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Ocean warm and saline Atlantic water (AW) flows northward towards the Arctic. This water crosses the Greenland‐Scotland Ridge in three inflow branches:  the Iceland branch,  the Faroe branch and  the Shetland branch. The first monitoring of these branches was obtained along standard hydrographic sections and in the 1990s these observations were complemented by – at that time the state‐of‐the‐art technology – Acoustic Doppler Current Profilers (ADCPs) that could measure ocean currents directly. For many years the ADCPs were the backbone in transport estimates of the inflowing AW, but in order to get reliable estimates, a high number of moorings were necessary which was costly both in consumables and man‐power. Alternative methods were therefore needed. The process to optimise the inflow arrays began several years ago by the integration of Satellite Altimetry data . Over the years, more data have been obtained at the inflow arrays, including new data types, and within Blue‐Action analyses have been performed utilizing the available data in order to optimise the monitoring of the inflow arrays both with respect to cost and in order to produce more accurate estimates of AW volume, heat and salt transports. Resulting from the work undertaken in Blue‐Action, the recommendations for future monitoring the three inflow branches are as follows: Iceland branch: Combined observations from one or two ADCP moorings (including hydrographicobservations at intermediate depth) and four annual hydrographic surveys. Faroe branch: Combined observations from satellite altimetry, one ADCP mooring, three PIES (Pressure Inverted Echo Sounders), one bottom temperature logger and at least three annual hydrographic surveys. Shetland branch: A combination of gridded geostrophic surface velocities from satellite altimetry, at least three annual hydrographic cruises along the section and continued ADCP deployments at key sites (such as in the Shetland slope current).

Presentations given by Blue-Action scientists at a stakeholder engagement event for Scotland, 16th October 2019 at Edinburgh City Chambers. For more information please see www.blue-action.eu, or contact the communications office at hannah.grist@srsl.com.

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.

This report presents results from an experiment, carried out in 2011-2012 within the EU-THOR project to investigate whether future monitoring of the Atlantic water transport through the Faroe-Shetland Channel might be more efficiently achieved on another section than the traditional Munken-Fair Isle section. The new section is less affected by meso-scale activity and narrower, allowing better horizontal resolution of the mooring array, but the experiment revealed that moving to the new section involved other drawbacks. The experiment also confirmed an earlier conjecture that data from satellite altimetry might provide better estimates of transport variations than estimates based on in situ measurements, solely. Previous efforts to determine the average volume transport of Atlantic water through the channel and its variations have been hampered by lack of information on the thickness variations of the Atlantic layer. Re-evaluating the historical data set, we find that the transport estimates are not significantly affected by assuming that the lower boundary of the Atlantic layer is fixed, equal to the average 5°C-isotherm. Based on the conclusions of this report, we recommend that future in situ monitoring in the channel is re-focused.

From 1994 to 2011, instruments measuring ocean currents (Acoustic Doppler Current Profilers; ADCPs) have been moored on a section crossing the Faroe–Shetland Channel. Together with CTD (Conductivity Temperature Depth) measurements from regular research vessel occupations, they describe the flow field and water mass structure in the channel. Here, we use these data to calculate the average volume transport and properties of the flow of warm water through the channel from the Atlantic towards the Arctic, termed the Atlantic inflow. We find the average volume transport of this flow to be 2.7 ± 0.5 Sv (1 Sv = 106 m3 s–1) between the shelf edge on the Faroe side and the 150 m isobath on the Shetland side. The average heat transport (relative to 0 °C) was estimated to be 107 ± 21 TW (1 TW = 1012 W) and the average salt import to be 98 ± 20 × 106 kg s−1. Transport values for individual months, based on the ADCP data, include a large level of variability, but can be used to calibrate sea level height data from satellite altimetry. In this way, a time series of volume transport has been generated back to the beginning of satellite altimetry in December 1992. The Atlantic inflow has a seasonal variation in volume transport that peaks around the turn of the year and has an amplitude of 0.7 Sv. The Atlantic inflow has become warmer and more saline since 1994, but no equivalent trend in volume transport was observed.

The Blue-Action team presented a webinar on 22nd October 2020 as part of Climateurope #ClimateThursday webinar series on climate services. The topic was "Ocean observations and predictions in response to the climate emergency", including presentations from Barbara Berx (Marine Scotland), Noel Keenlyside (University of Bergen) and Mark R. Payne (DTU).

