Does Atmospheric Cooling Drive the Gulf Stream Recirculation?

Abstract

Abstract A two-layer model for the recirculation is studied Initially, a narrow jet of the upper layer moves eastward with the lower layer remaining stagnant. Att = 0 cold air flows over the narrow front region, all the moving water in the upper layer sinks to the lower layer with the momentum vertically well mixed within the lower layer. Thus, cooling creates an unbalanced eastward jet in the second layer and an unbalanced pressure field at a vertical density front. After the geostrophic adjustment a high pressure center south of the front and a low pressure center north of the front are established. These pressure centers drive a much stronger barotropic eastward current slightly north of the pressure center and slow westward return flow in the far field both south and north of the front. Thus, cooling over a narrow stream can intensify an eastward jet and create recirculation gyres both north and south of the stream.