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We analyze the climate change signal in the Mediterranean Sea using the regionally coupled model REMO–OASIS–MPIOM (ROM; abbreviated from the regional atmosphere model, the OASIS3 coupler and the Max Planck Institute Ocean Model). The ROM oceanic component is global with regionally high horizontal resolution in the Mediterranean Sea so that the water exchanges with the adjacent North Atlantic and Black Sea are explicitly simulated. Simulations forced by ERA-Interim show an accurate representation of the present Mediterranean climate. Our analysis of the RCP8.5 (representative concentration pathway) scenario using the Max Planck Institute Earth System Model shows that the Mediterranean waters will be warmer and saltier throughout most of the basin by the end of this century. In the upper ocean layer, temperature is projected to have a mean increase of 2.7 ∘C, while the mean salinity will increase by 0.2 psu, presenting a decreasing trend in the western Mediterranean in contrast to the rest of the basin. The warming initially takes place at the surface and propagates gradually to deeper layers. Hydrographic changes have an impact on intermediate water characteristics, potentially affecting the Mediterranean thermohaline circulation in the future.

Metocean modeling resources from an operational oceanography system are applied to assess the hazard of bacterial contamination, resulting from domestic/industrial wastewater discharged into potential bivalve mollusk harvesting areas in Cadiz Bay (Andalusia). The proposed methodology is aimed to at meeting the European Union regulations and best practices for the management and monitoring of this harvesting activity. Modeled current fields, corresponding to scenarios with different wind and tidal conditions, are incorporated in a Lagrangian particle-tracking model, specifically designed to simulate the fate of the bacterial content of wastewaters discharged into the Bay. Numerical results are used to obtain various indices of occurrence and hazard maps of fecal contamination in seawater. The proposed indices also allow estimating fecal contamination fields if appropriate information of discharges and bacterial loads of the wastewater sources are available. Qualitative validation of results shows considerable agreement with measured contamination patterns. The areas with highest exposure to bacterial contamination are the Sancti Petri Channel and the central region of the Inner Bay, although a substantial variability depending on wind conditions is found. Unauthorized occasional wastewater discharges have a considerable impact on local water quality, while regulated wastewater sources are responsible for the larger-scale bacterial contamination pattern. The methodology developed is exportable to other environments and coastal management activities.

The Canary current upwelling is one of the major eastern boundary coastal upwelling systems in the world, bearing a high productive ecosystem and commercially important fisheries. The Canary current upwelling system (CCUS) has a large latitudinal extension, usually divided into upwelling zones with different characteristics. Eddies, filaments and other mesoscale processes are known to have an impact in the upwelling productivity, thus for a proper representation of the CCUS and high horizontal resolution are required. Here we assess the CCUS present climate in the atmosphere-ocean regionally coupled model. The regional coupled model presents a global oceanic component with increased horizontal resolution along the northwestern African coast, and its performance over the CCUS is assessed against relevant reanalysis data sets and compared with an ensemble of global climate models (GCMs) and an ensemble of atmosphere-only regional climate models (RCMs) in order to assess the role of the horizontal resolution. The coupled system reproduces the larger scale pattern of the CCUS and its latitudinal and seasonal variability over the coastal band, improving the GCMs outputs. Moreover, it shows a performance comparable to the ensemble of RCMs in representing the coastal wind stress and near-surface air temperature fields, showing the impact of the higher resolution and coupling for CCUS climate modelling. The model is able of properly reproducing mesoscale structures, being able to simulate the upwelling filaments events off Cape Ghir, which are not well represented in most of GCMs. Our results stress the ability of the regionally coupled model to reproduce the larger scale as well as mesoscale processes over the CCUS, opening the possibility to evaluate the climate change signal there with increased confidence., Open Access funding enabled and organized by Projekt DEAL. Ruben Vazquez was supported through a doctoral grant at the University of Ferrara and University of Cadiz. Dmitry Sein was supported in the framework of the state assignment of the Ministry of Science and Higher Education of Russia (No. 0128-2021-0014). This work used resources of the Deutsches Klimarechenzentrum (DKRZ) granted by its Scientific Steering Committee (WLA) under project ID ba0987.

