On the influence of stratification and continental shelf and slope topography on the dispersion of subinertial coastally trapped waves

Abstract

The behavior of subinertial, coastally trapped free waves in a continuously stratified ocean is examined using a two-slope topography in which the continental shelf and slope are each represented by a single uniform slope. Surface-intensified stratification is assumed in which the squared buoyancy frequency profile is of the form N2eβz, where N is the buoyancy frequency at the surface (z = 0) and β the vertical decay scale normalized by the deep-sea depth. The continental slope is typically assumed to be steeper than the shelf. Two qualitatively different types of dispersive behavior are distinguished. When (N/f)a2 > eβh/2, where f is the Coriolis parameter, a2 the bottom slope of the continental slope, and h the shelf-break depth normalized by the deep-sea depth, then free waves may occur at any subinertial frequency, and each dispersion curve rises to f at some finite alongshore wavenumber (as in the case of baroclinic Kelvin waves). If (N/f)a2