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Background Patch testing is an important investigation when dermatitis is unresponsive to, or worsened by, topical corticosteroid treatment. There is a balance to be struck between testing too many allergens, which is expensive, time consuming and risks causing sensitization, and testing too few, which risks missing the diagnosis. The current British Society for Cutaneous Allergy (BSCA) corticosteroid series comprises eight allergens and was last updated in February 2007. Aim To review and update the BSCA corticosteroid series. Methods We retrospectively analysed data from 16 patch test centres in the UK and Ireland for all patients who were patch tested to a corticosteroid series between August 2017 and July 2019. We recorded the allergens tested, the number and percentage tested to a corticosteroid series and the number of positive results for each allergen. We identified the allergens that test positive in ≥ 0.1% of selectively tested patients. Results Overall, 3531 patients were tested to a corticosteroid series in the 16 centres. The number of allergens tested ranged from 7 to 18 (mean 10). The proportion of patch test patients who were tested to a corticosteroid series ranged from 1% to 99%. Six allergens in the 2017 BSCA series tested positive in ≥ 0.1% of patients. Nine allergens not in the BSCA corticosteroid series tested positive in ≥ 0.1% of patients. Conclusion This audit demonstrates the importance of regular review of recommended series and the significant variations in practice. The new BSCA corticosteroid series that we recommend contains 13 haptens, with the addition of the patient’s own steroid creams as appropriate.

We present an analysis of the evolution of near-bed oxygen in the next century in the Northwest European Continental Shelf in a three-member ensemble of coupled physics-biogeochemistry models. The comparison between model results helps highlighting the biogeochemical mechanisms responsible for the observed deoxygenation trends and their response to climate drivers. While all models predict a decrease in near bed oxygen proportional to climate change intensity, the response is spatially heterogeneous, with hotspots of oxygen decline in the members with the most intense change, as well as areas where compensating mechanisms mitigate change. We separate the components of oxygen change associated to the warming effect on oxygen solubility from those due to the effects of changes in transport and ecosystem processes. We find that while warming is responsible for a mostly uniform decline throughout the shelf, changes in transport and ecosystem processes account for the detected heterogeneity. Hotspots of deoxygenation are associated with enhanced stratification that greatly reduces vertical transport. A major change in circulation in the North Sea is responsible for the onset of one such hotspot in the members characterised by intense climate change. Conversely, relatively shallow and well mixed coastal areas in the south experience an increase in net primary production that partially mitigates oxygen decline in all members. This work represents the first multi-model comparison addressing deoxygenation in the Northwest European Shelf and contributes to the understanding of the processes that drive deoxygenation in continental shelf ecosystems.

The Bay of Bengal is a dynamic region that experiences intense freshwater runoff, extreme meteorological events, and seasonal reversing surface currents. The region is particularly susceptible to anthropogenic climate change, driven in part by large air-sea fluxes, persistent freshwater stratification, and low overturning rates. Predicting how this ecosystem is likely to change in the future is paramount for planning effective mitigation strategies. Using a relocatable, coupled physics-ecosystem model (NEMO-ERSEM), we investigate the future changes in surface circulation and coastal nitrate pathways in the Bay of Bengal from 1980 to 2060, using a “business-as-usual" (RCP 8.5) climate change scenario. We find that future surface currents during the Summer and Fall Inter-monsoon seasons are reduced in the north/north-eastern Bay and strengthened in the south-western Bay. Coastal nitrate transports around the Bay mirror this asymmetric change, with coastal nitrate transports at 17.5oN decreasing by 185.7 mol N s-1, despite increased riverine runoff from the Ganges and Irrawaddy River systems. This results in a positive feedback loop whereby the northern Bay becomes progressively fresher and more nutrient-rich, strengthening the barrier layer and increasing the risk of toxic algal blooms and eutrophication events. Conversely, in the south-western Bay (12oN), coastal nitrate transports increase by 1317.8 mol N s-1, driven primarily by an intensified Sri Lanka Dome, that promotes localised diatom blooms despite negligible changes in regional river runoff. This work highlights the need for more rigorous ecosystem modelling and future scenario testing.

Coastal and shelf seas provide a diverse range of ecosystem services, which are often mediated by seasonal density stratification through its control on biogeochemical cycles. These seas are highly vulnerable to climate change and downscaling studies consistently project an increase in seasonal stratification over the next century, but without a clear explanation. Here we revisit a well-established theory of coastal ocean mixing and demonstrate with a new ensemble of downscaled simulations for the Northwest European continental shelf seas to 2100 that the increase of expansivity with temperature is sufficient to consistently increase the seasonal stratification. Where there is a closed balance between buoyancy input and mixing, small changes in expansivity are amplified to a large relative change in stratification. This simple link between global heating and stratification substantially reduces uncertainty in projections of this key parameter in seas around the world.

In response to an increasing demand for bespoke or tailored regional ocean modelling configurations, we outline fundamental principles and practices that can expedite the process to generate new configurations. The paper develops the principle of reproducibility and advocates adherence by presenting benefits to the community and user. The elements of this principle are reproducible workflows and standardised assessment, with additional effort over existing working practices being balanced against the added value generated. The paper then decomposes the complex build process, for a new regional ocean configuration, into stages and presents guidance, advice and insight for each component. This advice is compiled from across the NEMO (Nucleus for European Modelling of the Ocean) user community and sets out principles and practises that encompass regional ocean modelling with any model. With detailed and region-specific worked examples in Sects. 3 and 4, the linked companion repositories and DOIs all target NEMOv4. The aim of this review and perspective paper is to broaden the user community skill base and to accelerate development of new configurations in order to increase the time available for exploiting the configurations.

Identifying and quantifying the effects of climate change that alter the habitat overlap of marine predators and their prey population distributions is of great importance for the sustainable management of populations. This study uses Bayesian joint models with integrated nested Laplace approximation (INLA) to predict future spatial density distributions in the form of common spatial trends of predator–prey overlap in 2050 under the “business‐as‐usual, worst‐case” climate change scenario. This was done for combinations of six mobile marine predator species (gray seal, harbor seal, harbor porpoise, common guillemot, black‐legged kittiwake, and northern gannet) and two of their common prey species (herring and sandeels). A range of five explanatory variables that cover both physical and biological aspects of critical marine habitat were used as follows: bottom temperature, stratification, depth‐averaged speed, net primary production, and maximum subsurface chlorophyll. Four different methods were explored to quantify relative ecological cost/benefits of climate change to the common spatial trends of predator–prey density distributions. All but one future joint model showed significant decreases in overall spatial percentage change. The most dramatic loss in predator–prey population overlap was shown by harbor seals with large declines in the common spatial trend for both prey species. On the positive side, both gannets and guillemots are projected to have localized regions with increased overlap with sandeels. Most joint predator–prey models showed large changes in centroid location, however the direction of change in centroids was not simply northwards, but mostly ranged from northwest to northeast. This approach can be very useful in informing the design of spatial management policies under climate change by using the potential differences in ecological costs to weigh up the trade‐offs in decisions involving issues of large‐scale spatial use of our oceans, such as marine protected areas, commercial fishing, and large‐scale marine renewable developments., This study tests a range of analytical techniques to quantify ecological costs of climate change on habitat availability of predator–prey or competing mobile species. The study demonstrates how to detect environmentally sensitive habitat areas and is highly useful for habitat management policies under climate change.

