Recent and Ongoing Changes in the High-latitude Atlantic (ROCHA)

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The high latitude seas of the North Atlantic are currently experiencing major changes (ocean warming, declining ice cover and major increases in heat loss to the atmosphere) associated with man-made climate change. These seas, specifically the Labrador, Irminger and Nordic (LIN) Seas are the key northern sites for the global ocean circulation. In recent research, we developed a temperature dataset spanning 2004-2008 for the Labrador and Irminger Seas from Argo float and Marine Mammal-Borne Sensor (MMBS) data. Our analysis of this dataset revealed that estimates of ocean boundary current temperatures in widely used international datasets are too warm by up to 2 deg Centigrade. Identification of such warm biases is critical to both observation and model-based studies of climate change impacts in this region. In our earlier study, we were restricted to a small spatial domain and a limited time period ending in 2008. However, as a result of expansion of the Argo float programme, new availability of additional MMBS data and the inclusion for the first time of glider and ship based measurements, we are now in position to develop a new much-enhanced dataset. Specifically, we are now able to extend the spatial domain to include the Nordic Seas (thereby including all North Atlantic dense water formation regions) and the time period to 2003-2012 (allowing a full examination of key changes in the past decade). In addition, it is now possible to include salinity as well as temperature, thereby enabling new insights into changing freshwater content and ocean density. We propose to develop a world-leading new T and S dataset covering the Labrador, Irminger and Nordic Seas, which will be the first to employ all available observations across this region. Furthermore, we will use the new dataset to a.) determine recent and ongoing changes in the LIN Seas, and b.) critically evaluate the NEMO ocean model (NERCs flagship computer model of the ocean) and thus identify the extent to which it can be relied upon to provide further insights in this area. The proposed research is a major advance on our previous study and is vital as the LIN Seas are widely recognised to be a key indicator region for the early detection of climate change impacts.