IMPACT OF WIND FORCING, BOTTOM TOPOGRAPHY, AND INERTIA ON MIDLATITUDEJET SEPARATION IN A QUASI-GEOSTROPHIC MODEL

The persistence of unrealistic Gulf Stream separation in numerical mod els of the ocean has prompted many theories about possible mechanisms that influence the separation of a western boundary current from the c oast. In this paper. the joint effects of (a) coastline orientation, ( b) bottom topography, and (c) inertia on the midlatitude jet separatio n are explored in a wind-driven two-layer quasigeostrophic model. It i s shown that topographic effects are of importance in high eddy activi ty regions and that eddy-topography interactions strongly influence th e separation process. In order for the western boundary current to sep arate from the coastline and cross the f/h contours associated with th e continental rise, eddy fluctuations need to be weak at the separatio n point. This can be achieved either by introducing a positive wind st ress curl in the northern part of the domain or by increasing the iner tia of the western boundary current. In both cases, the separation is facilitated by low eddy activity, resulting in a decoupling of the upp er layer front the lower layer when the current crosses the f/h contou rs.