were simultaneously taken at two WWTPs and two reference sites using high volume samplers. Contaminants were accumulated on glass fiber filters and PUF/XAD-2/PUF cartridges, extracted compound-dependent by MTBE/acetone, methanol, or hexane/acetone and detected by GC-MS or HPLC-MS/MS. Total (gas + particle phase) concentrations ranged from 97 to 1004 pg m−3 (neutral PFCs), 5 mg l− 1 in the storm periods. Waves lead to a higher frequency of resuspension and erosion events and increase mixing intensity in the water column during storm periods. During calm periods, SPM distribution is mainly shaped by currents. A different pattern, characterized by high SPM concentrations in off-shore areas, evolves instantly during transient storms events. %0 journal article %@ 1464-0325 %A Busch, J., Ahrens, L., Xie, Z., Sturm, R., Ebinghaus, R. %D 2010 %J Journal of Environmental Monitoring %P 1242-1246 %R doi:10.1039/c002242j %T Polyfluoroalkyl compounds in the East Greenland Arctic Ocean %U https://doi.org/10.1039/c002242j %X Polyfluoroalkyl compounds (PFCs) can be found ubiquitously in the marine environment. The transport of PFCs to remote locations is assumed to be by direct transport via oceanic water currents or indirectly via atmospheric transport of volatile precursor compounds. This study investigates the influence of ocean currents and atmospheric transport to the East Greenland Arctic Ocean (67.5–80.4° N). In this study, 38 water samples were collected in the Arctic summer in 2009 and analyzed by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS). Concentrations of three PFC classes could be quantified (i.e., perfluoroalkyl carboxylic acids (PFCAs), perfluoroalkyl sulfonates (PFSAs) and perfluoroalkyl sulfonamides) predominantly in a low pg L-1 range. Dominating compounds were PFOSA and PFOA with mean concentrations of 61 pg L-1 and 51 pg L-1, respectively. Statistically significant higher concentrations for PFOSA and PFHxA in the samples taken north of 75° N indicate an atmospheric influence on the concentrations found in the water samples. Significant differences in concentrations of PFHxS, PFHxA, PFHpA and PFOA for samples taken in coastal areas indicate an influence from the Greenlandic mainland. %0 journal article %@ 0025-326X %A Ahrens, L., Gerwinski, W., Theobald, N., Ebinghaus, R. %D 2010 %J Marine Pollution Bulletin %N 2 %P 255-260 %R doi:10.1016/j.marpolbul.2009.09.013 %T Sources of polyfluoroalkyl compounds in the North Sea, Baltic Sea and Norwegian Sea: Evidence from their spatial distribution in surface water %U https://doi.org/10.1016/j.marpolbul.2009.09.013 2 %X The spatial distribution of 15 polyfluoroalkyl compounds (PFCs) in surface water was investigated in the North Sea, Baltic Sea and Norwegian Sea. In addition, an interlaboratory comparison of the sampling techniques and analysis was conducted. Highest concentration in the North Sea was found near the coast, whereas the ∑PFC concentration decreased rapidly from 18.4 to 0.07 ng l−1 towards the open North Sea. The river Elbe could identify as a local input source for PFCs into the North Sea, whereas perfluorobutanoic acid (PFBA) was transported into the sampling area with the easterly current. In contrast to the North Sea, the distribution of PFCs in the Baltic Sea was relatively homogenous, where diffuse sources dominated. In general, the composition profile was influenced from local sources caused by human activities, whereas atmospheric depositions of here analysed PFCs were negligible, but it could have possibly an influence on low contaminated sites like the open North Sea or Norwegian Sea. %0 journal article %@ 0045-6535 %A Ahrens, L., Taniyasu, S., Yeung, L.W.Y., Yamashita, N., Lam, P.K.S., Ebinghaus, R. %D 2010 %J Chemosphere %N 3 %P 266-272 %R doi:10.1016/j.chemosphere.2010.01.045 %T Distribution of polyfluoroalkyl compounds in water, suspended particulate matter and sediment from Tokyo Bay, Japan %U https://doi.org/10.1016/j.chemosphere.2010.01.045 3 %X This study examined the environmental behaviour and fate of polyfluoroalkyl compounds (PFCs) found in water, suspended particulate matter (SPM) and sediment. The sampling of the sediment was performed at two stations from Tokyo Bay, Japan, in 2008. In addition, a depth profile of seawater was collected at three water layers from both sampling stations. The ∑PFC concentrations ranged from 16.7 to 42.3 ng L−1 in the water column, from 6.4 to 15.1 ng g−1 dry weight (dw) in the SPM fraction and from 0.29 to 0.36 dw in surface sediment. The distribution of PFCs was found to depend on their physicochemical characteristics. While short-chain perfluoroalkyl carboxylic acids (PFCAs) (C < 7) were exclusively