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Globally, impacts of climate change display an increasingly negative development of marine biomass, but there is large regional variability. In this analysis of future climate change on stock productivity proxies for the North Sea, the Norwegian Sea, and the Barents Sea, we have provided calculations of accumulated directional effects as a function of climate exposure and sensitivity attributes. Based on modelled changes in physical and biogeochemical variables from three scenarios and knowledge of 13 different stocks' habitats and response to climate variations, climate exposures have been weighted, and corresponding directions these have on the stocks have been decided. SSP1‐2.6 gives mostly a weak cooling in all regions with almost negligible impacts on all stocks. SSP2‐4.5 and SSP5‐8.5 both provide warmer conditions in the long term but are significantly different in the last 30 years of the century when the SSP5‐8.5 warming is much stronger. The results show that it is the current stocks of cod and Calanus finmarchicusin the North Sea, and polar cod and capelin in the Barents Sea that will be most negatively affected by strong warming. Stocks that can migrate north into the northern seas such as hake in the Norwegian Sea, or stocks that are near the middle of the preferred temperature range such as mackerel and herring in the Norwegian Sea and cod and Calanus finmarchicus in the Barents Sea, are the winners in a warmer climate. The highly different impacts between the three scenarios show that multiple scenario studies of this kind matter. [ABSTRACT FROM AUTHOR]

The North Sea and the Baltic Sea still experience eutrophication and deoxygenation despite large international efforts to mitigate such environmental problems. Due to the highly different oceanographic frameworks of the two seas, existing modelling efforts have mainly focused on only one of the respective seas, making it difficult to study interbasin exchange of mass and energy. Here, we present NEMO–SCOBI, an ocean model (NEMO-Nordic) coupled to the Swedish Coastal and Ocean Biogeochemical model (SCOBI), that covers the North Sea, the Skagerrak–Kattegat transition zone and the Baltic Sea. We address its validity to further investigate biogeochemical changes in the North Sea–Baltic Sea system. The model reproduces the long-term temporal trends, the temporal variability, the yearly averages and the general spatial distribution of all of the assessed biogeochemical parameters. It is particularly suitable for use in future multi-stressor studies, such as the evaluation of combined climate and nutrient forcing scenarios. In particular, the model performance is best for oxygen and phosphate concentrations. However, there are important differences between model results and observations with respect to chlorophyll a and nitrate in coastal areas of the southeastern North Sea, the Skagerrak–Kattegat transition zone, the Gulf of Riga, the Gulf of Finland and the Gulf of Bothnia. These are partially linked to different local processes and biogeochemical forcing that lead to a general overestimation of nitrate. Our model results are validated for individual areas that are in agreement with policy management assessment areas, thereby providing added value with respect to better contributing to international programmes aiming to reduce eutrophication in the North Sea–Baltic Sea system. [ABSTRACT FROM AUTHOR]

Downscaling physical forcing from global climate models is both time consuming and labor demanding and can delay or limit the physical forcing available for regional marine ecosystem modelers. Earlier studies have shown that downscaled physics is necessary for capturing the dynamics of primary production and lower trophic levels; however, it is not clear how higher trophic levels respond to the coarse resolution physics of global models. Here, we apply the Nordic and Barents Seas Atlantis ecosystem model (NoBa) to study the consequences of using physical forcing from global climate models versus using that from regional models. The study is therefore (i) a comparison between a regional model and its driving global model to investigate the extent to which a global climate model can be used for regional ecosystem predictions and (ii) a study of the impact of future climate change in the Nordic and Barents Seas. We found that few higher trophic level species were affected by using forcing from a global versus a regional model, and there was a general agreement in future biomass trends and distribution patterns. However, the slight difference in temperature between the models dramatically impacted Northeast Arctic cod (Gadus morhua), which highlights how species projection uncertainty could arise from poor physical representation of the physical forcing, in addition to uncertainty in the ecosystem model parameterization. [ABSTRACT FROM AUTHOR]

Sea-ice models fill many purposes; they are used in global climate models or for short-term forecasts to plan shipping routes. No matter what their output is used for, understanding the cause for their variability is crucial. In the this study two commonly used sea-ice models, CICE and SI3 were compared after running both models with similar boundary condition, on the same grid, with the same forcing and initialised with the same data, with the aim to understand how the two models differ from each other when forced equally. The set-up also allows linking certain model biases observed in both models to the external forcing. We found that the models compare well to sea ice concentration, sea ice thickness and snow thickness observations, with small regional differences, which could be linked to different model processes. The processes with the highest influence are the drag formulation, the albedo, and the treatment of snow. We find that the treatment of snow has a significant influence on the difference in sea ice thickness between the models, even though their forcing is equal. [ABSTRACT FROM AUTHOR]