Issue sup1: Copernicus Marine Service Ocean State Report, Issue 5 Supplement.-- Karina von Schuckmann (Editor), Pierre-Yves Le Traon (Editor), Neville Smith (Chair) (Review Editor), Ananda Pascual (Review Editor), Samuel Djavidnia (Review Editor), Jean-Pierre Gattuso (Review Editor), Marilaure Grégoire (Review Editor), The work was supported by the Copernicus Marine Environment Monitoring Service (CMEMS) LATEMAR project. CMEMS is implemented by Mercator Ocean in the framework of a delegation agreement with the European Union. This work has also been conducted as part of the bilateral project EOLO-1 (“Extreme Oceanic waves during tropical, tropical-like, and bomb cyclones”) between CNR-ISMAR and the University of Tokyo (Japan; Prof. Takuji Waseda). Antonio Ricchi funding have been provided via the PON “AIM” - Attraction and international mobility program AIM1858058. Joanna Staneva acknowledges H2020 IMMERSE Project, Arno Behrens was supported by CMEMS Waveflow project and G. Gayer by ESA Black Sea and Danube Regional Initiative (EO4BS).

We use a recently developed spectrally resolved bio-optical module to better represent the interaction between the incoming irradiance and the heat fluxes in the upper ocean within the (pre-)operat...

The Indian Ocean is a dynamic region that is heavily influenced by immense freshwater runoff, extreme meteorological events and the seasonal reversal of monsoonal currents. Providing essential resources for over one-third of the global population, the Northern Indian Ocean is a key area of research: increased freshwater run-off, low overturning velocities and high air-sea fluxes result in the region being highly susceptible to climate fluctuations, and execess nutrients, particularly nitrates accumulated through agricultural run-off, directly influence marine biogeochemical cycles. The South Asia Nitrogen Hub (SANH) is a GCRF project designed to assess, monitor and predict the physical and biogeochemical response of the Northern Indian Ocean to such anthropogenic changes. To address key questions in SANH, a relocatable physical-biogeochemical (NEMO-ERSEM) was configured across the region, which includes the Eastern Arabian Sea and the Bay of Bengal. A 22-year hindcast run (1993-2015) at ~11km resolution allows the physical-biogeochemical processes (including from mesoscale eddies, extreme meteorological events and varying runoff) to be viewed at scale that is otherwise impossible with observational campaigns. In conjunction with the large-scale model domain, 6 smaller high-resolution (~1-2km) coastal models were configurated around the Indian subcontinent, allowing a more focussed view at processes that directly impact coastal populations. Here, we will present initial results from the large-scale hindcast run, the coastal regions, and explore the advantages and caveats of relocatable modelling.

The marine environment experiences temperature variability both in the short and long term due to a combination of variable surface heating, ocean transport and mixing effects. The impact of temperature anomalies on the marine ecosystem depends on their duration and amplitude compared with timescales of the ecological response and the susceptibility of various components of the ecosystem to the change. Even relatively short events can affect reproduction and growth, and potentially cause mortality when organism tolerance limits are exceeded.We focus on sustained (lasting longer than 5 days) temperature events that are extreme relative to the phase of the seasonal cycle and consider both heatwaves and cold-spells. We used daily-mean near-bed temperatures from the CMEMS (https://marine.copernicus.eu/) northwest European Shelf reanalysis and analysis/forecast simulations to identify heatwaves and cold-spells for the period 1993 to 2019. Monthly fisheries landings data for 1993 to 2016 from the Cefas Fisheries Activity Database for England and Wales (https://www.gov.uk/guidance/fishing-activity-and-landings-data-collection-and-processing) were analysed to identify potential impacts of the extreme temperature events on fish and shellfish.Widespread heatwaves and cold-spells occurred in the southern North Sea throughout the period 1993 to 2019 but with no significant trends in the extent or magnitude of events. Winter cold-spells occurred in 1994, 1996, 1997, 2010, 2011, 2013 and 2018 and there were widespread heatwaves in 1998, 2002, 2003, 2006, 2007 and 2014 to 2019. Statistical analysis of the fisheries landings data identified a link between extreme temperature events and key fish and shellfish stocks in the North Sea. Catches of sole and sea bass increased in years with cold-spells, while catches of red mullet and edible crabs decreased. For heatwaves, the impact on fisheries catch data lagged the temperature events by five years: sole, European lobster and sea bass catches increased whilst red mullet catches reduced.

We use modelling and assimilation tools to explore the impact of biogeochemistry on physics in the shelf sea environment, using North-West European Shelf (NWES) as a case study. We demonstrate that such impact is significant: the attenuation of light by biogeochemical substances heats up the upper 20 m of the ocean by up to 1 °C and by a similar margin cools down the ocean within the 20–200 m range of depths. We demonstrate that these changes to sea temperature influence mixing in the upper ocean and feed back into marine biology by influencing the timing of the phytoplankton bloom, as suggested by the critical turbulence hypothesis. We compare different light schemes representing the impact of biogeochemistry on physics, and show that the physics is sensitive to both the spectral resolution of radiances and the represented optically active constituents. We introduce a new development into the research version of the operational model for the NWES, in which we calculate the heat fluxes based on the spectrally resolved attenuation by the simulated biogeochemical tracers, establishing a two-way coupling between biogeochemistry and physics. We demonstrate that in the late spring–summer the two-way coupled model increases heating in the upper oceanic layer compared to the existing model and improves by 1–3 days the timing of the simulated phytoplankton bloom. This improvement is relatively small compared with the existing model bias in bloom timing, but is sufficient to have a visible impact on model skill in the free run. We also validate the skill of the two-way coupling in the context of the weakly coupled physical–biogeochemical assimilation currently used for operational forecasting of the NWES. We show that the change to the skill is negligible for analyses, but it remains to be seen how much it differs for the forecasts.