detected in the dissolved phase, longer-chain PFCAs (C greater-or-equal, slanted 7), perfluoroalkyl sulfonates (PFSAs), ethylperfluorooctane sulfonamidoacetic acid (EtFOSAA), and perfluorooctane sulfonamide (PFOSA) appeared to bind more strongly to particles. Results showed that the sorption of PFCs on SPM increases by 0.52–0.75 log units for each additional CF2 moiety and that the sorption of PFSAs was 0.71–0.76 log units higher compared to the PFCA analogs. In addition, the sorption of PFCs was influenced by the organic carbon content. These data are essential for modelling the transport and environmental fate of PFCs. %0 journal article %@ 1463-5003 %A Schulz-Stellenfleth, J., Stanev, E.V. %D 2010 %J Ocean Modelling %N 3-4 %P 270-282 %R doi:10.1016/j.ocemod.2010.03.001 %T Statistical assessment of ocean observing networks – A study of water level measurements in the German Bight %U https://doi.org/10.1016/j.ocemod.2010.03.001 3-4 %X The proposed methods are applied to water level measurements in the German Bight. A numerical model is used to estimate the background statistics. Synthetic measurements provided by tide gauges, satellite altimeters, and HF radar are considered in the analysis. The estimation of the complete water level field in the German Bight is compared for altimeter and tide gauge measurements. It is shown that the orientation of the satellite track with respect to the coastline is of high relevance. The importance of water level measurements taken in deeper water, e.g., at the FINO-1 platform, is demonstrated. It is shown that continuous tide gauge measurements provide more information on the area mean water level in the German Bight than altimeter observations taken by ENVISAT and JASON-1/2. It is furthermore shown how the information provided by a tide gauge propagates with the Kelvin wave. Implications for the design of an assimilation scheme are discussed. %0 journal article %@ 0899-8418 %A Proemmel, K., Geyer, B., Jones, J.M., Widmann, M. %D 2010 %J International Journal of Climatology %N 5 %P 760-773 %R doi:10.1002/joc.1916 %T Evaluation of the skill and added value of a reanalysis-driven regional simulation for Alpine temperature %U https://doi.org/10.1002/joc.1916 5 %X Both the REMO simulation and the ERA40 reanalysis are validated against different station datasets of monthly and daily mean 2-m temperature. Correlation analysis shows that the temporal variability of temperature is well represented by both REMO and ERA40, whereas both show considerable biases. The REMO bias reaches 3 K in summer in regions known to experience a problem with summer drying in a number of regional models. The comparison of REMO and ERA40 shows that an added value of the former exists for all regions in winter. For the regions surrounding the Alps, the added value is absent in summer, whereas in the inner Alpine subregions with most complex orography, REMO performs better than ERA40 during the whole year. The only moderate value added by REMO in this hindcast set-up may be partly explicable by the fact that meteorological measurements are assimilated in the ERA40 reanalysis but not in the REMO simulation. %0 journal article %@ 0941-2948 %A Knote, C., Heinemann, G., Rockel, B. %D 2010 %J Meteorologische Zeitschrift %N 1 %P 11-23 %R doi:10.1127/0941-2948/2010/0424 %T Changes in weather extremes: Assessment of return values using high resolution climate simulations at convection-resolving scale %U https://doi.org/10.1127/0941-2948/2010/0424 1 %X Globale und regionale Klimamodelle werden derzeit mit räumlichen Auflösungen von 10 km oder mehr betrieben. State-of-the-art Wettervorhersagemodelle sind dagegen in ihrer Auflösung an der Kilometerskala angekommen, was die explizite Berechnung von Konvektion und die Berücksichtigung von topographischen Effekten z.B. in Mittelgebirgsregionen ermöglicht. Es besteht die Annahme, dass sich dadurch Extreme wie Starkwindereignisse, Gewitter oder Starkregen realistischer modellieren lassen. Das COSMO-CLM, die Klimaversion des Wettervorhersagemodells des COSMO-Konsortiums, wurde mit einer Auflösung von 1.3 km für das Gebiet von Rheinland-Pfalz betrieben. Zwei Zeitscheiben von jeweils 10 Jahren (1960-69 und 2015-25) zeigen die Veränderungen in Extremereignissen für das A1B Szenario des IPCC. Eine “Peaks over threshold” (POT) Extremwertanalyse gibt Aufschluss über Veränderungen in den Extrema des bodennahen Windes, der Temperatur und des Niederschlags. Die Stabilität der Analyse wird mit moving-block Bootstrapping getestet. Wird die Analyse auf die einzelnen Gitterpunkte angewendet, so zeigt sich, dass Bergregionen die größten Temperaturänderungen in den Extremen der Tagesminima zu erwarten