Exchange between the Slope Current and the West Shetland Shelf

Since 1994, mooring deployments on the West Shetland Shelf and in the Faroe-Shetland Channel (FSC) have monitored the strength of the North West European Slope Current north of the Wyville Thomson Ridge, as part of a transport mooring array (TMA) observing the strength of Atlantic transport to the Nordic Seas. Between 2013 and 2015, several surface drifters (1m drogued) were also released to study exchange of the slope current with the coastal region around the Orkney and Shetland Islands. Analysis of the TMA observations to date has focused on quantifying the transport of water masses originating from the Atlantic Basin in general. The FASTNEt (Fluxes Across Sloping Topography of the North East Atlantic) project aims to study the ocean-shelf exchange, and in particular, the seasonal, inter-annual and regional variation around the North-West European continental shelf. As part of this project, the existing historic dataset is also being re-examined, and will be the focus of the work presented here. We will present an overview of the data collected in the FSC since October 1994, and discuss the seasonal and inter-annual variability of along-slope and cross-slope transport estimates based on the moored profiling current meters. The coincident time series of satellite altimetry further provides spatial context to the point-measurements from current meters in the FSC. The drifter deployments will also provide a Lagrangian context to the cross-shelf exchange in the region. As exploration for oil & gas continues to develop in the FSC, it will be key to continue elucidating the processes governing its circulation, and, in particular, the potential on-shelf transfer of hazardous substances.