Evolution of baroclinic planetary eddies over localized bottom topography in terms of JEBAR

Abstract

Numerical experiments have been conducted to investigate the evolution of pure baroclinic eddies using two-layer planetary geostrophic equations in the presence of localized bottom topography. In particular, we interpret the eddy motion in terms of JEBAR (joint effect of baroclinicity and relief). It is shown that the emission of barotropic flows (or waves), westward acceleration and energy conversion occur when an eddy interacts with bottom topography. A meridional ridge acts as a repellor for a cold eddy and an attractor for warm eddy due to JEBAR-induced barotropic flows (or waves), which is consistent with the vorticity argument. This mechanism may provide a possible explanation not only for the global distribution of the phase speed of baroclinic Rossby waves observed in the Pacific by the TOPEX/POSEIDON satellite altimeter but also for the abrupt change in the trajectories of the westward propagating baroclinic eddies observed in the North Atlantic.