Meridional Transport across a Zonal Channel: Topographic Localization

Abstract

Experiments are performed using a two-layer isopycnic numerical model in a zonal channel with a large meridional topographic ridge in the lower layer. The model is forced only by a steady meridional volume transport in the upper layer, and develops a current structure similar to the Antarctic Circumpolar Current. Meridional volume flux across time-mean geostrophic streamlines is found to be due to a combination of the geostrophic eddy bolus flux and the lateral Reynolds stress. The proportion of each depends on the strength of the forcing. The Reynolds stress increases with the forcing, while the bolus flux is relatively constant. Topography localizes the eddy fluxes at and downstream of the topography, where eddy energies are greatest. The strength of the zonal transport is governed by the onset of baroclinic instability and so is relatively insensitive to the strength of the meridional transport.