Convection In A Rotating Fluid Over A Sloping Bottom, With Application To The Arabian Gulf

Abstract

Convective motions over a sloping bottom driven by evaporation and freshening are investigated by integrating the complete momentum and mass conservation equations. The problem is posed as an initial value problem in a rotating frame of reference to study the dynamics of establishment of the quasi-steady state circulation when the rate of increase of density due to evaporation is equal to the rate of decrease of density due to freshening. The study is motivated by an attempt to give a description of the sub-mesoscale vertical convection in the cross-shore plane of an enclosed elongated basin such as the Arabian Gulf where these physical mechanisms are operative. The effect of the addition of wind-forcing in the longshore direction is also investigated. To resolve sub-mesoscale phenomena we find it necessary to employ a model basin which is smaller in its horizontal dimension than the Arabian Gulf. The results of the two dimensional model are presented herein. These results include (i) a detailed description of the evapora-tive-convective adjustment process; (ii) a measure of the convective length scale and vertical velocity; (iii) an assessment of the relative strengths of the buoyancy induced geostrophic current in the alongshore direction and the direct wind induced velocities; (iv) an assessment of the effect of wind on the density structures and (v) an analogy between the forcing by diffusive buoyant source and advective buoyant source.