EDDY JET INTERACTION THEOREMS FOR PIECEWISE-CONSTANT POTENTIAL VORTICITY FLOWS

Integral constraints governing interactions between jets and detached eddies are discussed for quasigeostrophic flows with piecewise uniform potential vorticity. Building on the work of Dritschel (Journal of Fl uid Mechanics, 191: 575-581 (1988b)), we use conservation of pseudomom entum to predict the propagation direction of eddies (closed fronts) o r place bounds on their excursions. The piecewise uniform condition al so allows for a simple interpretation of a well-known eddy-mean flow i nteraction theorem. Specifically, it is shown that mean zonal velocity is equal to its undisturbed value plus a weighted sum of displaced ar eas (or volumes) under fronts which have crossed the latitude line in question. All results are valid regardless of the amplitude or shape o f frontal disturbances.