On the baroclinic structure of the Brazil Current-Intermediate Western Boundary Current system at 22°-3°S

Abstract

The baroclinic structure of the Brazil Current(BC)-Intermediate Western Boundary Current (IWBC) at 22*-23*S was investigated. A reanalysis of the pioneer velocity profile measurements of the TRANSCOBRA Experiment [Evans and Signorini, 1985] revealed that the BC-IWBC system is about 75-80% baroclinic. Mapped velocity structure showed flow reversal at about 450 m, an IWBC thickness of 1200 m and core velocities exceeding 0.30 m s-1. Total (baroclinic) transports for BC (southwestwards) and IWBC (northeastwards) were 5.6 (4.2) Sv and 3.6 (4.1) Sv, respectively. The strong baroclinic character of the BC-IWBC system and the lack of direct velocity observations in the area yielded us to propose the use of the cross-shelf version of the Princeton Ocean Model to generate absolute baroclinic velocities from hydrographic data. These velocities presented a similar reversal depth, and the transports of about 6-7 Sv for both BC-IWBC were also comparable to values reported in the literature. Copyright 2004 by the American Geophysical Union.