haben, im Gegensatz zum Flachland, wo die Tagesmaxima der Temperatur die stärkste Veränderung zeigen. Änderungen in den Windgeschwindigkeiten bewegen sich um Null, im Mittel wie auch in den Extrema. Unsere Studie zeigt den Mehrwert, der durch erhöhte Variabilität meteorologischer Größen aufgrund besserer horizontaler Auflösung erreicht werden kann. %0 journal article %@ 1462-9011 %A Bray, D. %D 2010 %J Environmental Science & Policy %N 5 %P 340-350 %R doi:10.1016/j.envsci.2010.04.001 %T The scientific consensus of climate change revisited %U https://doi.org/10.1016/j.envsci.2010.04.001 5 %X This paper first reviews previous work undertaken to assess the level of scientific consensus concerning climate change, concluding that studies of scientific consensus concerning climate change have tended to measure different things. Three dimensions of consensus are determined: manifestation, attribution and legitimation. Consensus concerning these dimensions are explored in detail using a time series of data from surveys of climate scientists. In most cases, little difference is discerned between those who have participated in the IPCC process and those who have not. Consensus, however, in both groups does not amount to unanimity. Results also suggest rather than a single group proclaiming the IPCC does not represent consensus, there are now two groups, one claiming the IPCC makes overestimations (a group previously labeled skeptics, deniers, etc.) and a relatively new formation of a group (many of whom have participated in the IPCC process) proclaiming that IPCC tends to underestimate some climate related phenomena. %0 journal article %@ 0045-6535 %A Ahrens, L., Xie, Z., Ebinghaus, R. %D 2010 %J Chemosphere %N 8 %P 1011-1016 %R doi:10.1016/j.chemosphere.2009.11.038 %T Distribution of perfluoroalkyl compounds in seawater from Northern Europe, Atlantic Ocean, and Southern Ocean %U https://doi.org/10.1016/j.chemosphere.2009.11.038 8 %X The global distribution of perfluoroalkyl compounds (PFCs) were investigated in surface water samples collected onboard the Polarstern in Northern Europe, Atlantic and Southern Ocean (52°N–69°S) in 2008. The water samples were solid-phase extracted with Oasis WAX cartridges and analysed using the high-performance liquid chromatography interfaced to tandem mass spectrometry. Concentrations of various PFCs, including C4, C6, C8 perfluoroalkyl sulfonates (PFSAs), perfluorooctane sulfinate (PFOSi), C5–C12 perfluoroalkyl carboxylic acids (PFCA) and perfluorooctane sulfonamide (FOSA) were quantified. Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) were the predominant compounds with a maximum concentration of 232 and 223 pg L−1, respectively. Results indicate that industrial areas like the European Continent act as source of PFCs, while ocean water is an important as a sink as well as the transport medium of these compounds. Interestingly, in the equator area the ∑PFC concentration increased, which indicates that there exists an atmospheric or other unknown input source of PFCs. In the Southern Ocean only PFOS was detected which could be caused by atmospheric transport of its precursors. %0 journal article %@ 1616-7341 %A Grayek, S., Stanev, E.V., Kandilarov, R. %D 2010 %J Ocean Dynamics %N 1 %P 123-140 %R doi:10.1007/s10236-009-0249-7 %T On the response of Black Sea level to external forcing: altimeter data and numerical modelling %U https://doi.org/10.1007/s10236-009-0249-7 1 %X In this work, we address the Black Sea setup of Nucleus for European Modelling of the Ocean (NEMO), and in particular some model enhancements associated with the most important characteristic of ocean dynamics in this semi-enclosed basin, that is the sea-level variability and its relationship with water cycles and wind. Forcing data are presented in detail and compared with previously used coarser-resolution data. One emphasis in this paper is on the statistical analyses of forcing data and outputs from simulations with a focus on the sea level and its change. Numerical simulations are carried out as free run, and alternatively, altimeter data assimilation based on displacement of water properties in the pycnocline is used. Comparisons between the two runs identify the robustness of circulation driven by water balance and winter intensification. Problems in the model to replicate the redistribution of water properties between the two sub-basins in free-run mode are also discussed, which are observed during years with extreme climatic conditions. %0 journal article %@ 0196-2892 %A Winterfeldt, J., Andersson, A., Klepp, C., Bakan, S., Weisse, R. %D 2010 %J IEEE Transactions on Geoscience and Remote Sensing %N 1 %P 338-348 %R