Presentation by B. Berx to colleagues in Marine Scotland on recent climate change work. The topics covered include: an introduction of climate change, the work of the IPCC and UNFCCC, the current 6th Assessment Report cycle in IPCC and the most recent published report on the physical science basis. The presentation then moved on to include an overview of the role of the ocean in global climate and the importance of sustained ocean observations, the merit of historic records and the knowledge gained from some of Marine Scotland's own sustained ocean observations. Results from the Blue Action project were presented as part of how this knowledge then translates to important information for climate prediction on decadal time scales and how this can inform decision making processes, for example in the area of fisheries management.

Assessment of key lower latitude influences on the Arctic and their simulation Summary Blue-Action Work Package 2 (WP2) focuses on lower latitude drivers of Arctic change, with a focus on the influence of the Atlantic Ocean and atmosphere on the Arctic. In particular, warm water travels from the Atlantic, across the Greenland-Scotland ridge, through the Norwegian Sea towards the Arctic. A large proportion of the heat transported northwards by the ocean is released to the atmosphere and carried eastward towards Europe by the prevailing westerly winds. This is an important contribution to northwestern Europe's mild climate. The remaining heat travels north into the Arctic. Variations in the amount of heat transported into the Arctic will influence the long term climate of the Northern Hemisphere. Here we assess how well the state of the art coupled climate models estimate this northwards transport of heat in the ocean, and how the atmospheric heat transport varies with changes in the ocean heat transport. We seek to improve the ocean monitoring systems that are in place by introducing measurements from ocean gliders, Argo floats and satellites. These state of the art computer simulations are evaluated by comparison with key trans-Atlantic observations. In addition to the coupled models ‘ocean-only’ evaluations are made. In general the coupled model simulations have too much heat going into the Arctic region and the transports have too much variability. The models generally reproduce the variability of the Atlantic Meridional Ocean Circulation (AMOC) well. All models in this study have a too strong southwards transport of freshwater at 26°N in the North Atlantic, but the divergence between 26°N and Bering Straits is generally reproduced really well in all the models. Altimetry from satellites have been used to reconstruct the ocean circulation 26°N in the Atlantic, over the Greenland Scotland Ridge and alongside ship based observations along the GO-SHIP OVIDE Section. Although it is still a challenge to estimate the ocean circulation at 26°N without using the RAPID 26°N array, satellites can be used to reconstruct the longer term ocean signal. The OSNAP project measures the oceanic transport of heat across a section which stretches from Canada to the UK, via Greenland. The project has used ocean gliders to great success to measure the transport on the eastern side of the array. Every 10 days up to 4000 Argo floats measure temperature and salinity in the top 2000m of the ocean, away from ocean boundaries, and report back the measurements via satellite. These data are employed at 26°N in the Atlantic to enable the calculation of the heat and freshwater transports. As explained above, both ocean and atmosphere carry vast amounts of heat poleward in the Atlantic. In the long term average the Atlantic ocean releases large amounts of heat to the atmosphere between the subtropical and subpolar regions, heat which is then carried by the atmosphere to western Europe and the Arctic. On shorter timescales, interannual to decadal, the amounts of heat carried by ocean and atmosphere vary considerably. An important question is whether the total amount of heat transported, atmosphere plus ocean, remains roughly constant, whether significant amounts of heat are gained or lost from space and how the relative amount transported by the atmosphere and ocean change with time. This is an important distinction because the same amount of anomalous heat transport will have very different effects depending on whether it is transported by ocean or the atmosphere. For example the effects on Arctic sea ice will depend very much on whether the surface of the ice experiences anomalous warming by the atmosphere versus the base of the ice experiencing anomalous warming from the ocean. In Blue-Action we investigated the relationship between atmospheric and oceanic heat transports at key locations corresponding to the positions of observational arrays (RAPID at 26°N, OSNAP at ~55N, and the Denmark Strait, Iceland-Scotland Ridge and Davis Strait at ~67N) in a number of cutting edge high resolution coupled ocean-atmosphere simulations. We split the analysis into two different timescales, interannual to decadal (1-10 years) and multidecadal (greater than 10 years). In the 1-10 year case, the relationship between ocean and atmosphere transports is complex, but a robust result is that although there is little local correlation between oceanic and atmospheric heat transports, Correlations do occur at different latitudes. Thus increased oceanic heat transport at 26°N is accompanied by reduced heat transport at ~50N and a longitudinal shift in the location of atmospheric flow of heat into the Arctic. Conversely, on longer timescales, there appears to be a much stronger local compensation between oceanic and atmospheric heat transport i.e. Bjerknes compensation.

