Structure of jets in rotating systems

Abstract

An investigation of the structure of jets in rotating systems is presented. The fluid is assumed to be homogeneous and the flow laminar and quasi-geostrophic. When the rate of rotation is small, the dynamics is shown to be identical to that of jets in non-rotating systems, being a balance between inertial terms and lateral dissipation. As the rate of rotation increases the Ekman layers become important and in the strongly rotating case the friction in the Ekman layers dominates lateral dissipation. The jet in a non-rotating system entrains fluid at its edges and the downstream momentum flux is independent of the distance downstream. In the strongly rotating case, however, the jet ejects fluid at its edges and the downstream momentum flux decreases with downstream distance due to dissipation in the Ekman layers. A similarity solution for the general case with both types of friction is obtained and the transition from a jet in which lateral dissipation dominates to one in which Ekman friction is more important is discussed. General features of jets in strongly rotating systems are studied and implications for the Gulf Stream are mentioned.