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Ocean Science An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/os-2017-59
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
04 Aug 2017
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Ocean Science (OS).
Transport Variability of the Brazil Current from Observations and a Model
Claudia Schmid1 and Sudip Majumder2 1National Oceanic and Atmospheric Administration
2Cooperative Institute for Marine and Atmospheric Studies, University of Miami, Miami, FL, USA
Abstract. Brazil Current transports from observations and a model are analyzed to improve our understanding of its structure and variability. The observed transports are derived from a three-dimensional field of the velocity in the South Atlantic covering the years 1993 to 2015 (hereinafter called Argo & SSH). The mean transport of the Brazil Current from 3.8 ± 2.2 Sv (1 Sv is 106 m3s−1) at 25° S to 13.9 ± 2.6 Sv at 32° S, which corresponds to a mean slope of 1.4 ± 0.4 Sv per degree. The Hybrid Coordinate Model (HYCOM) has somewhat higher transports than Argo & SSH (5.2 ± 2.7 Sv and 18.7 ± 7.1 Sv at 25° S and 32° S), but these differences are small when compared with the standard deviations. Overall, the observed latitude dependence of the transport of the Brazil Current is in agreement with the wind-driven circulation in the super gyre of the subtropical South Atlantic. A mean annual cycle with highest (lowest) transports in austral summer (winter) is found to exist at selected latitudes (24° S, 35° S and 38° S). The significance of this signal shrinks with increasing latitude, mainly due to the mesoscale and interannual variability. In addition, it is found that the interannual variability at 24° S is correlated with the Southern Annular Mode and the Niño 3.4 index. A coupled EOF of the meridional transport and the sea level pressure is used to improve the understanding of the impact of these ocean indexes.

Citation: Schmid, C. and Majumder, S.: Transport Variability of the Brazil Current from Observations and a Model, Ocean Sci. Discuss., https://doi.org/10.5194/os-2017-59, in review, 2017.
Claudia Schmid and Sudip Majumder
Claudia Schmid and Sudip Majumder
Claudia Schmid and Sudip Majumder

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Short summary
An analysis of observed transports in the Brazil Current shows a factor 9 increase between its origin and terminus. The 23 year time series reveals an annual cycle with a maximum in austral summer whose significance decreases on the way south and varies interannually. In addition, 2–4 year long phases with relatively high/low values are observed. A correlation of the transport with the Southern Annular Mode (Niño 3.4 index), with a lag of 6 (8) months, is present at 24 degrees S.
An analysis of observed transports in the Brazil Current shows a factor 9 increase between its...
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