Instability of a shelfbreak front

Abstract

In an attempt to understand whether local instabilities can account for the observed frontal variability in the Middle Atlantic Bight, a linear stability analysis was conducted for a wide range of background density and velocity fields. Three-dimensional perturbations superposed on a continuously stratified shelfbreak front were investigated using the hydrostatic primitive equations. Model results indicate that the shelfbreak frontal jet is unstable over the wide parameter range dictated by the observed velocity and density structure. Model growth rates, on the order of one day, and wavelengths of ~10-50 km compare favorably to observations, suggesting that local baroclinic/barotropic instabilities are a likely source for the strong temporal and spatial variability of the shelfbreak front in the Middle Atlantic Bight.