Sea breezes are common and recurrent thermally-driven wind circulations formed in coastal areas under conditions of weak synoptic forcing. The different heat capacity between the land and the sea causes the thermal contrast needed for their formation. Therefore, the temperature changes at the surface of both the sea and the land influence the breezes characteristics. In this work, we investigate how sensitive are the sea breezes to changes in land cover and soil moisture, which may have a direct impact on the surface temperature inland. This is done through the design of different sensitivity experiments performed with the Weather Research and Forecasting (WRF) model, where we tested the effect of the land use and soil moisture modification. This was done through the simulation of a typical sea-breeze case study in the coastal area of the southwest of the Iberian Peninsula (Gulf of Cádiz). The differences among the experiments are compared spatially and confronted with observations from different meteorological towers at the coast and inland. A special emphasis is made on the changes observed in the area of the National Park of Doñana. This area is characterised by large shallow marshes with varying seasonal status and extensive rice crops. Thus, contrasting conditions of the surface are typically observed, which also depend on the previous hydrological conditions. Preliminary results highlight the importance of the correct representation of the surface inland to obtain a proper simulation of the sea-breeze system. Besides, new lines of research emerge to analyse the impacts caused by other potential modifications in the surface conditions of the land and the ocean (e.g., global change, urbanization, crop modification, changes in precipitation regimes or sea surface temperature, etc).

Climate simulations for the North Atlantic and Europe for recent and future conditions simulated with the regionally coupled ROM model are analyzed and compared to the results from the MPI-ESM. The ROM simulations also include a biogeochemistry and ocean tides. For recent climate conditions, ROM generally improves the simulations compared to the driving model MPI-ESM. Reduced oceanic biases in the Northern Atlantic are found, as well as a better simulation of the atmospheric circulation, notably storm tracks and blocking. Regarding future climate projections for the 21st century following the RCP 4.5 and 8.5 scenarios, MPI-ESM and ROM largely agree qualitatively on the climate change signal over Europe. However, many important differences are identified. For example, ROM shows an SST cooling in the Subpolar Gyre, which is not present in MPI-ESM. Under the RCP8.5 scenario, ROM Arctic sea ice cover is thinner and reaches the seasonally ice-free state by 2055, well before MPI-ESM. This shows the decisive importance of higher ocean resolution and regional coupling for determining the regional responses to global warming trends. Regarding biogeochemistry, both ROM and MPI-ESM simulate a widespread decline in winter nutrient concentration in the North Atlantic of up to similar to 35%. On the other hand, the phytoplankton spring bloom in the Arctic and in the North-Western Atlantic starts earlier, and the yearly primary production is enhanced in the Arctic in the late 21st century. These results clearly demonstrate the added value of ROM to determine more detailed and more reliable climate projections at the regional scale. Plain Language Summary We downscale present climate and future climate change projections for the North Atlantic and Europe using a regionally coupled Earth System Model including atmosphere, ocean, river runoff, and ocean biogeochemistry components. This approach allows us to attain higher spatial resolution and to a more accurate representation of key physical processes, yielding a better simulation of present climate at regional and local scales when compared to the driving global climate model. Future climate change projections show more detail at regional and local scale, mostly related to the improvement in the representation of orography and bathymetry. These improvements along with a better representation of the interactive ocean-atmosphere coupling lead to other remarkable differences with the driving global climate model: (1) colder Sea Surface Temperature in the Subpolar Gyre region, indicating a local convection collapse and a Atlantic Meridional Overturning Circulation slowdown; (2) a seasonal free-ice Arctic is reached by 2055 under RCP8.5 scenario, well before projected by the driving global climate model; and (3) stronger reduction in nutrients in the North Atlantic by the end of the 21st century. These results clearly demonstrate the added value of the regionally coupled model system to determine more reliable climate projections at the regional scale.