Climate change is especially strong in the region of the Arctic Ocean, and will have an important impact on its thermo‐haline structure. We analyze the results of a hindcast simulation of a new 3D ocean model of the Arctic and North Atlantic oceans for the period 1970–2019. We compared the time period 1970–1999 with the time period 2010–2019. The comparison showed that there is a decrease of stratification between the two periods over most of the shallow Arctic shelf seas and in the core of the Transpolar Ice Drift. Fresh water inputs to the ocean surface decline, and inputs of momentum to the ocean increase, which can explain the decrease in stratification. The comparison also showed that the mixed layer becomes deeper during winter, in response to the weakened stratification owing to increased vertical mixing. The comparison of summer mixed layer depths between the two time periods follows a deepening pattern that is less evident. Regional exceptions include the Nansen Basin and the part of the Canadian Basin bordering the Canadian Archipelago, where the mixed layer shoals. Trends of freshwater fluxes imply that the changes of haline stratification in these regions are also influenced by other processes, for example, horizontal advection of fresh water, increased mixing and changes in the underlaying water masses. Runoff increase toward the Arctic Ocean can locally decrease but also increase salinity, and has an impact on stratification which can be explained by coastal dynamics. The results emphasize the non‐linear nature of Arctic Ocean dynamics. Plain Language Summary: We analyzed the results of an ocean model simulation for the Arctic and North Atlantic oceans for the period 1970–2019. Our model is in line with the recent observed changes in the Arctic Ocean and allows, in contrast to the rather sparse observations, a detailed assessment of stratification changes. These changes will affect the Arctic ecosystem and are also believed to affect the large scale ocean circulation. We show that major changes in upper ocean conditions are caused by changes in the fresh water supply by sea ice and varying effect of the wind on regions that are now becoming ice‐free. We also study the effect of changes in river runoff into the Arctic Ocean. Our study shows that an increase in river runoff can change the coastal circulation and results, paradoxically, in regions of higher salinity. These results point to the importance of modeling tools when it comes to a better understanding of ocean processes in a changing climate. Key Points: Results from a hindcast simulation of the Arctic Ocean for the period 1970–2019 show strong changes in stratificationThe changes in stratification are explained by altered surface stress and freshwater fluxesTrends in river runoff have little effect on the mixed layer depth but change the Arctic coastal circulation [ABSTRACT FROM AUTHOR]

Deep-sea marine fishes support important fisheries but estimates of their distributions are often incomplete as the data behind them may reflect fishing practices, access rights, or political boundaries, rather than actual geographic distributions. We use a simple suitable habitat model based on bottom depth, temperature, and salinity to estimate the potential distribution of Greenland halibut (Reinhardtius hippoglossoides). A large presence-only dataset is examined using multivariate kernel densities to define environmental envelopes, which we link to spatial distribution using a pan-Arctic oceanographic model. Occurrences generally fit the model well, although there were gaps in the predicted circum-Arctic distribution likely due to limited survey activity in many of the ice-covered seas around the Arctic Ocean. Bottom temperature and depth were major factors defining model fit to observations, but other factors, such as ecosystem interactions and larval drift could also influence distribution. Model predictions can be tested by increasing sampling effort in poorly explored regions and by studying the connectivity of putative populations. While abundances of Greenland halibut in the High Arctic are currently low, some areas are predicted to be suitable habitat for this species, suggesting that on-going sea-ice melt may lead to fisheries expansion into new areas. [ABSTRACT FROM AUTHOR]

The Bosphorus exchange is of critical importance for hydrodynamics and hydroclimatology of the Black Sea. In this study, we report on the development of a medium-resolution circulation model of the Black Sea, making use of surface atmospheric forcing with high space and time resolution, climatic river fluxes and strait exchange, enabled by adding elementary details of strait and coastal topography and seasonal hydrology specified in an artificial box on the Marmara Sea side. Particular attention is given to circulation, mixing and convective water mass formation processes in the model, which are then compared with observations. Open boundary conditions relaxed to seasonal hydrology specified in the artificial box are found to enable Bosphorus exchange with a proper upper layer, lower layer and net fluxes comparable to the observed ranges. These improvements at the artificial boundary and in the interior evolution of the Black Sea allow the study to capture daily, seasonal to decadal climatic variability and change observed in the Black Sea in the last few decades. [ABSTRACT FROM AUTHOR]