doi:10.1109/TGRS.2009.2023982 %T Comparison of HOAPS, QuikSCAT, and Buoy Wind Speed in the Eastern North Atlantic and the North Sea %U https://doi.org/10.1109/TGRS.2009.2023982 1 %X A systematic investigation and comparison of near-surface marine wind speed obtained from in situ and satellite observations, a reanalysis, and a reanalysis-driven regional climate model (RCM) are presented for the eastern North Atlantic and the North Sea. Wind-speed retrievals from QuikSCAT Level 2B 12.5 km and HOAPS-3-S are analyzed. The root-mean-square error (rmse) between QuikSCAT and buoy 10-m equivalent neutral wind (EQNW) is 1.50 (1.87) $hbox{m}! cdot! hbox{s}^{-1}$ using a colocation criteria of 0.1$^{circ}$ and 0.06$^{circ}$ (0.3$^{circ}$ and 0.2$^{circ}$) in longitudinal and latitudinal distances from buoy locations and within 10 (20) min, demonstrating that QuikSCAT's mission requirement of providing wind speed with an rmse of 2 $hbox{m}! cdot! hbox{s}^{-1}$ is met for the investigated area. The influence of three different stability and anemometer height correction algorithms for buoy wind speed on the buoy/QuikSCAT error is assessed: EQNW gives the best agreement with QuikSCAT data; however, differences are smaller than the buoy measurement error. The rmse between HOAPS and buoy wind converted to 10 m by the logarithmic wind profile is 2.27 (2.36) $hbox{m} cdot! hbox{s}^{-1}$ using a colocation of $0.1^{circ}! times! 0.06^{circ} (0.3^{circ}! times! 0.2^{circ})$ and within 10 (20) min. QuikSCAT shows good agreement with buoy wind for speeds up to 20 $hbox{m}! cdot! hbox{s}^{-1}$. HOAPS shows an underestimation of high wind speeds beyond 15–20 $hbox{m}! cdot! hbox{s}^{-1}$ probably due to a saturation of the return signal. The rmse between buoy wind speed and the National Centers of Environmental Prediction/Nati- onal Center for Atmospheric Research Reanalysis (NRA R1) and the spectrally nudged RCM REMO (SN-REMO) are 2.2 and 2.5 $hbox{m}! cdot! hbox{s}^{-1}$, respectively. %0 journal article %@ 0452-7739 %A Goennert, G., Jensen, J., Storch, H.v., Thumm, S., Wahl, T., Weisse, R. %D 2010 %J Die Kueste %P 225-256 %T Der Meeresspiegelanstieg. Ursachen, Tendenzen und Risikobewertung %U %X projiziert. Nach dem derzeitigen Kenntnisstand liegt der zentrale Wert dieser Projektionen für diese Region zwischen 40 und 80 cm bis zum Jahr 2100. %0 journal article %@ 1476-945X %A Gee, K., Burkhard, B. %D 2010 %J Ecological Complexity %N 3 %P 349-358 %R doi:10.1016/j.ecocom.2010.02.008 %T Cultural ecosystem services in the context of offshore wind farming: A case study from the west coast of Schleswig-Holstein %U https://doi.org/10.1016/j.ecocom.2010.02.008 3 %X Although frequently referred to in the literature, the concept of cultural ecosystem services (CES) has so far been limited in its application. Difficulties arise when specifying the nature of intangible values, but more significantly when it comes to relating intangible values to ecosystem functions. After setting out some conceptual issues, this paper uses a case study on the German North Sea coast to illustrate ways of operationalising the concept in a marine context. Based on a survey of local residents, we first identify current CES in the sea and the intangible values associated with them. Seascape and place emerge as useful conceptual bridges linking ecosystem functioning outcomes to key CES values. We then relate this to offshore wind farming, which some residents perceive as a significant threat to certain CES. Although the approach presented increases the visibility of intangible ecosystem values, the problem remains that such assessments are temporal, in need of added calibration and do not automatically put intangibles on a par with market ecosystem value. %0 journal article %@ 0941-2948 %A Rockel, B., Arritt, R., Rummukainen, M., Hense, A. %D 2010 %J Meteorologische Zeitschrift %N 3 %P 223-224 %R doi:10.1127/0941-2948/2010/0462 %T Editirial: The 2nd Lund Regional-scale Climate Modelling Workshop %U https://doi.org/10.1127/0941-2948/2010/0462 3 %X No abstract %0 journal article %@ 0143-1161 %A Li, X., Koenig, T., Schulz-Stellenfleth, J., Lehner, S. %D 2010 %J International Journal of Remote Sensing %N 17-18 %P 4969-4993 %R doi:10.1080/01431161.2010.485222 %T Validation and intercomparison of ocean wave spectra inversion schemes using ASAR wave mode data %U https://doi.org/10.1080/01431161.2010.485222 17-18 %X In addition to comparing conventional integral wave parameters normally used to assess the quality of inverted spectra, a comparison of individual PARSA spectra chosen in different sea state with the nearest numerical wave model spectra and the WVW spectra is performed to illustrate two-dimensional spectral differences. %0 journal article %@ 0938-9911 %A Schulz-Stellenfleth, J., Wahle, K., Staneva, J., Seemann, J., Cysewski, M.