The identification and prioritization of pollution sources is essential to coastal zone management. This task is complicated when a variety of pollution sources are found and by limited data availability, which can result in an inconclusive assessment and differing public perceptions, ultimately hindering the progress of management actions. This is the case in Cartagena Bay (Colombia), a Caribbean hot-spot of pollution, which receives large freshwater discharges from the Magdalena River drained via the Dique Canal along with coastal industrial effluents and untreated domestic wastewater from parts of the coastal population. This study presents a methodology for the integrated assessment of anthropogenic pollution sources discharged into the coastal zone by estimating their loads and comparing their relative contributions to receiving coastal waters. Given the lack of available data on discharges and water quality, an integrated approach is applied by combining various methods of load estimation while emphasizing the importance of calculating confidence intervals for each load value. Pollution loads from nearby sources of domestic wastewater, coastal industrial effluents and continental runoff were assessed with respect to their contributions of coliforms, total suspended solids, nitrogen, phosphorus, and biological oxygen demand (BOD). Loads from the canal's surface runoff were calculated with monthly discharge and water quality data. Domestic loads were computed using GIS analyses of population and sewerage coverage in combination with export coefficients of daily load per capita. Industrial loads were estimated based on previous studies. Results show that each type of land-based source is responsible for different pollution impacts observed in Cartagena Bay. Occasionally, inadequate recreational water quality can be attributed to nearby sources of domestic wastewater, which contribute the highest coliform load (6.7 ± 3.9 × 1015 MPN/day). Continental runoff via the Dique Canal contributes the greatest sediment load (2.5 ± 1.9 × 103 t/day) causing the bay's turbid plumes and related ecosystem issues. Hypoxic conditions in the bay can be attributed to all three pollution sources which all discharge significant BOD loads (2–8 t/day), while the highest total phosphorus load comes from the Dique Canal (3.2 ± 2.4 t/day) and the highest nitrogen loads flow from the canal (3.7 ± 3.1 t·NO3-N/day) and the industrial sector (3.1 ± 4.1 t·N/day). Given that these loads are projected to increase in future years, this study highlights the importance of prioritization and mitigation in coastal pollution management and demonstrates a method that could be applied in other places with similar problems in the Wider Caribbean Region.

The Caribbean Sea provides significant ecosystem services to the livelihood and well-being of countries in the region. Protection of the marine ecosystem requires policy on coastal water quality that considers ecologically-relevant thresholds and has a scientific foundation linking land-based discharges with seawater quality. This study demonstrates a practical method for setting local-scale coastal water quality targets by applying this approach to Cartagena Bay, Colombia, and setting targets for end-of-river suspended sediment loads to mitigate offshore coral reef turbidity. This approach considers reef thresholds for suspended sediments and applies a field-calibrated 3D hydrodynamic-water quality model (MOHID) to link the marine thresholds to fluvial loads. Monitoring data showed that suspended sediments were consistently above the coral reef ecosystem threshold of 10 mg/l, and the model adequately reproduced field observations. It was shown that ecosystem thresholds could be maintained within the extent of the bay by reducing suspended sediment loads in the Dique Canal from current load estimates of 6.4 x 10(3) t/d (rainy season) and 4.3 x 10(3) t/d (transitional season) to target loads of 500-700 t/d, representing reductions of similar to 80-90%. These substantial reductions reflect ongoing issues in the Magdalena watershed which has experienced severe erosional conditions and intense deforestation over the past four decades. The presented method is practical for countries without access to long-term datasets, and could be applied to other parameters or discharge types. The method is particularly beneficial for developing site-specific targets, which are needed considering the natural and anthropogenic variability between different coastal zones and water bodies. International Development Research Centre, Ottawa, Canada [108747-001] EAFIT University, Corporacion Autonoma Regional del Canal del Dique (CARDIQUE) [15601] Erasmus Mundus Doctoral Programme in Marine and Coastal Management (MACOMA) info:eu-repo/semantics/publishedVersion

We assess the role of ocean feedbacks in the simulation of the present climate and on the downscaled climate change signal in the Mediterranean Sea with the regionally coupled model REMO-OASIS-MPIOM (ROM). The ROM oceanic component is global with regionally high horizontal resolution in the Mediterranean Sea. In our setup the Atlantic and Black Sea circulations are simulated explicitly. Simulations forced by ERA-Interim show a good representation of the present Mediterranean climate. Our analysis of the RCP8.5 scenario driven by MPI-ESM shows that the Mediterranean waters will be warmer and saltier across most of the basin by the end of the century. In the upper ocean layer temperature is projected to have a mean increase of 2.73 °C, while the mean salinity increases by 0.17 psu, presenting a decreasing trend in the Western Mediterranean, opposite to the rest of the basin. The warming initially takes place at the surface and propagates gradually to the deeper layers.

