Current broadening as a mechanism for anticyclogenesis at the Northwest Corner of the North Atlantic Current

Abstract

[1] The warm North Atlantic Current, flowing north just east of the Grand Banks, makes an abrupt turn to the east near 51°N. As the waters flow through this region, known as the Northwest Corner, the current broadens and weakens, effectively splitting into two zonal yet variable flows forming what is generally known as the Subpolar Front. The Northwest Corner also has the curious property that it expands and expels anticyclonic vortices on a quasi-regular basis, approximately every 2-1/2 months. Using an energy budget approach we show that this anticyclogenesis can be accounted for in terms of a kinetic energy convergence due to the broadening of the flow as it passes through the region. The principal export route for the newly formed eddies appears to be density-driven subduction, i.e. sinking, driven by severe heat-loss due to the exposed position of these warm waters in the southern Labrador Sea.