On steady quasi-geostrophic flow component formation over undulating bottom topography: PART II. a two-layer low-order model of the open ocean

Abstract

Abstract An equilibrium quasi-linear regime consisting of forced topographic waves and a steady flow component correlated with bottom relief is analysed using the low-order spectral model of quasi-geostrophic ocean dynamics. Two functions - a correlation C between potential vorticity and the topography and a topographic stress force D - are employed to study the qualitative structure of the steady flow component. Both a negative and positive C appear in the model. This function is denned mostly by topographically induced energy fluxes among barotropic and/or among baroclinic modes when the horizontal scale of the bottom undulations is smaller than the internal Rossbi radius. Over the large-scale topographic features, the interface displacements, controlled by the energy transfer between barotropic and baroclinic components, dominate in C. The β-effect tries to develop negative homogeneous C. D is derected oppositively to the phase velocity of the incident wave for motions on an f-plane. The β-effect induc...