Coastal upwelling systems are very important from the socio-economic point of view due to their high productivity, but they are also vulnerable under changing climate. The impact of climate change on the Canary Current Upwelling System (CCUS) has been studied in recent years by different authors. However, these studies show contradictory results on the question whether coastal upwelling will be more intense or weak in the next decades. One of the reasons for this uncertainty is the low resolution of climate models, making it difficult to properly resolve coastal zone processes. To solve this issue, we propose the use of a high-resolution regional climate coupled model. In this work we evaluate the performance of the regional climate coupled model ROM (REMO-OASIS-MPIOM) in the influence zone of the CCUS as a first step towards a regional climate change scenario downscaling. The results were compared to the output of the global Max Planck Institute Earth System Model (MPI-ESM) showing a significant improvement.

Cartagena Bay, one of the Caribbean's hot spots of pollution, is an estuarine system connected to the Caribbean Sea by two straits. Large freshwater discharges from the Dique Canal into the south of the bay produce estuarine conditions strongly related to the seasonal variability of runoff from the Magdalena River watershed. The bay's seasonal conditions may be characterized by three seasons: strong winds/low runoff (Jan.-April), weak winds/intermediate runoff (May-Aug.), and weak winds/high runoff (Sept.-Dec.). This coastal zone is known to be impacted by land-based sources of pollution, including continental runoff, industrial effluents and domestic wastewater. However, previous studies have not sufficiently ascertained the spatio-temporal extent of this pollution. This study addresses the following research question: What is the current extent of water and sediment pollution in Cartagena Bay and which factors control its seasonal variability? Monthly seawater samples (Sept.2014-Aug.2015) were taken from surface and bottom depths at 16 stations in and around Cartagena Bay and analyzed for physical, chemical, and biological parameters. Surface sediments were sampled from the bay's bottom every three months and analyzed for various trace metals. Seasonal variability was observed in nearly all of the water quality parameters, with higher concentrations usually coinciding with the high runoff season. Potential pollution impacts are shown by wet-season averages of total suspended solids (45.0 +/- 89.5 mg/l), turbidity (26.1 +/- 59.7 NTU), biological oxygen demand (1.20 +/- 0.91 mg/l), chlorophyll-a (2.47 +/- 2.17 mu g/l), nitrate (171.1 +/- 112.6 mu g/l), phosphate (43.1 +/- 63.5 mu g/l), total phosphorus (85.3 +/- 77.2 mu g/l), phenol (2.9 +/- 17.4 mg/l), faecal coliforms (798 +/- 714 MPN/100 ml) and enterococci (32 +/- 30 CFU/100 ml) in excess of recommended threshold values for marine conservation and recreational adequacy. The bay's hypoxic conditions are evident with low dissolved oxygen concentrations (

Drifting Fish Aggregating Devices (dFADs) are small drifting platforms with an attached solar powered buoy that report their position with daily frequency via GPS. We use data of 9,440 drifting objects provided by a buoys manufacturing company, to test the predictions of surface current velocity provided by two of the main models: the NEMO model used by Copernicus Marine Environment Monitoring Service (CMEMS) and the HYCOM model used by the Global Ocean Forecast System (GOFS).

The ecosystem function of local fisheries holds great societal importance in the coastal zone of Cartagena, Colombia, where coastal communities depend on artisanal fishing for their livelihood and health. These fishing resources have declined sharply in recent decades partly due to issues of coastal water pollution. Mitigation strategies to reduce pollution can be better evaluated with the support of numerical hydrodynamic models. To model the hydrodynamics and water quality in Cartagena Bay, significant consideration must be dedicated to the process of light attenuation, given its importance to the bay’s characteristics of strong vertical stratification, turbid surface water plumes, algal blooms and hypoxia. This study uses measurements of total suspended solids (TSS), turbidity, chlorophyll-a (Chla) and Secchi depth monitored in the bay monthly over a 2-year period to calculate and compare the short-wave light extinction coefficient (Kd) according to nine different equations. The MOHID-Water model was used to simulate the bay’s hydrodynamics and to compare the effect of three different Kd values on the model’s ability to reproduce temperature profiles observed in the field. Simulations using Kd values calculated by equations that included TSS as a variable produced better results than those of an equation that included Chla as a variable. Further research will focus on evaluating other Kd calculation methods and comparing these results with simulations of different seasons. This study contributes valuable knowledge for eutrophication modelling which would be beneficial to coastal zone management in Cartagena Bay.

