INVISCID CURRENT SEPARATION FROM ROUNDED CAPES

Laboratory experiments have suggested that the separation of a coastal surface current from a cape of radius of curvature rho in a system ro tating with Coriolis parameter f occurs when rho < u/f where u is the characteristic flow speed of the current. Using an inviscid, reduced g ravity model in the limit of rho large compared to the current width, separation criteria are derived for various coastal currents of unifor m potential vorticity. In this model, separation occurs when centrifug al forces at the cape raise the density interface bounding the current to the surface. For a current bounded on the offshore edge by a densi ty front, the critical radius of curvature rho(c) is approximately tha t found in the laboratory. For a current bounded by a zero-velocity co ntour, the expression for rho(c) must be multiplied by a factor of W/R , where W is the upstream current width and R is the Rossby radius.