The baroclinic transport of the Antarctic Circumpolar Current south of Africa

Abstract

Five hydrographic transects at nominal longitudes 0°E and 30°E, and fourteen expendable bathythermograph (XBT) sections near the former longitude are used to study the baroclinic transport of the Antarctic Circumpolar Current (ACC) between Africa and Antarctica. The bottom-referenced geostrophic transport between the Subtropical Front and the ACC Southern Boundary is 147 ± 10 Sv. Estimating the transport from the XBTs using a technique previously employed south of Australia proves delicate because of an irregular bathymetry and water mass variations. It nevertheless confirms ACC transports around 150 Sv. Gathering these and other estimates from the Atlantic sector suggests that, while North Atlantic Deep Water is injected in the current west of 35°W, a partially compensating loss of Deep Circumpolar Water occurs east of this longitude. Another transport increase from 0°E to 30°E might reflect southward transfer across the Subtropical Front south of the Agulhas retroflection. Copyright 2005 by the American Geophysical Union.