We studied circulation patterns in the Gulf of Finland (GoF), an estuary-like sub-basin of the Baltic Sea. Circulation patterns in the GoF are complex and vary from season to season and year to year. Estuarine circulation in the gulf is heavily modified by many factors, such as wind forcing, topography and geostrophic effects. Based on a 7-year run of the NEMO 3D hydrodynamic model with a 500 m horizontal resolution, we analysed seasonal changes of mean circulation patterns. We found that there were clear seasonal differences in the circulation patterns in the GoF. Features that moved or changed direction from season to season were damped or hidden in the averages. To further study these differences, we also carried out a self-organising map (SOM) analysis of currents for several latitudinal sections. The results of the SOM analysis emphasised the estuary-like nature of the GoF. Circulation changed rapidly from normal estuarine circulation to reverse estuarine circulation. The dominant southwesterly winds supported the reversal of the estuarine circulation. Both normal and reversed estuarine circulation were roughly as common in our data. The SOM analysis also demonstrated how the long-term cyclonic mean circulation field and the average salinity field emerged from the interaction of normal and reversed estuarine circulation. [ABSTRACT FROM AUTHOR]

The Bosphorus exchange is of critical importance for hydrodynamics of the Black Sea. In this study, we report on the development of a medium resolution circulation model of the Black Sea, making use of up-to-date topography, atmospheric forcing with high space and time resolution, climatic river fluxes and strait exchange enabled by adding the Bosphorus Strait with an artificial box on the Marmara Sea side. Particular attention is given to circulation, mixing, convective water mass formation processes compared with observations. The present formulation with temperature and salinity relaxed to the observed seasonal climatology of the Marmara box and open boundary conditions are found to enable Bosphorus exchange with upper, lower layer and net fluxes comparable to the observed range. This in turn enables to capture the trend of rapid climatic change observed in the Black Sea in the last decade. [ABSTRACT FROM AUTHOR]

In this study, the numerical dynamic-thermodynamic LIM 3.6 sea-ice model of NEMO-Nordic 1.0 was validated and a model evaluation method is described. The modelled ice concentration was compared with the remotely sensed sea-ice concentration data of 2009-2011. The spatiotemporal distribution of the sea-ice concentration over the Baltic Sea was analyzed. The model ice output values were compared with the observation data to evaluate the model ice product performance. The observed ice concentration values were subtracted from the respective model output values in the grid cells and stripes of sea area. Moreover, the calculated and actual ice extent values were compared. The model output was generally compatible (difference of < 25%) with the observations. The calculated extent of the sea-ice cover corresponded well with the observed extent. The correlation coefficients were 0.95 and 0.96 for the winters of 2009/2010 and 2010/2011, respectively. [ABSTRACT FROM AUTHOR]

Coastal seas receive large amounts of terrestrially derived organic carbon (OC). The fate of this carbon, and its impact on the marine environment, is however poorly understood. Here we combine underway CO2 partial pressure (pCO2) measurements with coupled 3-D hydrodynamical–biogeochemical modelling to investigate whether remineralization of terrestrial dissolved organic carbon (tDOC) can explain CO2 supersaturated surface waters in the Gulf of Bothnia, a subarctic estuary. We find that a substantial remineralization of tDOC and a strong tDOC-induced light attenuation dampening the primary production are required to reproduce the observed CO2 supersaturated waters in the nearshore areas. A removal rate of tDOC of the order of 1 year, estimated in a previous modelling study in the same area, gives a good agreement between modelled and observed pCO2. The remineralization rate is on the same order as bacterial degradation rates calculated from published incubation experiments, suggesting that bacteria has the potential to cause this degradation. Furthermore, the observed high pCO2 values during the ice-covered season argue against photochemical degradation as the main removal mechanism. All of the remineralized tDOC is outgassed to the atmosphere in the model, turning the northernmost part of the Gulf of Bothnia into a source of CO2 to the atmosphere. [ABSTRACT FROM AUTHOR]