Climate change is expected to cause important changes in ocean physics, which will in turn have important effects on the marine ecosystems. The ReCICLE project (Resolving Climate Impacts on shelf and CoastaL seas Ecosystems) aims to identify and quantify the envelope of response to climate change of lower trophic level shelf-sea ecosystems and their functional interactions, in order to assess the vulnerability of ecosystem goods and services in the UK shelf seas. The central tool for this work is an ensemble of coupled hydrodynamic-biogeochemical ecosystem models NEMO-ERSEM Atlantic Margin Model configuration at 7 km horizontal resolution (AMM7), forced by different CIMP5 global climate change models to generate downscaled scenarios for future decades.Changes in connectivity patterns are expected to affect coastal populations of marine organisms in shelf seas. Holt et al 2018 (GRL https://doi.org/10.1029/2018GL078878) showed the potential for radical reorganization of the North Sea circulation in earlier simulations. To assess this particular issue particle tracking experiments are carried out during two 10 year time slices, in the recent past (2000-2010) and in the future (2040-2050) in ensemble members of the ReCICLE AMM7 regional downscaling showing contrasting circulation patterns. Surface particles were uniformly seeded in the UK shelf seas every month and tracked for 30 days. The resulting particle trajectories are analysed with cluster analysis technics aiming to determine if persistent oceanographic boundaries re-arrange in the future climate scenarios. The ecological effects of circulation and water masses changes in the future ocean are discussed from a Lagrangian perspective.

Dissolved oxygen in the ocean is an indicator of water quality and low concentrations can threaten ecosystem health. The main sources of marine oxygen are diffusion from the atmosphere and phytoplankton photosynthesis. Biological respiration and decomposition act to reduce oxygen concentrations. Under conditions of vertical stratification, the water column below the pycnocline is isolated from oxygen exchange with the atmosphere, photosynthesis may be limited by light availability and oxygen concentrations decrease. Climate change influences the oxygen cycle in two ways: 1) changing the hydrodynamic climate and 2) affecting rates of biogeochemical processes. The hydrodynamic climate affects the nutrient supply and so controls phytoplankton production while changes to water column stratification affects vertical mixing. Gas solubility decreases with increasing temperature so that oxygen uptake from the atmosphere is expected to decrease under increasing oceanic temperatures. Biological cycling rates increase with increasing temperature affecting photosynthesis, respiration and bacterial decomposition. It is not obvious whether changes in oxygen concentrations due to changing ecosystem processes will mitigate or reinforce the projected reduction from solubility changes.The Northwest European Continental shelf (NWES) is a region of the northeast Atlantic that experiences seasonal stratification. We use the physics-biogeochemical model NEMO-ERSEM to study near-bed oxygen concentrations on the NWES under a high greenhouse gas emissions scenario (Representative Concentration Pathway (RCP) 8.5). We show that much of the NWES could experience low oxygen concentrations by 2100 and assess the relative impacts of changing temperature and ecosystem processes. Until about 2040 the impact of solubility dominates the oxygen change. The mean near-bed oxygen concentration is projected to decrease by 6.3% by 2100, of which 73% is due to solubility changes and the remainder to changes in the ecosystem. In the oxygen-depleted region in the eastern North Sea, 77% of the near-bed oxygen reduction is due to ecosystem processes.

The North West European shelf-break acts as a barrier to the transport and exchange between the open ocean and the shelf seas. The strong spatial variability of these exchange processes is hard to fully explore using observations, and simulations generally are too coarse to simulate the fine-scale processes over the whole region. In this context, under the FASTNEt programme, a new NEMO configuration of the North West European Shelf and Atlantic margin at 1/60° (∼1.8km) has been developed, with the objective to better understand and quantify the seasonal and interannual variability of shelf break processes. The capability of this configuration to reproduce the seasonal cycle in SST, the barotropic tide, and fine-resolution temperature profiles is assessed against a basin-scale (1/12°, ∼9km) configuration and a standard regional configuration (7 km resolution). The seasonal cycle is well reproduced in all configurations though the fine-resolution allows the simulation of smaller scale processes. Time-series of temperature at various locations on the shelf show the presence of internal waves with a strong spatio-temporal variability. Spectral analysis of the internal waves reveals peaks at the diurnal, semi-diurnal, inertial and quarter-diurnal bands, which are only realistically reproduced in the new configuration. Tidally induced pycnocline variability is diagnosed in the model and shown to vary with the spring neap cycle with mean displacement amplitudes in excess of 2m for 30% of the stratified domain. With sufficiently fine-resolution, internal tides are shown to be generated at numerous bathymetric features resulting in a complex pycnocline displacement superposition pattern.

We describe the physical model component of the standard Coastal Ocean version 5 configuration (CO5) of the European north-west shelf (NWS). CO5 was developed jointly between the Met Office and the National Oceanography Centre. CO5 is designed with the seamless approach in mind, which allows for modelling of multiple timescales for a variety of applications from short-range ocean forecasting to climate projections. The configuration constitutes the basis of the latest update to the ocean and data assimilation components of the Met Office's operational Forecast Ocean Assimilation Model (FOAM) for the NWS. A 30.5-year non-assimilating control hindcast of CO5 was integrated from January 1981 to June 2012. Sensitivity simulations were conducted with reference to the control run. The control run is compared against a previous non-assimilating Proudman Oceanographic Laboratory Coastal Ocean Modelling System (POLCOMS) hindcast of the NWS. The CO5 control hindcast is shown to have much reduced biases compared to POLCOMS. Emphasis in the system description is weighted to updates in CO5 over previous versions. Updates include an increase in vertical resolution, a new vertical coordinate stretching function, the replacement of climatological riverine sources with the pan-European hydrological model E-HYPE, a new Baltic boundary condition and switching from directly imposed atmospheric model boundary fluxes to calculating the fluxes within the model using a bulk formula. Sensitivity tests of the updates are detailed with a view toward attributing observed changes in the new system from the previous system and suggesting future directions of research to further improve the system.

Dissolved oxygen concentrations in the ocean are declining on a global scale. However, the impact of climate change on oxygen in shelf seas is not well understood. We investigate potential future changes in oxygen on the northwest European continental shelf under a business as usual greenhouse gas emissions scenario (Representative Concentration Pathway RCP8.5). Regions of the European shelf are thermally stratified from spring to autumn, which can cause oxygen depletion in sub-pycnocline waters. A transient climate-forced model simulation is used to study how the temperature, salinity and concentration of near bed dissolved oxygen change over the 21st century. In warming and freshening water, the oxygen concentration declines in all shelf regions. The climate change signal emerges first in salinity, then in temperature and finally in near bed oxygen. Regions that currently experience oxygen depletion (the eastern North Sea, Celtic Sea and Armorican shelf) become larger in the future scenario and oxygen depletion lasts longer. Solubility changes, caused by changes in temperature and salinity, are the dominant cause of reducing near bed oxygen concentrations in many regions. Until about 2040 the impact of solubility dominates over the effects of the evolving ecosystem. However, in the eastern North Sea by 2100, the effect of ecosystem change is generally larger than that of solubility. In the Armorican Shelf and Celtic Sea the ecosystem changes partially mitigate the oxygen decline caused by solubility changes. Over the 21st century the mean near bed oxygen concentration on the European shelf is projected to decrease by 6.3%, of which 73% is due to solubility changes and the remainder to changes in the ecosystem. For monthly minimum oxygen the decline is 7.7% with the solubility component being 50% of the total.

