A numerical study of stratified tidal rectification

At the top of the continental slope, the barotropic tide provides a forcing for internal tide generation and topographic rectification. Both of these phenomena exhibit non-linear features such as Eulerian residual currents, which are the main topic of this paper. Those currents are studied with the numerical model MICOM, validated on the basis of a previous theoretical study and operated without bottom friction nor density mixing. We then proceed to the realistic case of the seasonal thermocline above the continental slope, thereby extending numerically the scope of the existing theories. The main effect of the density stratification is to intensify the topographically rectified current in the lower part of the water column, thereby diminishing the surface residual current. The numerical simulations show that the surface residual current can be expected to go from zero at the end of summer to its maximum (barotropic) value during winter, owing to the annual cycle of stratification in the upper layers of the ocean.