On the decay of a baroclinic jet flowing along a continental slope

Abstract. A jet flowing in the Kelvin wave propagation direction along the seaward side of a continental slope is found to decrease in strength as it leaks mass onto the continental shelf. As a result, a shelf break jet flowing in the opposite direction is induced on the shelf. The combination of these two flows creates a decaying, high-pressure tongue centered about the shelf break. An idealized, reduced gravity model is developed to examine the two-flow combination. In the model a baroclinic open ocean jet flows next to a continental shelf over which the flow is barotropic and dominated by a linear bottom friction proportional to along-shelf velocity. The far-field depth of the thermocline is assumed to be much greater than the depth of the shelf break. A solution is found in the limit of small cross-slope flow. The mathematical problem of finding the flow on the shelf is equivalent to that of heat conduction on a semi-infinite rod with a finite heat source placed at the end of the rod. A numerical shelf/slope junction model is devised to allow the requirement of small cross-slope flow to be relaxed. The numerical model, which incorporates higher-order dynamics, confirms the qualitative results obtained from the analytic model. The motivation for the development of the theory lies in observational evidence of a northward flowing jet along the continental slope off the West Florida Shelf, apparently stemming from the Loop Current. The structure of the flow combination over the shelf break is confirmed with historical hydrographic data and advanced very high resolution radiometer imagery. 1