Urticaria is an inflammatory complaint characterized by short-lived skin swellings termed ‘wheals’ or ‘hives’. It can be divided into acute urticaria, where the disease has an abrupt onset, and chronic urticaria, where wheals have occurred on a regular basis for over 6 weeks. Physical urticaria is a subgroup of chronic urticaria where an underlying external/physical trigger can be identified, while contact urticaria arises from contact with a chemical substance on the skin or mucous membranes. Angiooedema represents a similar process affecting the deeper dermal tissue and has a predilection for the skin around the eyes and mouth. It may occur in association with urticaria or as an isolated complaint.

We demonstrate for the first time a direct oceanic link between climate‐driven change in the North Atlantic and Arctic oceans and the circulation of the northwest European shelf‐seas. Downscaled scenarios show a shutdown of the exchange between the Atlantic and the North Sea, and a substantial decrease in the circulation of the North Sea in the second half of the 21st Century. The northern North Sea inflow decreases from 1.2‐1.3Sv (1Sv=106 m3s‐1) to 0.0‐0.6Sv with Atlantic water largely bypassing the North Sea. This is traced to changes in oceanic haline stratification and gyre structure, and to a newly identified circulation‐salinity feedback. The scenario presented here is of a novel potential future state for the North Sea, with wide‐ranging environmental management and societal impacts. Specifically, the sea would become more estuarine and susceptible to anthropogenic influence with an enhanced risk of coastal eutrophication. Plain Language Summary Little is known about how climate change might impact the long‐term circulation of shelf‐seas. In this paper, we use a high‐resolution shelf‐sea model to demonstrate how end‐of‐century changes in the wider ocean can lead to a substantial reduction in the flow of water from the North Atlantic into the North Sea. This, in turn, reduces the circulation of this sea, which becomes more influenced by rivers and less by oceanic waters. River water generally contains higher levels of nutrients and our simulations show that this future scenario leads to enhanced levels of phytoplankton growth in local regions of the North Sea. This may lead to undesirable disturbances to the marine ecosystems, such as depletion of oxygen near the seabed. The reduced circulation would also disrupt the transport of larvae around the sea and lead to increased retention of pollutants. The reduction in circulation arises from several causes relating to increased density layering at the continental shelf‐edge; changes in the large‐scale ocean circulation and salinity; and disruption of the density‐driven circulation of the North Sea. By exploring these novel future scenarios, we emphasize the need to understand better the many ways climate change can influence the marine environment and its ecosystems.

This paper describes the next generation ocean forecast model for the European North West Shelf, which will become the basis of operational forecasts in 2018. This new system will provide a step change in resolution, and therefore our ability to represent small scale processes. The new model has a resolution of 1.5 km, compared with a grid spacing of 7 km in the current operational system. AMM15 (Atlantic Margin Model, 1.5 km) is introduced as a new regional configuration of NEMO v3.6. Here we describe the technical details behind this configuration, with modifications appropriate for the new high resolution domain. Results from a 30 year non-assimilative run, using the AMM15 domain, demonstrate the ability of this model to represent the mean state and variability of the region. Overall, there is an improvement in the representation of the mean state across the region, suggesting similar improvements may be seen in the future operational system. However, the reduction in seasonal bias is greater off-shelf than on-shelf. In the North Sea, biases are largely unchanged. Since there has been no change to the vertical resolution or parameterisation schemes, performance improvements are not expected in regions where stratification is dominated by vertical processes, rather than advection. This highlights the fact that increased horizontal resolution will not lead to domain-wide improvements. Further work is needed to target bias reduction across the North West Shelf region.

Marine space is about to get even busier. Around the globe many countries are looking to use their ocean space, especially their coastal marine areas, for the extraction of renewable energy from the wind, waves and tides. This large scale use of renewable energy will help global reductions in CO2 release and ultimately reduce the risk of ecological damage due to sever climate change. However the cumulative effect of large scale developments and the range of methods to extract energy from the oceans will cause local changes in physical mixing properties and the effects will be felt locally throughout the trophic chain. How can we assess the ecological costs and benefits of these contrasting pressures on our marine systems such that our choices in where we allow the placement of large scale energy extraction is ultimately ecological beneficial? In this work we suggest that the use of statistical joint models; spatially explicit models that simultaneous explore the distributions of mobile predator and prey species such as pelagic fish and seabird and marine mammal species are a most useful tool in the calculation of the degree of overlap in these species now and in future predictions with climate change, energy extraction and both climate change and energy extraction. The contrasting degree of spatial overlap in these different scenarios will allow the estimate on the ecological costs and benefits of large scale extraction of marine renewable energy.

As oil reserves in established basins become depleted, exploration and production moves towards relatively unexploited areas, such as deep waters off the continental shelf. The Faroe-Shetland Channel (FSC, NE Atlantic) and adjacent areas have been subject to increased focus by the oil industry. In addition to extreme depths, metocean conditions in this region characterise an environment with high waves and strong winds, strong currents, complex circulation patterns, sharp density gradients, and large small- and mesoscale variability. These conditions pose operational challenges to oil spill response and question the suitability of current oil spill modelling frameworks (oil spill models and their forcing data) to adequately simulate the behaviour of a potential oil spill in the area. This article reviews the state of knowledge relevant to deepwater oil spill modelling for the FSC area and identifies knowledge gaps and research priorities. Our analysis should be relevant to other areas of complex oceanography.