-C., Gurgel, K.-W., Schlick, T., Ziemer, F., Stanev, E. %D 2010 %J DGM-Mitteilungen (Deutsche Gesellschaft fuer Meeresforschung) %N 3 %P 3-8 %T Nutzung eines HF-Radarsystems zur Beobachtung und Vorhersage von Stroemungen in der Deutschen Bucht im Rahmen von COSYNA %U 3 %X No abstract %0 journal article %@ 0005-9099 %A Bruns, A., Gee, K. %D 2010 %J Berichte zur deutschen Landeskunde %N 1 %P 41-58 %T Der Kuesten- und Meeresraum zwischen traditionellen Kuestenbildern und neuen Steuerungsformen fuer eine nachhaltige Entwicklung %U 1 %X At present, the (re)discovery of the sea as an economic space exposes shortcomings with respect to the use of the marine environment. Offshore wind farming is a case in point that highlights shortcomings with respect to marine spatial planning. Economic interests need to be contrasted with the public perception of the coast and sea and visions for their future use. This paper places local views into the context of current forms and processes of spatial management at a national and regional level. This demonstrates clear discrepancies in multilevel governance. %0 journal article %@ 0028-0836 %A Zahn, M., Storch, H.v. %D 2010 %J Nature %P 309-312 %R doi:10.1038/nature09388 %T Decreased frequency of North Atlantic polar lows associated with future climate warming %U https://doi.org/10.1038/nature09388 %X Every winter, the high-latitude oceans are struck by severe storms that are considerably smaller than the weather-dominating synoptic depressions1. Accompanied by strong winds and heavy precipitation, these often explosively developing mesoscale cyclones—termed polar lows1—constitute a threat to offshore activities such as shipping or oil and gas exploitation. Yet owing to their small scale, polar lows are poorly represented in the observational and global reanalysis data2 often used for climatological investigations of atmospheric features and cannot be assessed in coarse-resolution global simulations of possible future climates. Here we show that in a future anthropogenically warmed climate, the frequency of polar lows is projected to decline. We used a series of regional climate model simulations to downscale a set of global climate change scenarios3 from the Intergovernmental Panel of Climate Change. In this process, we first simulated the formation of polar low systems in the North Atlantic and then counted the individual cases. A previous study4 using NCEP/NCAR re-analysis data5 revealed that polar low frequency from 1948 to 2005 did not systematically change. Now, in projections for the end of the twenty-first century, we found a significantly lower number of polar lows and a northward shift of their mean genesis region in response to elevated atmospheric greenhouse gas concentration. This change can be related to changes in the North Atlantic sea surface temperature and mid-troposphere temperature; the latter is found to rise faster than the former so that the resulting stability is increased, hindering the formation or intensification of polar lows. Our results provide a rare example of a climate change effect in which a type of extreme weather is likely to decrease, rather than increase. %0 journal article %@ 1726-4170 %A Holstein, J.M., Wirtz, K.W. %D 2010 %J Biogeosciences %N 11 %P 3741-3753 %R doi:10.5194/bg-7-3741-2010 %T Organic matter accumulation and degradation in subsurface coastal sediments: a model-based comparison of rapid sedimentation and aquifer transport %U https://doi.org/10.5194/bg-7-3741-2010 11 %X We found that both scenarios, advection and sedimentation, had solutions consistent with the observed pore water profiles. For this specific site, however, advective transport of particulate material had to be rejected since the reconstructed boundary conditions were rather improbable. In the alternative deposition set-up, model simulations suggested the deposition of the source OM about 60 yrs before cores were taken. A mean sedimentation rate of approximately 2 cm yr−1 indicates substantial changes in near coast tidal flat morphology, since sea level rise is at a much lower pace. High sedimentation rates most probably reflect the progradation of flats within the study area. These or similar morphodynamic features also occur in other coastal areas so that inverted redox succession by horizontal or vertical transport may be more common than previously thought. Consequently, regional values for OM remineralization rates may be higher than predicted from surface biogeochemistry. %0 journal article %@ 1448-2517 %A Sturm, R., Ahrens, L. %D 