Bottom currents derived from a shipborne ADCP on WOCE cruise A11 in the South Atlantic

Abstract

This paper is divided into two parts: the first describing an enhancement of the shipborne ADCP system and the second describing information about bottom currents that have been obtained therefrom on the cruise from Punta Arenas to Cape Town. An improved heading measurement has a marked effect on currents determined from the ADCP when under way. The cruise data from this instrument has been reprocessed, replacing the observations of the gyrocompass with those from a GPS3DF unit. Differences, or cross-track bottom currents, are significantly above noise only in the Argentine Basin; three regions are identified there. In the Falkland Current strong barotropic components (16 to 40 cm s-1 northward) augment the baroclinic transport fourfold to 50 Sv. The second region of significant bottom flow is in the confluence zone (Brazil and Falkland Current Extension). The third region is contiguous with and east of the confluence zone. Measurements appear to confirm an anticyclonic flow about the Zapiola Drift. -from Authors