The effect of continental slope on buoyancy-driven circulation

The effect of continental slope on buoyancy-driven circulation has been stu died using a two-layer quasigeostrophic model. In the model, buoyancy flux is incorporated as interfacial mass flux, which consists of narrow intense detrainment in the north and broad entrainment in the south. The model expl icitly shows that, in the presence of the continental slope, a small amount of buoyancy flux can drive a strong barotropic flow. This flow develops be cause the beta effect of bottom topography either reduces or deflects the b uoyancy-driven deep flow so that it cannot compensate its overlying counter flow, thus generating a net transport. As a result, in a double gyre circul ation with a western continental slope, a small amount of detrainment/entra inment water mass can substantially enhance the transport of the western bo undary current through southwestern deflection of the deep subpolar circula tion. For example, with a reasonable western continental slope, a 10 Sv (Sv equivalent to 10(6) m(3) s(-1)) detrainment mass flux can increase the tra nsport of the western boundary current from 40 Sv of the wind-driven transp ort to 148 Sv. Relevance to the North Atlantic is then discussed.