We present Nemo-Nordic, a Baltic and North Sea model based on the NEMO ocean engine. Surrounded by highly industrialized countries, the Baltic and North seas and their assets associated with shipping, fishing and tourism are vulnerable to anthropogenic pressure and climate change. Ocean models providing reliable forecasts and enabling climatic studies are important tools for the shipping infrastructure and to get a better understanding of the effects of climate change on the marine ecosystems. Nemo-Nordic is intended to be a tool for both short-term and long-term simulations and to be used for ocean forecasting as well as process and climatic studies. Here, the scientific and technical choices within Nemo-Nordic are introduced, and the reasons behind the design of the model and its domain and the inclusion of the two seas are explained. The model's ability to represent barotropic and baroclinic dynamics, as well as the vertical structure of the water column, is presented. Biases are shown and discussed. The short-term capabilities of the model are presented, especially its capabilities to represent sea level on an hourly timescale with a high degree of accuracy. We also show that the model can represent longer timescales, with a focus on the major Baltic inflows and the variability in deep-water salinity in the Baltic Sea. [ABSTRACT FROM AUTHOR]

Coastal seas receive large amounts of terrestrially derived organic carbon (OC). The fate of this carbon, and its impact on the marine environment, is however poorly understood. Here we combine underway CO2 partial pressure (pCO2) measurements with coupled 3D hydrodynamical-biogeochemical modelling to investigate whether remineralization of terrestrial dissolved organic carbon (tDOC) can explain CO2 supersaturated surface waters in the Gulf of Bothnia, a subarctic estuary. We find that a substantial remineralization of tDOC, and that a strong tDOC induced light attenuation dampening the primary production, is required to reproduce the observed CO2 supersaturated waters in the nearshore areas. A removal rate of tDOC of the order of one year, estimated in a previous modelling study in the same area, gives a good agreement between modelled and observed pCO2. The remineralization rate is on the same order as bacterial degradation rates calculated from published incubation experiments, suggesting that this remineralization could be caused by bacterial degradation. Furthermore, the observed high pCO2 values during the ice covered season argues against photochemical degradation as the main removal mechanism. All of the remineralized tDOC is outgassed to the atmosphere in the model, turning the northernmost part of the Gulf of Bothnia to a source of atmospheric CO2. [ABSTRACT FROM AUTHOR]

We present Nemo-Nordic, a Baltic & North Sea model based on the NEMO ocean engine. Surrounded by highly industrialised countries, the Baltic and North seas, and their assets associated with shipping, fishing and tourism; are vulnerable to anthropogenic pressure and climate change. Ocean models providing reliable forecasts, and enabling climatic studies, are important tools for the shipping infrastructure and to get a better understanding of effects of climate change on the marine ecosystems. Nemo-Nordic is intended to come as a tool for both short term and long term simulations, and to be used for ocean forecasting as well as process and climatic studies. Here, the scientific and technical choices within Nemo-Nordic are introduced, and the reasons behind the design of the model and its domain, and the inclusions of the two seas, are explained. The model's ability to represent barotropic and baroclinic dynamics, as well as the vertical structure of the water column, is presented. Biases are shown and discussed. The short term capabilities of the model are presented, and especially its capabilities to represent sea level on an hourly timescale with a high degree of accuracy. We also show that the model can represent longer time scale, with a focus on the Major Baltic Inflows and the variability of deep water salinity in the Baltic Sea. [ABSTRACT FROM AUTHOR]

An ocean model covering the Baltic Sea area is forced by several climate scenarios for a period extending from 1961 to 2100. The Baltic Sea overturning circulation is then analyzed. The analysis shows that this circulation decreases between the end of the 20th century and the end of the 21st century, and that the decrease is amplified in the case of the strongest greenhouse gas emission scenarios, which corresponds with the highest warming cases. The reasons behind this decrease in overturning circulation are investigated. A strong increase of thermal stratification is noticed at the level of the Baltic Sea mixed layer. Based on buoyancy flux considerations, we demonstrate that the decrease in overturning circulation coincides with the increase of thermal stratification. Evidence shows that the underlying process is linked to a smaller erosion of the halocline due to a higher shielding, itself linked with a stronger and longer seasonal thermocline. This theory works if surface wind mixing is not taken into account directly in the computation of buoyancy fluxes. [ABSTRACT FROM AUTHOR]