The Arctic is warming twice as fast as anywhere else on the planet and rapid changes are occurring, from sea ice melt to warming air temperatures. However, these impacts are not restricted to the far north, as the Arctic is connected to the rest of the world via the atmospheric and ocean circulations. Understanding the drivers of these changes, and the connections between the Arctic and the Northern Hemisphere, allows us to make predictions about the impact beyond the Arctic. Developing robust predictions is a vital step to allow businesses, communities and government to be able to adapt to the future. Blue-Action is building blocks of ocean observations and computer models to co-design tools that enable stakeholders to act on climate change.&nbsp

Presentation by B. Berx to colleagues in Marine Scotland on recent climate change work. The topics covered include: an introduction of climate change, the work of the IPCC and UNFCCC, the current 6th Assessment Report cycle in IPCC and the most recent published report on the physical science basis. The presentation then moved on to include an overview of the role of the ocean in global climate and the importance of sustained ocean observations, the merit of historic records and the knowledge gained from some of Marine Scotland's own sustained ocean observations. Results from the Blue Action project were presented as part of how this knowledge then translates to important information for climate prediction on decadal time scales and how this can inform decision making processes, for example in the area of fisheries management.

Ocean warm and saline Atlantic water (AW) flows northward towards the Arctic. This water crosses the Greenland‐Scotland Ridge in three inflow branches:  the Iceland branch,  the Faroe branch and  the Shetland branch. The first monitoring of these branches was obtained along standard hydrographic sections and in the 1990s these observations were complemented by – at that time the state‐of‐the‐art technology – Acoustic Doppler Current Profilers (ADCPs) that could measure ocean currents directly. For many years the ADCPs were the backbone in transport estimates of the inflowing AW, but in order to get reliable estimates, a high number of moorings were necessary which was costly both in consumables and man‐power. Alternative methods were therefore needed. The process to optimise the inflow arrays began several years ago by the integration of Satellite Altimetry data . Over the years, more data have been obtained at the inflow arrays, including new data types, and within Blue‐Action analyses have been performed utilizing the available data in order to optimise the monitoring of the inflow arrays both with respect to cost and in order to produce more accurate estimates of AW volume, heat and salt transports. Resulting from the work undertaken in Blue‐Action, the recommendations for future monitoring the three inflow branches are as follows: Iceland branch: Combined observations from one or two ADCP moorings (including hydrographicobservations at intermediate depth) and four annual hydrographic surveys. Faroe branch: Combined observations from satellite altimetry, one ADCP mooring, three PIES (Pressure Inverted Echo Sounders), one bottom temperature logger and at least three annual hydrographic surveys. Shetland branch: A combination of gridded geostrophic surface velocities from satellite altimetry, at least three annual hydrographic cruises along the section and continued ADCP deployments at key sites (such as in the Shetland slope current)., The Blue-Action project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 727852

The Arctic is warming twice as fast as anywhere else on the planet and rapid changes are occurring, from sea ice melt to warming air temperatures. However, these impacts are not restricted to the far north, as the Arctic is connected to the rest of the world via the atmospheric and ocean circulations. Understanding the drivers of these changes, and the connections between the Arctic and the Northern Hemisphere, allows us to make predictions about the impact beyond the Arctic. Developing robust predictions is a vital step to allow businesses, communities and government to be able to adapt to the future. Blue-Action is building blocks of ocean observations and computer models to co-design tools that enable stakeholders to act on climate change.&nbsp

The Arctic is warming twice as fast as anywhere else on the planet and rapid changes are occurring, from sea ice melt to warming air temperatures. However, these impacts are not restricted to the far north, as the Arctic is connected to the rest of the world via the atmospheric and ocean circulations. Understanding the drivers of these changes, and the connections between the Arctic and the Northern Hemisphere, allows us to make predictions about the impact beyond the Arctic. Developing robust predictions is a vital step to allow businesses, communities and government to be able to adapt to the future. Blue-Action is building blocks of ocean observations and computer models to co-design tools that enable stakeholders to act on climate change., The Blue-Action project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 727852.