A bay's capacity to buffer fluvial fluxes between the land and sea is sensitive to hydrological changes that can affect its water renewal rates. In Cartagena Bay, Colombia, pollution issues have been associated with freshwater fluxes which are projected to increase in future years. This has led to plans to reduce freshwater flows by constructing upstream hydraulic doors. Given the influence of freshwater discharge on coastal water renewal, it is important to assess how these upstream changes will affect the bay's hydrodynamic processes. This study calibrated the 3D MOHID Water model, configured with a high-resolution mixed vertical discretization to capture the bay's characteristic processes of vertical stratification and mixing. A Lagrangian transport model was used to analyze the flow of passive particle tracers and calculate water renewal time scales. Mean residence times of 3-6 days and flushing times of 10-20 days for canal water were found, while mean residence times of 23-33 days and flushing times of 70-99 days were calculated for the bay's complete water volume. An assessment of future scenarios showed that increases in freshwater runoff would result in faster water renewal in the bay, while plans to decrease freshwater discharge would result in slower water renewal in the bay. It is therefore imperative that any plans for reducing fluvial fluxes into the bay be accompanied by the control of local pollution sources, which are abundant and could worsen the bay's water quality issues should water renewal times become longer. International Development Research Centre, Ottawa, Canada [108747-001] EAFIT University Corporacion Autonoma Regional del Canal del Dique (CARDIQUE) [15601] Erasmus Mundus Doctoral Programme in Marine and Coastal Management (MACOMA) Fundacion Hernan Echavarria Olozoga Escuela Naval de Cadetes "Almirante Padilla" University of Wyoming's surface observation service U. Lisboa's Marine Environment Technology Center (MARETEC) info:eu-repo/semantics/publishedVersion

An understanding of the interactions between biological, chemical and physical dynamics is especially important for the adequate conservation of the Underwater Cultural Heritage. However, while physical and chemical processes are relatively well-investigated, the biological communities associated with these habitats are poorly studied. We compared the sessile community developed on panels of different materials placed on two historical shipwrecks, the Fougueux and the Bucentaure, from the Battle of Trafalgar (October 1805). Six materials used at the construction of vessels at the 18th and 19th centuries were selected: copper, brass, cast iron, carbon steel, pine and oak. The sessile community developed on the panels was studied two and 15 months after their immersion at the water to determine the effects of materials and environmental conditions (sediments, waves, hydrodynamic conditions, temperature and salinity) on ecological succession and the possible implications at the conservation of historical shipwrecks. On the Fougueux, the environmental conditions more strongly influenced the biological succession than the material type, with pioneer colonisers dominating the communities in both sampling periods. On the Bucentaure, exposed to more stable environmental conditions, the sessile community showed differences between sampling periods and among materials at the end of the experiment. Under these more stable environmental conditions, the material type showed a higher influence on the sessile community. Species that produce calcareous concretions developed on metallic panels, but were absent on wood panels, where the shipworm Teredo navalis was more abundant. The relationship between environmental conditions, sessile organisms and material type can influence the conservation status of the archaeological sites.

