The influence of layer outcropping on the separation of boundary currents. Part II: The wind- and buoyancy-driven experiments

It is shown that the main characteristic of the Parsons western boundary current separation mechanism, namely a separation south of the zero wind stress curl line (ZWCL), is no longer present when diabatic effects are included through the addition of a mixed layer to the model structure. When diabatic processes are taken into account, the separation is associated with the outcropping of interior layers into the mixed layer where the horizontal density gradient is a maximum. The maintenance of this maximum results from a balance between potential vorticity conservation and diabatic processes. In spite of wide variations in either forcing functions or parameters, the flow patterns of the thermally forced experiments described herein remain very similar from one experiment to the other, with a separation latitude located at the ZWCL. It is only when salinity is allowed to vary significantly in space that one observes a significant move in the jet separation latitude.