Many coastal seas worldwide are affected by human impacts such as eutrophication, causing, inter alia, oxygen depletion and extensive areas of hypoxia. Depending on the region, global warming may reinforce these environmental changes by reducing air-sea oxygen fluxes, intensifying internal nutrient cycling and increasing river-borne nutrient loads. The development of appropriate management plans to more effectively protect the marine environment requires projections of future marine ecosystem states. However, projections with regional climate models commonly suffer from shortcomings in the driving global General Circulation Models (GCMs). The differing sensitivities of GCMs to increased greenhouse gas emissions impact regional projections considerably. In this study, we focused on one of the most threatened coastal seas, the Baltic Sea, and estimated uncertainties in projections due to GCM deficiencies relative to uncertainties caused by future greenhouse gas emissions and nutrient load scenarios. To address the latter, transient simulations of the period 1975-2098 were performed using the initial conditions from an earlier reconstruction with the same Baltic Sea model (starting in 1850). To estimate the impacts of GCM deficiencies, dynamical downscaling experiments with four driving global models were carried out for two greenhouse gas emission scenarios, RCP4.5 and 8.5, and for three nutrient load scenarios covering the plausible range between low and high loads. The results of primary production, nitrogen fixation, and hypoxic areas show that uncertainties caused by the various nutrient load scenarios are greater than the uncertainties due to global model deficiencies and future greenhouse gas emissions. In all scenario simulations, a proposed nutrient load abatement strategy, i.e., the Baltic Sea Action Plan, will lead to a significant improvement in the overall environmental state. However, the projections cannot provide detailed information on the timing and the reductions of future hypoxic areas due to uncertainties in salinity projections caused by uncertainties in projections of the regional water cycle and of the global mean sea level rise. [ABSTRACT FROM AUTHOR]

Abstract: High inputs of nutrients and organic matter make coastal seas places of intense air‐sea CO2 exchange. Due to their complexity, the role of coastal seas in the global air‐sea CO2 exchange is, however, still uncertain. Here, we investigate the role of phytoplankton stoichiometric flexibility and extracellular DOC production for the seasonal nutrient and CO2 partial pressure (pCO2) dynamics in the Gulf of Bothnia, Northern Baltic Sea. A 3‐D ocean biogeochemical‐physical model with variable phytoplankton stoichiometry is for the first time implemented in the area and validated against observations. By simulating non‐Redfieldian internal phytoplankton stoichiometry, and a relatively large production of extracellular dissolved organic carbon (DOC), the model adequately reproduces observed seasonal cycles in macronutrients and pCO2. The uptake of atmospheric CO2 is underestimated by 50% if instead using the Redfield ratio to determine the carbon assimilation, as in other Baltic Sea models currently in use. The model further suggests, based on the observed drawdown of pCO2, that observational estimates of organic carbon production in the Gulf of Bothnia, derived with the 14 C method, may be heavily underestimated. We conclude that stoichiometric variability and uncoupling of carbon and nutrient assimilation have to be considered in order to better understand the carbon cycle in coastal seas. [ABSTRACT FROM AUTHOR]

The Baltic Sea is a seasonally ice-covered marginal sea in northern Europe with intense wintertime ship traffic and a sensitive ecosystem. Understanding and modeling the evolution of the sea-ice pack is important for climate effect studies and forecasting purposes. Here we present and evaluate the sea-ice component of a new NEMO-LIM3.6-based ocean-sea-ice setup for the North Sea and Baltic Sea region (NEMO-Nordic). The setup includes a new depth-based fast-ice parametrization for the Baltic Sea. The evaluation focuses on long-term statistics, from a 45-year long hindcast, although short-term daily performance is also briefly evaluated. We show that NEMO-Nordic is well suited for simulating the mean sea-ice extent, concentration, and thickness as compared to the best available observational data set. The variability of the annual maximum Baltic Sea ice extent is well in line with the observations, but the 1961- 2006 trend is underestimated. Capturing the correct ice thickness distribution is more challenging. Based on the simulated ice thickness distribution we estimate the undeformed and deformed ice thickness and concentration in the Baltic Sea, which compares reasonably well with observations. [ABSTRACT FROM AUTHOR]