Assessment of key lower latitude influences on the Arctic and their simulation Summary Blue-Action Work Package 2 (WP2) focuses on lower latitude drivers of Arctic change, with a focus on the influence of the Atlantic Ocean and atmosphere on the Arctic. In particular, warm water travels from the Atlantic, across the Greenland-Scotland ridge, through the Norwegian Sea towards the Arctic. A large proportion of the heat transported northwards by the ocean is released to the atmosphere and carried eastward towards Europe by the prevailing westerly winds. This is an important contribution to northwestern Europe's mild climate. The remaining heat travels north into the Arctic. Variations in the amount of heat transported into the Arctic will influence the long term climate of the Northern Hemisphere. Here we assess how well the state of the art coupled climate models estimate this northwards transport of heat in the ocean, and how the atmospheric heat transport varies with changes in the ocean heat transport. We seek to improve the ocean monitoring systems that are in place by introducing measurements from ocean gliders, Argo floats and satellites. These state of the art computer simulations are evaluated by comparison with key trans-Atlantic observations. In addition to the coupled models ‘ocean-only’ evaluations are made. In general the coupled model simulations have too much heat going into the Arctic region and the transports have too much variability. The models generally reproduce the variability of the Atlantic Meridional Ocean Circulation (AMOC) well. All models in this study have a too strong southwards transport of freshwater at 26°N in the North Atlantic, but the divergence between 26°N and Bering Straits is generally reproduced really well in all the models. Altimetry from satellites have been used to reconstruct the ocean circulation 26°N in the Atlantic, over the Greenland Scotland Ridge and alongside ship based observations along the GO-SHIP OVIDE Section. Although it is still a challenge to estimate the ocean circulation at 26°N without using the RAPID 26°N array, satellites can be used to reconstruct the longer term ocean signal. The OSNAP project measures the oceanic transport of heat across a section which stretches from Canada to the UK, via Greenland. The project has used ocean gliders to great success to measure the transport on the eastern side of the array. Every 10 days up to 4000 Argo floats measure temperature and salinity in the top 2000m of the ocean, away from ocean boundaries, and report back the measurements via satellite. These data are employed at 26°N in the Atlantic to enable the calculation of the heat and freshwater transports. As explained above, both ocean and atmosphere carry vast amounts of heat poleward in the Atlantic. In the long term average the Atlantic ocean releases large amounts of heat to the atmosphere between the subtropical and subpolar regions, heat which is then carried by the atmosphere to western Europe and the Arctic. On shorter timescales, interannual to decadal, the amounts of heat carried by ocean and atmosphere vary considerably. An important question is whether the total amount of heat transported, atmosphere plus ocean, remains roughly constant, whether significant amounts of heat are gained or lost from space and how the relative amount transported by the atmosphere and ocean change with time. This is an important distinction because the same amount of anomalous heat transport will have very different effects depending on whether it is transported by ocean or the atmosphere. For example the effects on Arctic sea ice will depend very much on whether the surface of the ice experiences anomalous warming by the atmosphere versus the base of the ice experiencing anomalous warming from the ocean. In Blue-Action we investigated the relationship between atmospheric and oceanic heat transports at key locations corresponding to the positions of observational arrays (RAPID at 26°N, OSNAP at ~55N, and the Denmark Strait, Iceland-Scotland Ridge and Davis Strait at ~67N) in a number of cutting edge high resolution coupled ocean-atmosphere simulations. We split the analysis into two different timescales, interannual to decadal (1-10 years) and multidecadal (greater than 10 years). In the 1-10 year case, the relationship between ocean and atmosphere transports is complex, but a robust result is that although there is little local correlation between oceanic and atmospheric heat transports, Correlations do occur at different latitudes. Thus increased oceanic heat transport at 26°N is accompanied by reduced heat transport at ~50N and a longitudinal shift in the location of atmospheric flow of heat into the Arctic. Conversely, on longer timescales, there appears to be a much stronger local compensation between oceanic and atmospheric heat transport i.e. Bjerknes compensation., The Blue-Action project has received funding from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement No 727852.

Warm and saline water of Atlantic origin is transported across the Greenland Scotland Ridge into the Arctic Mediterranean. This inflow has a large impact on e.g. the climate and sea-ice in the Arctic and the knowledge of its variability and possible trend is therefore of huge importance in predicting Arctic climate change. The inflow has been monitored since the late 1990s with moored instrumentation combined with regular hydrographic cruises and data from satellite altimetry, but deploying moorings in the heavily fished region close to the Greenland Scotland Ridge is highly demanding in terms of manpower and funding. Efforts have therefore been made to optimize the monitoring systems, lately within the H2020 Blue-Action project. This has led to systems, which rely heavily on satellite altimetry. More recently moored PIES (Pressure Inverted Echo Sounders) have been used in a pilot project to monitor short-term variations of the temperature and salinity fields and these results look promising.