2010 %J Environmental Chemistry %N 6 %P 457-484 %R doi:10.1071/EN10072 %T Trends of polyfluoroalkyl compounds in marine biota and in humans %U https://doi.org/10.1071/EN10072 6 %X This review gives an overview of existing knowledge of polyfluoroalkyl compounds (PFCs) in humans and in marine biota. Temporal trends and spatial distribution of PFCs were globally compared in humans, marine mammals, seabirds and fish. In general, PFC concentrations in the environment have increased significantly from the beginning of the production up to the 1990s. After the phase-out of perfluorooctane sulfonyl fluoride (POSF) production starting in 2000, PFC concentrations in humans generally decreased. In marine biota no clear temporal trends were observed. The temporal trends depended on the species, their trophic levels and the geographical locations. PFC patterns in humans and in marine wildlife species were compared regarding perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), their shorter and longer chain homologues (C4–C15) and precursor compounds. Finally knowledge gaps were identified and recommendations for future work were presented. %0 journal article %@ 0177-8501 %A Meinke, I., Gerstner, E., Storch, H.v., Marx, A., Schipper, H., Kottmeier, C., Treffeisen, R., Lemke, P. %D 2010 %J Mitteilungen (Deutsche Meteorologische Gesellschaft) %N 2 %P 5-7 %T Regionaler Klimaatlas Deutschland der Helmholtz-Gemeinschaft informiert im Internet ueber moeglichen kuenftigen Klimawandel %U 2 %X richtet sich an die interessierte Öffentlichkeit sowie an Entscheidungsträger aus Politik und Wirtschaft. Alternativ steht zusätzlich eine Darstellung für Modellnutzer zur Verfügung. %0 journal article %@ 0165-0009 %A Tol, R.S.J., Wagner, S. %D 2010 %J Climatic Change %N 1-2 %P 65-79 %R doi:10.1007/s10584-009-9659-2 %T Climate change and violent conflict in Europe over the last millennium %U https://doi.org/10.1007/s10584-009-9659-2 1-2 %X We find that conflict was more intense during colder period, just like Zhang et al. (Clim Change 76:459–477, 2006) found for China. This relationship weakens in the industrialized era, and is not robust to the details of the climate reconstruction or to the sample period. As the correlation is negative and weakening, it appears that global warming would not lead to an increase in violent conflict in temperature climates. %0 journal article %@ %A Bray, D., Storch, H.v. %D 2010 %J Climate Science and Policy %P 18.08.2010 %T How do scientists assess the skill of climate models? %U %X In our surveys among climate scientists, we have asked – among others questions – also how well the components of climate models would perform. Three surveys were run in 1998, 2003 and 2008. They sampled mostly North Americans, Britons and Germans (CLISCI – for further details, such as sampling, return rates and related issues, refer to Bray, 2010a,b). A fourth survey was conducted in 2010 among climate scientists dealing with climate, climate change and impact in the Baltic Sea region with a majority of Scandinavian and Baltic participants (this was done in the framework of BALTEX; details, see Bray 2010c). In the following we will refer to CLISCI 1998, CLISCI 2003, CLISCI 2008 and BALTEX 2010. %0 journal article %@ 0013-936X %A Langer, V., Dreyer, A., Ebinghaus, R. %D 2010 %J Environmental Science and Technology %N 21 %P 8075-8081 %R doi:10.1021/es102384z %T Polyfluorinated Compounds in Residential and Nonresidential Indoor Air %U https://doi.org/10.1021/es102384z 21 %X Indoor air concentrations of fifteen volatile per- and polyfluorinated compounds (PFCs) (five fluorotelomer alcohols (FTOHs), three fluorotelomer acrylates (FTAs), three perfluorinated sulfonamido ethanols (FASEs), and three perfluorinated sulfonamides (FASAs)) were determined in residential and nonresidential indoor air environments. Air samples were taken with passive samplers, consisting of XAD-4 impregnated polyurethane foam (PUF) disks in steel housings. Impregnated PUF disks were extracted by fluidized bed extraction (FBE) using methyl-tert-butyl ether/acetone (1:1) and analyzed by gas chromatography−mass spectrometry. Total PFC indoor air concentrations ranged from 8.2 to 458 ng m−3. Individual PFC concentrations were between 42 pg m−3 (6:2 FTA) and 209 ng m−3 (8:2 FTOH). Concentrations of total FTOHs, FTAs, and FASAs + FASEs ranged from 0.2 to 152 ng m−3 (FTAs), from 3.3 to 307 ng m−3 (FTOHs), and from 4.4 to 148 ng m−3 (FASAs + FASEs). Most elevated individual, group, and total PFC concentrations were detected in two stores selling outdoor equipment, one furniture shop, and one carpet shop. Indoor air concentrations were several orders of magnitude higher than