The Effects of Flow Asymmetry on the Direction of Rossby Wave Breaking

Abstract

The relationship between the direction of the breaking of Rossby waves on an isolated jet and the cross-jet asymmetry of the flow is investigated. The flow structure of a circular jet is, under most circumstances, such that waves break uniquely outward, although the authors contrive a flow on which breaking is uniquely inward. The influence on the direction of the breaking of the location of critical lines in the undisturbed flow is discussed. On a straight jet with asymmetric shear, there are three wave amplitude regimes: weak waves do not break; waves of moderate amplitude break only toward the closer critical line; and waves of sufficiently large amplitude break both ways.