Topographic influence on Gulf Stream meandering

Abstract

This study investigates the influence of bottom topography on the development of instabilities in Gulf-Stream-like jets using a two-layer quasi-geostrophic model. The approach combines a linear stability analysis with nonlinear numerical simulations to examine the formation of baroclinic instabilities and coherent structures such as eddies. The linear analysis is conducted through a matrix eigenvalue problem, most with piece-wise constant potential vorticity, while the time evolution of the flow is explored using an Octave model. Various idealized forms of topography are used when the jet is running parallel to a transition from deep to shallow water or crossing a ridge/seamount chain. The analysis demonstrates how interactions between waves associated with the shallow and deep layers of the jet and the topography contribute to perturbation growth through horizontal shear, baroclinic, and mixed-form instabilities.