We describe the physical model component of the standard Coastal Ocean version 5 configuration (CO5) of the European North West Shelf (NWS). CO5 was developed jointly between the Met Office and the National Oceanography Centre. CO5 is designed with the seamless approach in mind, which allows for modeling of multiple timescales for a variety of applications from short-range ocean forecasting through to climate projections. The configuration constitutes the basis of the latest update to the ocean and data assimilation components of the Met Office's operational Forecast Ocean Assimilation Model (FOAM) for the NWS. A 30.5 year non-assimilating control hindcast of CO5 was integrated from January 1981 to June 2012. Sensitivity simulations were conducted with reference to the control run. The control run is compared against a previous non-assimilating Proudman Oceanographic Laboratory Coastal Ocean Modelling System (POLCOMS) hindcast of the NWS. The CO5 control hindcast is shown to have much reduced biases compared to POLCOMS. Emphasis in the system description is weighted to updates in CO5 over previous versions. Updates include an increase in vertical resolution, a new vertical coordinate stretching function, the replacement of climatological riverine sources with the pan-European hydrological model E-HYPE, a new Baltic boundary condition and switching from directly imposed atmospheric model boundary fluxes to calculating the fluxes within the model using bulk formula. Sensitivity tests of the updates are detailed with a view to attributing observed changes in the new system from the previous system and suggesting future directions of research to further improve the system.

Eutrophication is a process resulting from an increase in anthropogenic nutrient inputs from rivers and other sources, the consequences of which can include enhanced algal biomass, changes in plankton community composition and oxygen depletion near the seabed. Within the context of the Marine Strategy Framework Directive, indicators (and associated threshold) have been identified to assess the eutrophication status of an ecosystem. Large databases of observations (in situ) are required to properly assess the eutrophication status. Marine hydrodynamic/ecosystem models provide continuous fields of a wide range of ecosystem characteristics. Using such models in this context could help to overcome the lack of in situ data, and provide a powerful tool for ecosystem-based management and policy makers. Here we demonstrate a methodology that uses a combination of model outputs and in situ data to assess the risk of eutrophication in the coastal domain of the North Sea. The risk of eutrophication is computed for the past and present time as well as for different future scenarios. This allows us to assess both the current risk and its sensitivity to anthropogenic pressure and climate change. Model sensitivity studies suggest that the coastal waters of the North Sea may be more sensitive to anthropogenic rivers loads than climate change in the near future (to 2040).

The increase in atmospheric CO2 is a dual threat to the marine environment: from one side it drives climate change, leading to modifications in water temperature, circulation patterns and stratification intensity; on the other side it causes a decrease in marine pH (ocean acidification, or OA) due to the increase in dissolved CO2. Assessing the combined impact of climate change and OA on marine ecosystems is a challenging task. The response of the ecosystem to a single driver can be highly variable and remains still uncertain; additionally the interaction between these can be either synergistic or antagonistic. In this work we use the coupled oceanographic–ecosystem model POLCOMS-ERSEM driven by climate forcing to study the interaction between climate change and OA. We focus in particular on carbonate chemistry, primary and secondary production. The model has been run in three different configurations in order to assess separately the impacts of climate change on net primary production and of OA on the carbonate chemistry, which have been strongly supported by scientific literature, from the impact of biological feedbacks of OA on the ecosystem, whose uncertainty still has to be well constrained. The global mean of the projected decrease of pH at the end of the century is about 0.27 pH units, but the model shows significant interaction among the drivers and high variability in the temporal and spatial response. As a result of this high variability, critical tipping point can be locally and/or temporally reached: e.g. undersaturation with respect to aragonite is projected to occur in the deeper part of the central North Sea during summer. Impacts of climate change and of OA on primary and secondary production may have similar magnitude, compensating in some area and exacerbating in others.

James Herbert Sydney Wakelin (“Jimmy”) qualified in his hometown of Cardiff and then served as squadron leader in the Royal Air Force at St Athan from 1948 to 1950. While working as a house surgeon …

Increasing numbers of regional climate change scenario assessments have become available for the North Sea. A critical review of the regional studies has helped identify robust changes, challenges, uncertainties and specific recommendations for future research. Coherent findings from the climate change impact studies reviewed in this chapter include overall increases in sea level and ocean temperature, a freshening of the North Sea, an increase in ocean acidification and a decrease in primary production. However, findings from multi-model ensembles show the amplitude and spatial pattern of the projected changes in sea level, temperature, salinity and primary production are not consistent among the various regional projections and remain uncertain. Different approaches are used to downscale global climate change impacts, each with advantages and disadvantages. Regardless of the downscaling method employed, the regional studies are ultimately affected by the forcing global climate models. Projecting regional climate change impacts on biogeochemistry and primary production is currently limited by a lack of consistent downscaling approaches for marine and terrestrial impacts. Substantial natural variability in the North Sea region from annual to multi-decadal time scales is a particular challenge for projecting regional climate change impacts. Natural variability dominates long-term trends in wind fields and strongly wind-influenced characteristics like local sea level, storm surges, surface waves, circulation and local transport pattern. Multi-decadal variations bias changes projected for 20- or 30-year time slices. Disentangling natural variations and regional climate change impacts is a remaining challenge for the North Sea and reliable predictions concerning strongly wind-influenced characteristics are impossible.

International audience; Regional seas are potentially highly vulnerable to climate change, yet are the most directly societally important regions of the marine environment. The combination of widely varying conditions of mixing, forcing, geography (coastline and bathymetry) and exposure to the open-ocean makes these seas subject to a wide range of physical processes that mediates how large scale climate change impacts on these seas’ ecosystems. In this paper we explore the response of five regional sea areas to potential future climate change, acting via atmospheric, oceanic and terrestrial vectors. These include the Barents Sea, Black Sea, Baltic Sea, North Sea, Celtic Seas, and are contrasted with a region of the Northeast Atlantic. Our aim is to elucidate the controlling dynamical processes and how these vary between and within these seas. We focus on primary production and consider the potential climatic impacts on: long term changes in elemental budgets, seasonal and mesoscale processes that control phytoplankton’s exposure to light and nutrients, and briefly direct temperature response. We draw examples from the MEECE FP7 project and five regional model systems each using a common global Earth System Model as forcing. We consider a common analysis approach, and additional sensitivity experiments.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.

In this paper we clearly demonstrate that changes in oceanic nutrients are a first order factor in determining changes in the primary production of the northwest European continental shelf on time scales of 5–10 yr. We present a series of coupled hydrodynamic ecosystem modelling simulations, using the POLCOMS-ERSEM system. These are forced by both reanalysis data and a single example of a coupled ocean-atmosphere general circulation model (OA-GCM) representative of possible conditions in 2080–2100 under an SRES A1B emissions scenario, along with the corresponding present day control. The OA-GCM forced simulations show a substantial reduction in surface nutrients in the open-ocean regions of the model domain, comparing future and present day time-slices. This arises from a large increase in oceanic stratification. Tracer transport experiments identify a substantial fraction of on-shelf water originates from the open-ocean region to the south of the domain, where this increase is largest, and indeed the on-shelf nutrient and primary production are reduced as this water is transported on-shelf. This relationship is confirmed quantitatively by comparing changes in winter nitrate with total annual nitrate uptake. The reduction in primary production by the reduced nutrient transport is mitigated by on-shelf processes relating to temperature, stratification (length of growing season) and recycling. Regions less exposed to ocean-shelf exchange in this model (Celtic Sea, Irish Sea, English Channel, and Southern North Sea) show a modest increase in primary production (of 5–10%) compared with a decrease of 0–20% in the outer shelf, Central and Northern North Sea. These findings are backed up by a boundary condition perturbation experiment and a simple mixing model.

