The dynamic role of ridges in a Beta-plane channel : towards understanding the dynamics of large scale circulation in the Southern Ocean

Abstract

Abstract : In this thesis, the dynamic role of bottom topography in a Beta-plane channel is systematically studied in both linear homogeneous and stratified layer models in the presence of either wind stress or buoyancy forcing. In these studies, the structure of the geostrophic contour plays a fundamental role, and the role of bottom topography is looked at from two different angles. It is shown that blocking all the geostrophic contours leads to two different physical processes in which bottom topographic form drag is generated and enables geostrophic flow in a Beta - plane channel to support a net cross-channel volume transport. It is demonstrated that by blocking all the geostrophic contours in the presence of a sufficiently high ridge, the dynamics of both source-sink and wind driven circulations in a Beta - plane is similar to that in a closed basin. Potential vorticity, Geostrophic contour, Form drag.