Path of the North Atlantic Deep Water in the Brazil Basin

• Published in: Journal of Geophysical Research: Oceans
• Main Authors: Zangenberg, Norbert, Siedler, Gerold
• Format: Article in Journal/Newspaper
• Language: English
• Published: AGU (American Geophysical Union) 1998
• Subjects: Mid-Atlantic Ridge; Western Basin; NADW; North Atlantic Deep Water; North Atlantic
• Online Access: https://oceanrep.geomar.de/id/eprint/6855/; https://oceanrep.geomar.de/id/eprint/6855/1/97JC03287.pdf; https://doi.org/10.1029/97JC03287

Recent hydrographic sections and high-quality historical data sets are used to determine geostrophic currents at subtropical latitudes in the western basin of the South Atlantic. Levels of no motion are determined from water mass information and a mass balance constraint to obtain the transport field of North Atlantic Deep Water (NADW) in this region. The incoming NADW transport of about 20 Sv from the north at 19 degrees S appears to be balanced by only one third of this transport leaving in the south and two thirds leaving to the east or northeast at the Mid-Atlantic Ridge. A simple model is proposed to determine the cause of the NADW branching. It is shown that potential vorticity preservation in the presence of topographic changes leads to a similar flow pattern as observed, with branching near the Vitoria-Trindade-Ridge and also an eastward turning of the southward western boundary current at about 28 degrees S, the latitude where a balance of planetary vorticity change and stretching can be expected.