Circulation Induced by River Inflow in Well Mixed Water over a Sloping Continental Shelf

Abstract

The pressure field over a sloping continental shelf subject to freshwater runoff at the coast can be resolved into a nearly two-dimensional dynamic height field and a residual field, the latter arising from the interaction of baroclinity and topography. The residual field is essentially three-dimensional and so constituted as to supply the fluid for the baroclinic alongshore flow off a coastal source of buoyancy associated with the cross-isobath density gradients. The intensity of the induced residual circulation (its total transport in m³ s⁻¹) varies directly with the buoyancy input and bottom slope, and inversely with the zero-order alongshore flow velocity and Coriolis parameter. Over the Mid-Atlantic Bight continental shelf the runoff-induced residual circulation makes a generally weak contribution to the observed mean flow field. It could, however, be more important over a low-latitude shelf subject to high runoff.