Eddy formation in the Denmark Strait overflow

Abstract

On the basis of observations along the continental slope of east Greenland, a primitive equation, open boundary model is used to study the formation of eddies in the Denmark Strait overflow. The eddies are produced by vortex tube stretching, initiated by cross‐slope components of the velocity field. A sequence of cyclones and anticyclones is formed; the cyclones are located along the deeper part of the slope, and the anticyclones are along the shallower slope. The eddies are almost barotropic with horizontal and vertical velocities of 30 cm s−1 and 0.1 cm s−1, respectively. The cyclones migrate along the isobaths with a slight downhill component and intensify on their path until they become influenced by the flat, deep basin. Their translation speed is typically 20–30 cm s−1, and the local change in relative vorticity is nearly entirely determined by vortex tube stretching and vorticity advection. The overflow water flows mainly between the cyclonic and anticyclonic eddy chains. The overflow is strongly accelerated by the eddies. The existence of anticyclonic eddies along the shallower part of the east Greenland continental slope, predicted by the numerical model, has been confirmed by observations.