OS Ocean Science OS Ocean Sci. 1812-0792 Copernicus Publications Göttingen, Germany 10.5194/os-8-1041-2012 Deep Western Boundary Current transport variability in the South Atlantic: preliminary results from a pilot array at 34.5° S Meinen C. S. 1 Piola A. R. 2 Perez R. C. 1 3 Garzoli S. L. 1 Atlantic Oceanographic and Meteorological Laboratory, Miami, Florida, USA Servicio de Hidrografía Naval, and Universidad de Buenos Aires, UMI IFAECI/CONICET/CNRS, Buenos Aires, Argentina Cooperative Institute for Marine and Atmospheric Studies, University of Miami, Miami, Florida, USA 29 11 2012 8 6 1041 1054 Copyright: © 2012 C. S. Meinen et al. 2012 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://os.copernicus.org/articles/8/1041/2012/os-8-1041-2012.html The full text article is available as a PDF file from https://os.copernicus.org/articles/8/1041/2012/os-8-1041-2012.pdf

The first direct estimates of the temporal variability of the absolute transport in the Deep Western Boundary Current (DWBC) at 34.5° S in the South Atlantic Ocean are obtained using just under one year of data from a line of four pressure-equipped inverted echo sounders. Hydrographic sections collected in 2009 and 2010 confirm, based on neutral density, temperature, salinity, and oxygen values, the presence of the DWBC, one of the main deep pathways of the Meridional Overturning Circulation. Both data sets indicate that the DWBC reconstitutes itself after breaking into eddies in the western sub-tropical Atlantic near 8° S. The amplitude and spectral character of the DWBC transport variability are comparable with those observed in the North Atlantic, where longer records exist, with the DWBC at 34.5° S exhibiting a transport standard deviation of 25 Sv and variations of ∼ 40 Sv occurring within periods as short as a few days. There is little indication of an annual cycle in the DWBC transports, although the observational records are too short to be definitive. A Monte Carlo-style analysis using 27 yr of model output from the same location as the observations indicates that about 48–60 months of data will be required to fully assess the deep transport variability. The model suggests the presence of an annual cycle in DWBC transport, however its statistical significance with even 27 yr of model output is low, suggesting that seasonal variations in the model are weak.

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