Wednesday 29 March 2017 - 15:00
NOC Southampton - Henry Charnock Lecture Theatre (Waterfront Campus).
Large-scale forcing of the European Slope Current and associated inflows to the North Sea
The monitoring programmes RAPID and OSNAP are providing unprecedented information on the evolving large-scale ocean circulation. These and other observations may help us to better understand and predict the wider impacts of changes in the state and circulation of the North Atlantic. Here, large-scale oceanic changes are found to force responses at the eastern boundary, where the flow is constrained to closely follow isobaths as the European Slope Current. Some associated shelf edge exchange is important for UK shelf seas, and the North Sea in particular. Northward increases of density in the upper ~1000 m drive a broad eastward geostrophic flow, small fractions of which sustain the Slope Current. Changes in the density gradient drive corresponding changes in Slope Current transport and the North Sea influence, with a major decline around 1997 linked to sudden warming of the subpolar gyre at that time. Reinvigoration of the southern portion of the Slope Current is anticipated to follow dramatic cooling of the subpolar gyre over 2014-15. These changes are examined with eddy-resolving ORCA12 model hindcasts and a variety of observations. Likely consequences for shelf edge ecosystems and neighbouring shelf seas are considered.