A Model of Buoyant Throughflow: With Application to Branching of the Tsushima Current

Abstract

A reduced-gravity model is used here to investigate the dynamics of a buoyant flow through a strait driven by pressure difference of the adjoining basins. Assuming the flow to be hydraulically controlled so that the transport is maximized, flow structures in the upstream basin, during its transit through the strait and along the downstream coast, are determined. It is found in particular that the combined effect of friction exerted by the sill and stretching of the buoyant layer as it exits the strait may cause the downstream flow to exhibit two velocity maxima?along the layer outcrop and the coastal boundary. When applied to the Tsushima Current of the Japan/East Sea, the required conditions for branching are amply satisfied, the model thus provides a plausible explanation of this observed feature. In addition, a favorable comparison between predicted and observed transports supports the hydraulic control of the flow.