The main features of the surface currents in the Strait of Gibraltar and Algeciras Bay are analyzed from the numerical results of three-dimensional hydrodynamic modeling, complemented and validated through observational data. The relative contributions of the main processes affecting the surface current patterns (i.e. mean background flows, barotropic tide, baroclinic internal waves, and wind regime) are described and interpreted, focusing on their effects on surface transport-dispersion processes, with special attention paid to the simulation and prediction of the evolution of oil spills and other marine pollutants in this sensitive environment in the context of coastal management. In general, the mean background surface flow promotes eastward transport in the Strait and re-circulation patterns within Algeciras Bay, with inflows and outflows mainly near the western and eastern coasts, respectively. The barotropic tide produces periodic reversals of water transport (and hence higher persistence and re-entrance processes) on the western side of the Strait and within the Bay, while its effects are generally weaker than the mean eastward flow in the eastern region. Baroclinic, tide-induced, short-period internal waves are responsible for occasional local high-divergence of the current field, with effects on the surface transport-dispersion processes. Finally, the wind regimes commonly present in this environment (mainly easterlies and westerlies) generally modulate the transport intensity in the Strait, while affecting more strongly the surface transport patterns within Algeciras Bay. Outputs from the developed metocean modeling system fed a Lagrangian particle-tracking model, validated by drifting-buoy data, to reproduce past oil spill events: the tanker Sea Spirit in the western Strait of Gibraltar (1990), and the ships Fedra and Tawe in Algeciras Bay (2008), each well documented and characterized by different metocean conditions and spill quantities. The predicted time-spatial distribution of the oil slicks and affected coasts were compared with available reports and photographs, showing that the strongly baroclinic oceanographic regime of the Strait of Gibraltar and Algeciras Bay demands a fully 3-D approach to simulate properly the behavior of surface pollutant spills in these environments, in order to achieve an efficient management by supporting risk assessment, contingency planning and palliation activities.

The output of a two-layer hydrodynamic model along a west–east section of the Gibraltar Strait is used to estimate tidal induced mixing between the Mediterranean and Atlantic water layers and to simulate the effects of mixing processes on biogeochemical fluxes and the pelagic community of the area. The hydrodynamic model is used to estimate interfacial mixing and water advection which drive the dynamics of the pelagic community. The model was run for 13 months, in order to analyse the effect of annual modulations in tidal amplitude on mixing. Incorporation of a third intermediate layer leads to a significant improvement in the model results, showing the necessity for a three layer circulation scheme when modelling biogeochemical processes in the Strait of Gibraltar. Pelagic processes are modelled using a simple Nutrient–Phytoplankton–Zooplankton (NPZ) model. The intense physical mixing and advection in the channel are the main influence on plankton dynamics in the area. It is found that residence times within the channel are so short that phytoplankton communities cannot grow appreciably during their transit. As a consequence, the use of a more sophisticated biogeochemical model does not lead to significant changes in the results obtained. According to the model, mixing over the Camarinal Sill causes an average of 16% of the out-flowing nutrients to be returned back to the Mediterranean. This fraction varies between 4% and 35% as a function of the tidal amplitude. The comparison of the model results with field data suggests that in order to obtain an accurate simulation of the plankton ecosystem dynamics in the strait, it is necessary to take into account the full horizontal flow, as recirculation and coast-channel interactions seems to be very important processes in explaining the biological patterns in the area.

The general circulation models used to simulate global climate typically feature resolution too coarse to reproduce many smaller scale processes, which are crucial to determining the regional responses to climate change. A novel approach to downscale climate change scenarios is presented which includes the interactions between the North Atlantic Ocean and the European shelves as well as their impact on the North Atlantic and European climate. The goal of this paper is to introduce the global ocean – regional atmosphere coupling concept and to show the potential benefits of this model system to simulate present day climate. A global ocean – sea ice – marine biogeochemistry model (MPIOM/HAMOCC) with regionally high horizontal resolution is coupled to an atmospheric regional model (REMO) and global terrestrial hydrology model (HD) via the OASIS coupler. Moreover, results obtained with ROM using NCEP/NCAR reanalysis and ECHAM5/MPIOM CMIP3 historical simulations as boundary conditions are presented and discussed for the North Atlantic and North European region. The validation of all the model components, i.e. ocean, atmosphere, terrestrial hydrology and ocean biogeochemistry is performed and discussed. The careful and detailed validation of ROM provides evidence that the proposed model system improves the simulation of many aspects of the regional climate, remarkably the ocean, even though some biases persist in other model components, thus leaving potential for future improvement. We conclude that ROM is a powerful tool to estimate possible impacts of climate change on the regional scale.