The Influence of Stratification on the Instabilities in an Idealized Two-Layer Ocean Model

Abstract

his work investigates the instability of a two-layer Bickley jet in the context of the rotating shallow water (RSW) model. This provides a general context in which the instability of oceanographic jets with simple stratification can be investigated. The three objectives of this work are as follows: First, the study investigates the morphology of unstable modes that can occur in this two-layer model. This is done by performing a linear stability analysis to investigate different types of flows both with and without vertical shear. Second, the authors study how the growth rates of the unstable modes are affected by changes in the stratification. Third, this study looks at the nonlinear evolution of some of these instabilities to determine how easy it is for nonprimary instabilities to develop. This is motivated by the fact that in the literature there have been many investigations that have found a multitude of unstable modes in this model, and it is not evident as to how easily they can be generated in oceanographic flows.