The ocean plays an important role in regulating the climate, acting as a sink for carbon dioxide, perturbing the carbonate system and resulting in a slow decrease of seawater pH. Understanding the dynamics of the carbonate system in shelf sea regions is necessary to evaluate the impact of Ocean Acidification (OA) in these societally important ecosystems. Complex hydrodynamic and ecosystem coupled models provide a method of capturing the significant heterogeneity of these areas. However rigorous validation is essential to properly assess the reliability of such models. The coupled model POLCOMS–ERSEM has been implemented in the North Western European shelf with a new parameterization for alkalinity explicitly accounting for riverine inputs and the influence of biological processes. The model has been validated in a like with like comparison with North Sea data from the CANOBA dataset. The model shows good to reasonable agreement for the principal variables, physical (temperature and salinity), biogeochemical (nutrients) and carbonate system (dissolved inorganic carbon and total alkalinity), but simulation of the derived variables, pH and pCO2, are not yet fully satisfactory. This high uncertainty is attributed mostly to riverine forcing and primary production. This study suggests that the model is a useful tool to provide information on Ocean Acidification scenarios, but uncertainty on pH and pCO2 needs to be reduced, particularly when impacts of OA on ecosystem functions are included in the model systems.

As our reliance upon numerical models for forecasting environmental conditions increases, so does our need to quantitatively analyse their performance. Often, a single metric approach is adopted, the choice of which is dependent upon the application for which the model output are to be used. Here we present a multi-metric verification approach to analyse the spatial and temporal performance of a hydrodynamic ecosystem model. The metrics allow us to investigate the model's ability to predict the inter- and intra-annual spatial variations and are used to evaluate surface chlorophyll- a estimates from the POLCOMS-ERSEM model, using satellite Earth observation data from NASA's MODIS-Aqua sensor. The study focuses on a region of the north east Atlantic which encompasses both open ocean and shelf seas, presenting a sizeable challenge for any model. The metrics reveal that the model is able to capture the mean annual chlorophyll- a signal (as exhibited in the Earth observational data) and has the capability to describe medium scale spatial variations. The seasonal signal exhibited in the Earth observation data is not apparent in the model fields. Possible reasons for the mis-match between the Earth observation and model data are discussed. Notwithstanding these issues, the model exhibits predictive skill during the northern hemisphere summer months for a range of chlorophyll- a concentrations. This multi-metric evaluation approach provides a method for the rigorous evaluation of the spatial and temporal accuracy of the hydrodynamic ecosystem model.

In this paper the results from a workshop of the OSPAR Intersessional Correspondence Group on Eutrophication Modelling (ICG-EMO) held in Lowestoft in 2007 are presented. The aim of the workshop was to compare the results of a number of North Sea ecosystem models under different reduction scenarios. In order to achieve comparability of model results the participants were requested to use a minimum spin-up time, common boundary conditions which were derived from a wider-domain model, and a set of common forcing data, with special emphasis on a complete coverage of river nutrient loads. Based on the OSPAR requirements river loads were derived, taking into account the reductions already achieved between 1985 and 2002 for each country. First, for the year 2002, for which the Comprehensive Procedure was applied, the different horizontal distributions of net primary production are compared. Furthermore, the differences in the net primary production between the hindcast run and the 50% nutrient reduction runs are displayed. In order to compare local results, the hindcast and reduction runs are presented for selected target areas and scored against the Comprehensive Procedure assessment levels for the parameters DIN, DIP and chlorophyll. Finally, the temporal development of the assessment parameter bottom oxygen concentration from several models is compared with data from the Dutch monitoring station Terschelling 135. The conclusion from the workshop was that models are useful to support the application of the OSPAR Comprehensive Procedure. The comparative exercise formulated specifically for the workshop required models to be evaluated for pre-defined target areas previously classified as problem areas according to the first application of the Comprehensive Procedure. The responsiveness of the modelled assessment parameters varied between different models but in general the parameter showed a larger response in coastal rather than in offshore waters, which in some cases lead to the goal to achieve a non-problem status. Therefore, the application of the Comprehensive Procedure on model results for parameter assessment opens a new potential in testing eutrophication reduction measures within the North Sea catchment. As a result of the workshop further work was proposed to confirm and bolster confidence in the results. One general field of difficulty appeared to be the model forcing with SPM data in order to achieve realistic levels of light attenuation. Finally, effects of the prescribed spin-up procedure are compared against a long-term run over many years and consequences on the resulting initial nutrient concentrations are highlighted. (C) 2010 Elsevier B.V. All rights reserved.

Changes in global atmospheric conditions have the potential to substantially influence shelf sea environments with far reaching consequences for their ecosystems. Here we focus on the northwest European continental shelf, and review the mechanisms by which climate change might affect the temperature, salinity and stratification of this shelf sea. We explore results from a single pair of Proudman Oceanographic Laboratory Coastal Ocean Modelling System (POLCOMS) simulations forced by the Hadley Centre regional climate model, for conditions typical of 1961–1990 and 2070–2098, under a ‘business as usual’ emissions scenario (SRES A1B). This provides a single, physically plausible, representation of the future and a consistent representation of the recent past. Comparing these simulations, the shelf sea regions of this model are shown to warm substantially more than the open-ocean, by between 1.5 and 4 °C depending on location. Across the whole domain the surface waters are projected to be ∼0.2 p.s.u. fresher by the end of the 21st century. The strength of seasonal stratification is shown to increase by ∼20% on the shelf, compared with 20–50% in the open-ocean. The former being controlled by temperature and the latter by salinity. In shelf seas away from the direct influence of river discharge, stratification is projected to start ∼5 days earlier and breakdown ∼5–10 days later each year, hence extending the stratified period. An ERA-40 re-analysis forced simulation provides a reference, along with validation from gridded monthly mean data from the ICES data base.

