Viscid Eastern Boundary Dynamics and the Spreading of Mediterranean Water along the Portuguese Continental Slope

Abstract

A linear, continuously stratified model is used to investigate the flows generated by a midlatitude, eastern boundary zonal inflow representing the flux of Mediterranean Water into the North Atlantic. The model allows for time dependence and vertical mixing of density and meridional momentum and assumes a geostrophic balance for zonal momentum. Rossby and Kelvin wave propagation and dissipation away from the inflow region determine the character of the analytical solutions. For both periodic and steady forcing and for a wide range of mixing coefficients, currents have a significant boundary signature. Inflows generate poleward currents at the depth of the forcing and weaker countercurrents above and below. The amplitude of meridional coastal flows can be substantially larger than the amplitudes of the forcing jet, and interior flows are generally weaker. Zonal decay scales depend on the amount of mixing and the relative importance of Kelvin and Rossby wave dynamics in the solutions.