On the Separation of a Barotropic Western Boundary Current from a Cape

Abstract

The problem of western boundary current separation is investigated using a barotropic vorticity model. Specifically, a boundary current flowing poleward along a boundary containing a cape is considered. The meridional gradient of the Coriolis parameter (the ? effect), the strength of dissipation, and the geometry of the cape are varied. It is found that 1) all instances of flow separation are coincident with the presence of a flow deceleration, 2) an increase in the strength of the ? effect is able to suppress flow separation, and 3) increasing coastline curvature can overcome the suppressive ? effect and induce separation. These results are supported by integrated vorticity budgets, which attribute the acceleration of the boundary current to the ? effect and changes in flow curvature. The transition to unsteady final model states is found to have no effect upon the qualitative nature of these conclusions.