On the Effect of Planetary Rotation on Shear and Density Layers in Stratified Flows

Abstract

The effect of the Coriolis forces on the dynamics of shear and density layers in stratified flows is investigated, an effect that has not been taken into account in most previous studies of turbulence-mean field or wave-mean field interactions. For instance, recent studies have shown that shear and density layers can grow in the presence of turbulence in a strongly stratified fluid but the effect of planetary rotation was not taken into account. To address this problem, wave-mean flow interaction in a stratified fluid is here investigated in the presence of rotation using direct numerical simulation. The results show that the wave-mean flow interaction and the formation of layers is less intense when rotation is present because the horizontal mean motions are deviated by the Coriolis forces, which tends to reduce the distortion of the wave field, and thus the wave-induced fluxes of buoyancy and momentum. This effect appears even when the rotation rate is weak.