On the Stability of Spatially Irregular Coastal Flows, with Application to the Florida Current

Abstract

A study is made of the propagation of continental shelf waves and barotropic Rossby waves in a steady, laterally sheared current of the form V + ?W, where ? ? 1 and W is a centered random function representing small-scale irregularities in the basic flow. If the correlation length of W is small compared with the characteristic horizontal length scale of the system (e.g., the shelf width) the waves are unstable. Their growth rate is largely determined by the correlation length and the amplitude of the fluctuating current, while the phase speed is given by the sum of weighted averages of the mean current V and the lateral gradient of potential vorticity. Application of the theory to the Brooks and Mooers (1977a) model of the Florida Current yields wave parameters that are in accord with those measured by Düing (1975).