Generation of Topographic Waves over the Continental Margin

Abstract

Numerical experiments were carried out to simulate the generation of topographic waves by a Gulf Stream ring over the continental margin in a stratified ocean on an f-plane. The study was aimed at understanding the combined effect of density advection and bottom topography on the flow field. The momentum equation is linear, and nonlinearity is introduced in the density equation. The mechanism of wave generation was investigated by turning on and off the nonlinear density advection and by changing the strength of the ring and bottom topography. The results show that topographic waves are generated by advection of density in a ring over a sloping bottom. The vorticity associated with the swirl velocity of a ring is less important during wave generation. The strength of a ring affects the wave amplitude; in the case of a strong ring, self-advection of density may be induced at the surface. However, the generation and propagation of topographic waves are independent of the strength of the ring. Waves of the observed amplitude can be generated by this process over the continental slope and upper rise of the Mid-Atlantic Bight.