A deep western boundary current in the South Indian basin

Abstract

A section of closely-spaced hydrographic stations was occupied for the first time across the western boundary of the South Indian Basin, above the flank of the Kerguelen Plateau. A northward-flowing deep boundary current was found, whose transport is estimated geostrophically to be 6 × 10 6 m 3 s −1. The section crossed meanders of fronts within the Antarctic Circumpolar Current, with transports estimated as 5−15 × 10 6 m 3 s −1. The source of bottom water is concluded to be the neighbouring Antarctic shelf, including the Adélie coast and a component from the Ross Sea. Changes in the deep temperature-salinity relation are consistent with an increased component of relatively salty bottom water from the Ross Sea, over the time period 1972–1992.