published outdoor air concentrations indicating indoor air environments as sources for PFCs to the atmosphere. Concentrations were used to estimate human exposure to investigated PFCs. %0 journal article %@ 0269-7491 %A Moeller, A., Ahrens, L., Sturm, R., Westerveld, J., Wielen, F.van der, Ebinghaus, R., de Voogt, P. %D 2010 %J Environmental Pollution %N 10 %P 3243-3250 %R doi:10.1016/j.envpol.2010.07.019 %T Distribution and sources of polyfluoroalkyl substances (PFAS) in the River Rhine watershed %U https://doi.org/10.1016/j.envpol.2010.07.019 10 %X The short-chained polyfluoroalkyl substances PFBA and PFBS replace PFOA and PFOA as dominating PFAS in surface waters in the River Rhine watershed. %0 journal article %@ 1017-0839 %A Staneva, J., Kourafalou, V., Tsiaras, K. %D 2010 %J Terrestrial, Atmospheric and Oceanic Sciences: TAO %N 1 %P 163-180 %R doi:10.3319/TAO.2009.06.08.03(IWNOP) %T Seasonal and Interannual Variability of the North-Western Black Sea Ecosystem %U https://doi.org/10.3319/TAO.2009.06.08.03(IWNOP) 1 %X This study describes the coupling between physical and biogeochemical models and analyses the response of the ecosystem in the north-western Black Sea to nutrient loads and climate changes. The basic physical and biological dynamics of the upper north-western Black Sea is illustrated as well. The physical model is based on the Princeton Ocean Model (POM); additionally, a parameterisation of mixed layer is included. The biogeochemical model is based on the European Regional Sea Ecosystem Model (ERSEM) and consists of five modules: (1) primary producers, (2) microbial loop, (3) mesozooplankton, (4) benthic nutrients, and (5) benthic biology. The ecosystem in ERSEM is subdivided into three functional types, producers (phytoplankton), decomposers (pelagic and benthic bacteria) and consumers (zooplankton and zoobenthos). Model-data comparisons have been performed for both calibrating and verifying coupled model simulations. We address here the impact of nutrient discharge from the Danube River on the functioning of the biological system. The evolution of the mixed layer, as well as the response of the biological system to variability of the nutrient discharge from the Danube River is described in detail. Several scenarios have been developed to study the impact which nutrient reduction has on the coastal marine system. The model predictions indicate that the biological system is very sensitive to the changes in nutrient concentrations, as well as to their ratios. %0 journal article %@ 1812-0784 %A Barth, A., Alvera-Azcarate, A., Gurgel, K.-W., Staneva, J., Port, A., Beckers, J.-M., Stanev, E.V. %D 2010 %J Ocean Science %N 1 %P 161-178 %R doi:10.5194/os-6-161-2010 %T Ensemble perturbation smoother for optimizing tidal boundary conditions by assimilation of High-Frequency radar surface currents – application to the German Bight %U https://doi.org/10.5194/os-6-161-2010 1 %X High-Frequency (HF) radars measure the ocean surface currents at various spatial and temporal scales. These include tidal currents, wind-driven circulation, density-driven circulation and Stokes drift. Sequential assimilation methods updating the model state have been proven successful to correct the density-driven currents by assimilation of observations such as sea surface height, sea surface temperature and in-situ profiles. However, the situation is different for tides in coastal models since these are not generated within the domain, but are rather propagated inside the domain through the boundary conditions. For improving the modeled tidal variability it is therefore not sufficient to update the model state via data assimilation without updating the boundary conditions. The optimization of boundary conditions to match observations inside the domain is traditionally achieved through variational assimilation methods. In this work we present an ensemble smoother to improve the tidal boundary values so that the model represents more closely the observed currents. To create an ensemble of dynamically realistic boundary conditions, a cost function is formulated which is directly related to the probability of each boundary condition perturbation. This cost function ensures that the boundary condition perturbations are spatially smooth and that the structure of the perturbations satisfies approximately the harmonic linearized shallow water equations. Based on those perturbations an ensemble simulation is carried out using the full three-dimensional General Estuarine Ocean Model (GETM). Optimized boundary values are obtained by assimilating all observations using the covariances of the ensemble simulation. %0 journal article %@ 1448-2517 %A