EFFECTS OF BOTTOM TOPOGRAPHY IN THE LARGE-SCALE CIRCULATION OF THE SOUTHERN-OCEAN

The characteristics of an unforced, stratified f-plane geostrophic flo w over topography are described, and scaling arguments are made to jus tify the use of such a Bow as a first-order approximation to a real, l arge-scale circulation. Consideration of integral constraints then pro vides an insight into the ways in which second-order processes must ba lance the wind forcing. The importance of bottom pressure in this mode l is used to test the scalings and theory on a dataset taken from the Fine Resolution Antarctic Model. Two plots of bottom pressure, each wi th depth dependence filtered out in a different way, confirm the scali ngs producing the following conclusions: The effect of topography on t he bottom boundary condition (no flow through the boundary) is importa nt to the first-order (f-plane geostrophic) circulation; the turning o f horizontal velocities with depth is limited, especially in regions o f strong flow; and a picture of bottom pressure, appropriately filtere d for depth dependence, contains a wealth of valuable information abou t the importance of second-order processes, demonstrating that they ar e most important in particular localized regions associated with topog raphic features.