Effects of buoyancy flux on continental shelf circulation

Abstract

The effects of buoyancy flux at the surface of a two-dimensional, steady state, continuously stratified continental shelf have been considered. Similarity solutions have been generated using an interative technique. The solutions incorporate the influences of mechanical wind forcing, eddy diffusion, surface buoyancy flux and bottom topography. The traverse circulation can be decomposed into modes associated with the surface wind stress and the surface buoyancy flux and modified by stratification, mixing and bottom topography. For the special cases of a wind stress with zero curl or for zero wind stress, upwelling circulations can be induced by both the sloping bottom and by gravitational convective effects. Alongshore interior currents counter to the direction of the wind are observed and are attributed to baroclinic pressure gradients. The nature of the transverse and alongshore flows are characterized in terms of dimensionless ratios of: Coriolis to frictional forces, buoyancy to frictional forces; convective to diffusive forces; and horizontal to vertical mixing time scales and length scales.