The role of the North Atlantic Oscillation (NAO) in effecting changes in winter extreme high and low waters and storm surges in UK waters has been investigated with the use of a depth-averaged tide+surge numerical model. Spatial patterns of correlation of extreme high and low waters (extreme still water sea levels) with the NAO index are similar to those of median or mean sea level studied previously. Explanations for the similarities, and for differences where they occur, are proposed. Spatial patterns of correlations of extreme high and low and median surge with the NAO index are similar to the corresponding extreme sea-level patterns. Suggestions are made as to which properties of surges (frequency, duration, magnitude) are linked most closely to NAO variability. Several climate models suggest higher (more positive) average values of NAO index during the next 100 years. However, the impact on the UK coastline in terms of increased flood risk should be low (aside from other consequences of climate change such as a global sea-level rise) if the existing relationships between extreme high waters and NAO index are maintained.

A 1/12° by 1/12° two-dimensional, hydrodynamic tide–surge model for the Mediterranean Sea is used to model two storm surge events in the Adriatic Sea. The impact of meteorological forcing on the model results is investigated using three different sources of data: observations obtained from the UK Meteorological Office, operational analysis model data from the European Centre for Medium Range Weather Forecasting and a local area model for the Adriatic region obtained from Agenzia Regionale Prevenzione e Ambiente dell'Emilia-Romagna, Italy. Two surge events are studied, one under conditions of bora wind (December 1995) and the other for a sirocco wind (November 1997). The model results are compared to hourly data from tide gauges in the northern Adriatic Sea. The three meteorological forcing fields produce storm surge elevations with generally similar behaviour but which differ from each other by up to 60 cm in height. The results obtained by using the UK Meteorological Office data were generally better than those obtained by using either of the two sets of meteorological model data. The model results give periods of 21.3, 11.6, 7.3 and 5.6 h for the Adriatic Sea seiches that are produced by the excitation of the fundamental longitudinal oscillation.

Regional seas are exceptionally vulnerable to climate change, yet are the most directly societally important regions of the marine environment. The combination of widely varying conditions of mixing, forcing, geography (coastline and bathymetry) and exposure to the open-ocean makes these seas subject to a wide range of physical processes that mediates how large scale climate change impacts on these seas' ecosystems. In this paper we explore these physical processes and their biophysical interactions, and the effects of atmospheric, oceanic and terrestrial change on them. Our aim is to elucidate the controlling dynamical processes and how these vary between and within regional seas. We focus on primary production and consider the potential climatic impacts: on long term changes in elemental budgets, on seasonal and mesoscale processes that control phytoplankton's exposure to light and nutrients, and briefly on direct temperature response. We draw examples from the MEECE FP7 project and five regional models systems using ECOSMO, POLCOMS-ERSEM and BIMS_ECO. These cover the Barents Sea, Black Sea, Baltic Sea, North Sea, Celtic Seas, and a region of the Northeast Atlantic, using a common global ocean-atmosphere model as forcing. We consider a common analysis approach, and a more detailed analysis of the POLCOMS-ERSEM model. 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. Instead, results show a highly heterogeneous picture of positive and negative change arising from the varying mixing and circulation conditions. Even in the two highly stratified, deep water seas (Black and Baltic Seas) the increase in stratification is not seen as a first order control on primary production. The approaches to downscaled experiment design and lessons learned from the MEECE project are also discussed.

1365-2486; Ocean warming can modify the ecophysiology and distribution of marine organisms, and relationships between species, with nonlinear interactions between ecosystem components potentially resulting in trophic amplification. Trophic amplification (or attenuation) describe the propagation of a hydroclimatic signal up the food web, causing magnification (or depression) of biomass values along one or more trophic pathways. We have employed 3-D coupled physical-biogeochemical models to explore ecosystem responses to climate change with a focus on trophic amplification. The response of phytoplankton and zooplankton to global climate-change projections, carried out with the IPSL Earth System Model by the end of the century, is analysed at global and regional basis, including European seas (NE Atlantic, Barents Sea, Baltic Sea, Black Sea, Bay of Biscay, Adriatic Sea, Aegean Sea) and the Eastern Boundary Upwelling System (Benguela). Results indicate that globally and in Atlantic Margin and North Sea, increased ocean stratification causes primary production and zooplankton biomass to decrease in response to a warming climate, whilst in the Barents, Baltic and Black Seas, primary production and zooplankton biomass increase. Projected warming characterised by an increase in sea surface temperature of 2.29 ± 0.05 ºC leads to a reduction in zooplankton and phytoplankton biomasses of 11% and 6%, respectively. This suggests negative amplification of climate driven modifications of trophic level biomass through bottom-up control, leading to a reduced capacity of oceans to regulate climate through the biological carbon pump. Simulations suggest negative amplification is the dominant response across 47% of the ocean surface and prevails in the tropical oceans; whilst positive trophic amplification prevails in the Arctic and Antarctic oceans. Trophic attenuation is projected in temperate seas. Uncertainties in ocean plankton projections, associated to the use of single global and regional models, imply the need for caution when extending these considerations into higher trophic levels. This article is protected by copyright. All rights reserved.

Axisymmetric high-Reynolds-number laminar flows are simulated numerically. In particular, we consider the formation and propagation of single vortex rings from a circular orifice in a plane boundary, and pairs of vortex rings from a circular annulus in a plane boundary. During formation, single rings grow within an essentially potential flow, as in the similarity theory of Pullin (1979). When released they are shown to propagate in an almost inviscid manner, as described by Saffman (1970). Pairs of vortex rings, formed at a circular annulus, have been studied by Weidman & Riley (1993), both experimentally and computationally. They conclude from their observations that the behaviour of the rings depends primarily upon two parameters, namely the impulse applied to the fluid, during ring formation, and the gap width of the annulus. The results we present in this paper confirm the dependence of the flow on these parameters.

In this paper we use two inviscid models to study the interactions between coaxial pairs of vortex rings. One model is based upon the thin-ring approximation, the other is based upon a contour-dynamics approach. Predictions from the two models are in good agreement with one another, and with earlier results obtained from numercal simulations of the Navier-Stokes equations at high Reynolds number

[1] Carbon budgets are simulated for the northwest European continental shelf and adjacent regions of the northeast Atlantic. Both physical and biological processes are evaluated, including exchanges between the water column and the atmosphere and sea bed. We use a multi-year simulation of a coupled 3D hydrodynamics-ecosystem model (POLCOMS-ERSEM) driven by realistic atmospheric data, ocean boundary conditions and freshwater inputs for 1989 to 2004. The northeast Atlantic (20°W to 13°E, 40°N to 65°N), including the European shelf, is found to be a net sink for atmospheric CO2. Biological processes exert a stronger control over pCO2than temperature, and hence have a stronger effect on the air-sea CO2 exchange. For the European shelf, carbon sources of rivers and the uptake of atmospheric CO2 are balanced by horizontal transport off shelf and there is little carbon burial. There is net transport of carbon onto the shelf in the top 180 m of the water column and off the shelf below that depth, with a net carbon loss of ∼6 ± 1 × 1012 mol C yr−1. Up to 50% of the carbon exported from the shelf is transported below the permanent pycnocline and so is isolated from release into the atmosphere on centennial timescales.