The fate of terrestrial organic matter brought to the coastal seas by rivers and its role in the global carbon cycle are still not very well known. Here the degradation rate of terrestrial dissolved organic carbon (DOCter) is studied in the Baltic Sea, a subarctic semienclosed sea, by releasing it as a tracer in a 3-D circulation model and applying linear decay constants. A good agreement with available observational data is obtained by parameterizing the degradation in two rather different ways: one by applying a decay time on the order of 10 years to the whole pool of DOCter and one by dividing the DOCter into one refractory pool and one pool subject to a decay time on the order of 1 year. The choice of parameterization has a significant effect on where in the Baltic Sea the removal takes place, which can be of importance when modeling the full carbon cycle and the CO2 exchange with the atmosphere. In both cases the biogeochemical decay operates on time scales less than the water residence time. Therefore, only a minor fraction of the DOCter reaches the North Sea, whereas approximately 80% is removed by internal sinks within the Baltic Sea. This further implies that DOCter mineralization is an important link in land-sea-atmosphere cycling of carbon in coastal and shelf seas that are heavily influenced by riverine DOC. [ABSTRACT FROM AUTHOR]

A new regional coupled model system for the North Sea and the Baltic Sea is developed, which is composed of the regional setup of ocean model NEMO, the Rossby Centre regional climate model RCA4, the sea ice model LIM3 and the river routing model CaMa-Flood. The performance of this coupled model system is assessed using a simulation forced with ERA-Interim reanalysis data at the lateral boundaries during the period 1979–2010. Compared to observations, this coupled model system can realistically simulate the present climate. Since the active coupling area covers the North Sea and Baltic Sea only, the impact of the ocean on the atmosphere over Europe is small. However, we found some local, statistically significant impacts on surface parameters like 2 m air temperature and sea surface temperature (SST). A precipitation-SST correlation analysis indicates that both coupled and uncoupled models can reproduce the air–sea relationship reasonably well. However, the coupled simulation gives slightly better correlations even when all seasons are taken into account. The seasonal correlation analysis shows that the air–sea interaction has a strong seasonal dependence. Strongest discrepancies between the coupled and the uncoupled simulations occur during summer. Due to lack of air–sea interaction, in the Baltic Sea in the uncoupled atmosphere-standalone run the correlation between precipitation and SST is too small compared to observations, whereas the coupled run is more realistic. Further, the correlation analysis between heat flux components and SST tendency suggests that the coupled model has a stronger correlation. Our analyses show that this coupled model system is stable and suitable for different climate change studies. [ABSTRACT FROM AUTHOR]

An ensemble of regional climate change scenarios for the North Sea is validated and analyzed. Five Coupled Model Intercomparison Project Phase 5 (CMIP5) General Circulation Models (GCMs) using three different Representative Concentration Pathways (RCPs) have been downscaled with the coupled atmosphere–ice–ocean model RCA4-NEMO. Validation of sea surface temperature (SST) against different datasets suggests that the model results are well within the spread of observational datasets. The ensemble mean SST with a bias of less than 1 ∘ C is the solution that fits the observations best and underlines the importance of ensemble modeling. The exchange of momentum, heat, and freshwater between atmosphere and ocean in the regional, coupled model compares well with available datasets. The climatological seasonal cycles of these fluxes are within the 95% confidence limits of the datasets. Towards the end of the 21st century the projected North Sea SST increases by 1.5 ∘ C (RCP 2.6), 2 ∘ C (RCP 4.5), and 4 ∘ C (RCP 8.5), respectively. Under this change the North Sea develops a specific pattern of the climate change signal for the air–sea temperature difference and latent heat flux in the RCP 4.5 and 8.5 scenarios. In the RCP 8.5 scenario the amplitude of the spatial heat flux anomaly increases to 5 W/m 2 at the end of the century. Different hypotheses are discussed that could contribute to the spatially non-uniform change in air–sea interaction. The most likely cause for an increased latent heat loss in the central western North Sea is a drier atmosphere towards the end of the century. Drier air in the lee of the British Isles affects the balance of the surface heat budget of the North Sea. This effect is an example of how regional characteristics modulate global climate change. For climate change projections on regional scales it is important to resolve processes and feedbacks at regional scales. [ABSTRACT FROM AUTHOR]

The Etesian wind regime dominating the climate of the Aegean Sea in summer often influences a larger area extending from the Balkans and the Black Sea to the Levantine Basin of the Eastern Mediterranean. The steady dry northerly winds descending from the Balkans in summer often incite forest fires in the Aegean Sea region, while the moist air picked up from the sea and trapped against the mountainous eastern Black Sea coast results in severe floods. The intense upwelling on the southern Black Sea and the eastern Aegean Sea result from steady winds aligned with the coast. Case studies based on recent observations and model simulations illustrate these events. [ABSTRACT FROM AUTHOR]