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 ρ in a system rotating with Coriolis parameters f occurs when ρ < u/f, where u is the characteristic flow speed of the current. Using an inviscid, reduced gravity model in the limit of ρ large compared to the current width, separation criteria are derived for various coastal currents of uniform potential vorticity. In this model, separation occurs when centrifugal forces at the cape raise the density interface bounding the current to the surface. For a current bounded on the offshore edge by a density front, the critical radius of curvature ρc is approximately that found in the laboratory. For a current bounded by a zero-velocity contour, the expression for ρc must be multiplied by a factor of W/R, where W is the upstream current width and R is the Rossby radius.