Presenter: Astrid Pacini (Woods Hole Oceanographic Institution)

Description:
The role of wind forcing on the dynamics of the West Greenland Coastal Current (WGCC) is analyzed using data from a high-resolution mooring array deployed between 2014-2018 near Cape Farewell, Greenland. The data are part of the Overturning of the Subpolar North Atlantic Program (OSNAP). The coastal current is an important source of freshwater to the subpolar North Atlantic, as it transports Arctic-origin and Greenland meltwaters cyclonically around the Labrador Sea. The ability for this freshwater to penetrate into the interior has important consequences for dense water formation and the lower limb of the Atlantic Meridional Overturning Circulation. However, the processes by which these freshwaters are fluxed offshore remain an open question. In this study, we identify all major upwelling events over the four-year record and diagnose the atmospheric drivers of these events. Strong storms known as tip jets, reverse tip jets, and barrier winds, are shown to have a direct influence on the isopycnal and velocity structure of the WGCC with lag times of 6-24 hours. The enhanced along-coast northeasterly winds trigger upwelling and drive a cross-stream Ekman cell. These circulation patterns flux freshwaters offshore at the surface and warm, salty, Atlantic-origin waters onshore at depth. The onshore flux of warm water onto the shelf could have important implications for glacial fjord temperatures and thus the release of increased freshwater into the coastal current. As winds in the region are upwelling-favorable in the mean, we diagnose how strong a wind event must be to generate a cross-stream flux of properties, and characterize how the events spin down.