Crossing of the Equator by the Deep Western Boundary Current in the Western Atlantic Ocean

Abstract

Abstract Property distributions and geostrophic shear from a hydrographic section near 37°W in the Atlantic Ocean show the deep western boundary current (DWBC) in the North Atlantic Deep Water (NADW) established against the western boundary of the Brazil Basin immediately south of the equator (between 2° and 5°S). The DWBC thus has directly crossed the equator to the South Atlantic following the east-southeast trend of the continental slope isobaths. The estimated DWBC transport of NADW is 35 × 106 m3 s−1, similar to other estimates from the tropics discussed here. These large DWBC transports are opposed by flow of deep water to the North Atlantic immediately offshore of the DWBC, with as much as two-thirds of the DWBC transport being returned as these recirculations. One recirculation center is the Guiana Basin north of the equator but extends at least a few hundred kilometers south of the equator; another is visible at 11°S in the Brazil Basin. The degree of connection of these two observed recirculatio...