Kirchgeorg, T., Weinberg, I., Dreyer, A., Ebinghaus, R. %D 2010 %J Environmental Chemistry %N 5 %P 429-434 %R doi:10.1071/EN10039 %T Perfluorinated compounds in marine surface waters: data from the Baltic Sea and methodological challenges for future studies %U https://doi.org/10.1071/EN10039 5 %X Poly- and perfluorinated compounds (PFCs) are chemicals of emerging environmental concern. Except for very few coastal sites, PFC contamination of the Baltic Sea has not been investigated. In order to assess the PFC contamination of Baltic Sea water and evaluate the spatial distribution of PFCs, 74 surface water samples from the entire Baltic Sea were taken during two sampling campaigns in the summer of 2008 and analysed for PFCs. Of 40 analysed PFCs, 13 were detected at concentrations below 1 ng L–1, which indicates a rather low PFC contamination of Baltic Sea surface water. Usually, PFOA was the analyte observed in highest concentrations followed by PFNA, PFBS, and PFOS. PFC concentrations decreased from the Kattegat to the Bothnian Bay and the Gulf of Finland, reflecting the decreasing population density and thus the potential contamination in corresponding catchments or the decreasing influence of potentially contaminated North Sea water. %0 journal article %@ 1448-2517 %A Dreyer, A., Shoeib, M., Fiedler, S., Barber, J., Harner, T., Schramm, K.-W., Jones, K., Ebinghaus, R. %D 2010 %J Environmental Chemistry %N 4 %P 350-358 %R doi:10.1071/EN10053 %T Field intercomparison on the determination of volatile and semivolatile polyfluorinated compounds in air %U https://doi.org/10.1071/EN10053 4 %X Fluorotelomer alcohols, perfluorinated sulfonamides or sulfonamido ethanols are volatile precursors of persistent perfluorinated acids. Published air-sampling strategies and analytical methods to determine these compounds differ. To assess performance on the determination of airborne polyfluorinated compounds, an intercomparison comprising four international research groups was established. Instrumental and analytical comparability between laboratories varied depending on the compound class. Variability in different sampling strategies was assessed for active (high-volume) v. passive samplers consisting of either semipermeable membrane devices or sorbent-impregnated polyurethane foam disks. Results from passive samplers were typically within an order of magnitude of air concentrations from averaged continuous high-volume samples. Smallest deviations (passive v. active) were observed for sorbent-impregnated polyurethane foam disk samplers with best agreement for fluorotelomer alcohols. This study reveals that it is important to be aware of several types of uncertainty or error for the determination of airborne polyfluorinated compounds and report data in this context or to take steps to minimise their impact. %0 journal article %@ 1561-8633 %A Gayer, G., Leschka, S., Noehren, I., Larsen, O., Guenther, H. %D 2010 %J Natural Hazards and Earth System Sciences %N 8 %P 1679-1687 %R doi:10.5194/nhess-10-1679-2010 %T Tsunami inundation modelling based on detailed roughness maps of densely populated areas %U https://doi.org/10.5194/nhess-10-1679-2010 8 %X Out of all simulations, the results of the worst case scenarios for each of the three priority areas are discussed. Earthquakes with magnitudes of MW=8.5 or higher lead to considerable inundation in all study sites. A spatially distinguished consideration of roughness has been found to be necessary for detailed modelling onshore. %0 journal article %@ 0264-8377 %A Gee, K. %D 2010 %J Land Use Policy %N 2 %P 185-194 %R doi:10.1016/j.landusepol.2009.05.003 %T Offshore wind power development as affected by seascape values on the German North Sea coast %U https://doi.org/10.1016/j.landusepol.2009.05.003 2 %X In Germany, the first permits have now been issued for the construction of large-scale offshore wind farms in the German Exclusive Economic Zone (EEZ). This paper focuses on perceptions of the local seascape and the role of aesthetic seascape qualities in shaping local attitudes to offshore wind farming. Based on a survey of local residents in the districts of Dithmarschen and North Frisia, it shows that aesthetic seascape perception alone cannot account for local attitudes to offshore wind farming. Three main aspects seem to come together to determine these attitudes: deeply held convictions of the sea as a natural space, deeply held views of the local landscape and linked to this local identity, and also perceptions of renewable energies in combination with attitudes to issues such as climate change and sea level rise. The paper draws some conclusions on the future of the sea as a natural space or energy space.