We examine the trends and variability in temperature of the northwest European shelf seas over the period 1960–2004 using four approaches: a regional model simulation (using the Proudman Oceanographic Laboratory Coastal Ocean Modelling System; POLCOMS), in situ multi-annual timeseries observations, satellite remote sensed (AVHRR) sea surface temperature (SST), and an analysis of data held in an international database at the International Council for the Exploration of the Sea (ICES). We focus on variability for the full period and trends from 1985 to 2004, being limited by the length of model simulation and the availability of satellite data. We find that all data sources give a consistent picture, with both trends and variability being intensified on-shelf and north of ∼48°N. The model and AVHRR SST show statistically significant warming trends in large areas of this region that are clearly distinguishable from both model/observation error and natural variability on these timescales. This ‘signal to noise ratio’ is substantially reduced when near bottom temperatures are considered in the model. The long timeseries at Port Erin (Isle of Man) shows that the variation in trend is well represented by the model and that the warming trend in the period 1985–2004 is substantially larger and of longer duration than previous peaks in 20-year trends since 1914. We find that the SST trends are greater in the model and satellite observations than the air temperature trends in the ERA40 re-analysis used for forcing; the net sea to air heat flux is ∼20% less in 1985–2004 than 1960–1984 (including shortwave, longwave, sensible and latent components). This is partly compensated by a ∼9% reduction in advective warming. The model shows the trends in seasonally stratified regions are greater at the surface than at depth, indicating an increase in this stratification. While this pattern is also seen in the annual trends from the ICES data analysis, the lack of seasonal resolution hampers a quantitative corroboration. The model is seen to have good skill in reproducing both the trends and variability, but tends to underestimate the trends. The modelled variability is overestimated in some coastal and open ocean regions and underestimated elsewhere, while the phase of this variability is generally well represented. Generally the model performance is better on-shelf than in the open ocean.

In this paper we clearly demonstrate that changes in oceanic nutrients are a first order factor in determining changes in the primary production of the northwest European continental shelf on time scales of 5–10 yr. We present a series of coupled hydrodynamic ecosystem modelling simulations, using the POLCOMS-ERSEM system. These are forced by both re-analysis data and a coupled ocean-atmosphere general circulation model (OA-GCM) representative of possible conditions in 2080–2100 under an SRES A1B emissions scenario, along with the corresponding present day control. The OA-GCM forced simulations show a substantial reduction in surface nutrients in the open-ocean regions of the model domain, comparing future and present day time-slices. This arises from a large increase in oceanic stratification. Tracer transport experiments identify a substantial fraction of on-shelf water originates from the open-ocean region in the south of the domain, where this increase is largest, and indeed the on-shelf nutrient and primary production are reduced as this water is transported on shelf. This relationship is confirmed quantitatively by comparing changes in winter nitrate with total annual nitrate uptake. The reduction in primary production by the reduced nutrient transport is mitigated by on-shelf processes relating to temperature, stratification (length of growing season) and recycling. Regions less exposed to ocean-shelf exchange in this model (Celtic Sea, Irish Sea, English Channel, and southern North Sea) show a modest increase in primary production (of 5–10 %) compared with a decrease of 0–20 % in the outer shelf, central and northern North Sea. These findings are backed up by a boundary condition perturbation experiment and a simple mixing model.

Annually integrated measurements of pCO(2) have demonstrated that seasonally stratified regions of temperate shelf seas can be an important sink of atmospheric CO2. A key process to support this sink is the transport of carbon from shelf seas to below the permanent pycnocline of the deep ocean. Using a hydrodynamic model simulation of the northwest European Continental shelf, we find that both the large scale circulation and frictional processes support the off-shelf transport of carbon sufficiently quickly to remove similar to 40% of the carbon sequestered by one growing season before the onset of the next. This transport is highly heterogeneous, with some regions being only weakly flushed. Only 52% of this exported carbon is transported below the permanent pycnocline, hence the shelf sea and open ocean carbon cycles are intrinsically coupled. Citation: Holt, J., S. Wakelin, and J. Huthnance (2009), Down-welling circulation of the northwest European continental shelf: A driving mechanism for the continental shelf carbon pump

We review mechanisms and studies of exchange between the north-east Atlantic and the adjacent shelf seas. Well-developed summer upwelling and associated filaments off Portugal and north-west Spain give exchange O(3 m2/s per unit length of shelf). Prevailing westerly winds further north drive exchange O(1 m2/s). Poleward flow along most of the upper slope has associated secondary circulation O(1 m2/s), meanders and eddies. Eddies are shed from slope waters into the Bay of Biscay, and local exchanges occur at shelf spurs and depressions or canyons (e.g. dense-water cascading of order 1 m2/s). Tidal transports are larger, but their reversal every six hours makes exchange largely ineffective except where internal tides are large and non-linear, as in the Celtic Sea where solitons carry water with exchange O(1 m2/s). These various physical exchanges amount to an estimated 2–3 m2/s per unit length of shelf, between ocean and shelf. A numerical model estimate is comparable: 2.5×106 m3/s onto and off the shelf from Brittany to Norway. Mixing controls the seasonal thermocline, affecting primary production and hence fluxes and fate of organic matter. Specifically, CO2 take-up by primary production, settling below the thermocline before respiration, and then off-shelf transport, make an effective shelf-sea "pump" (for CO2 from the atmosphere to the deep ocean). However, knowledge of biogeochemical fluxes is generally sparse, giving scope for more measurements, model validation and estimates from models.

Data from climatology (World Ocean Atlas) and two large scale operational ocean models (Forecasting Ocean Assimilation Model (FOAM), UK Met. Office and the Navy Coastal Ocean Model (NCOM), US Naval Research Laboratory) are used to give initial and open boundary conditions for a northeast Atlantic implementation of the Proudman Oceanographic Laboratory Coastal Ocean Model System (POLCOMS). We study the effects of using the different datasets on the temperature fields and the circulation. On the continental shelf, comparisons of POLCOMS output with Advanced Very High Resolution Radiometer sea surface temperature data suggest that the effect of using different ocean model initial and boundary conditions is small and that, after 15 months of model time, the impact of the different initial conditions is negligible. Stronger evidence of influence is seen in the deeper oceanic regions of the domain. Volume fluxes through sections governing flow into and out of the North Sea, through the Irish Sea and along the shelf edge show that the impact of the different boundary conditions is small on the shelf but significant elsewhere. These results are contrasted with the use of climatology to assess the value of these Global Ocean Data Assimilation Experiment ocean model products.