Altimeter Measurements of the Volume Transport Through the Drake Passage

Abstract

From in situ measurements it has been inferred that the variability of flow through the Drake Passage down to 250&n does not depend upon depth (barotropic flow). By making this assumption it is possible to calculate the variability of the volume transport from the surface slope as measured by a radar altimeter. It is shown that it is not possible to use data from individual passes as there is too much noise on the observations. However by averaging all the data in a ten day period in boxes north and south of the Passage an estimate of the variability comparable to the in situ observations is obtained. Using an additional two boxes in the centre of the Passage shows that most of the variability is in the northern half. The variability in the centre is negatively correlated with both the north and south.