A Modal Analysis of Coastally Trapped Waves Generated by Tropical Cyclones

Abstract

The authors use numerical simulations of the shallow-water equations to study the generation of coastally trapped waves by localized forcing mechanisms. The model parameters are chosen to be typical for coastal ocean situations. The waves are generated by various wind-stress forcing mechanisms typical of atmospheric fronts or tropical cyclones that travel either parallel or normal to the coast, or in a combination of both of these. Coastally trapped waves fall into three classes: superinertial edge waves, Kelvin waves, and subinertial shelf waves. Mode-fitting routines are described, which when applied to the model output enable one to identify the type and modal properties of the waves generated. The authors' results show that for the typical wind stress forcing considered here, the generated wave field is dominated by low-mode shelf waves.