Ventilating Beta Plane Leases

Abstract

The theory of warm water lenses on beta planes is extended to include heat exchange between the lenses and their environment. The motivation for this study comes from recent observations of Gulf Stream warm core rings, which clearly show that warm rings are strongly modified by diabatic processes. Scaling arguments suggest that the effects of cooling on rings are comparable in magnitude to the effects of beta during much of the winter. The principal effect of beta on adiabatic lenses is to cause them to drift west. The addition of weak cooling causes the magnitude of the westward drift to decrease at a rate proportional to net heat loss. It is argued that typical cooling rates of warm core Gulf Stream rings can reduce their beta-driven motion by 20% during the course of a winter. While nontrivial, this effect is probably unmeasurable. The corrections to the dominantly radially symmetric field, which are induced by beta and modified by cooling, are also computed. These fields are time-dependent but evolve in relatively simple ways.