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Seasonal variability in the Southwestern Atlantic

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Title Seasonal variability in the Southwestern Atlantic
Names Matano, Ricardo P. (creator)
Schlax, Michael G. (creator)
Chelton, Dudley B. (creator)
Date Issued 1993-10-15 (iso8601)
Note copyrighted by American Geophysical Union
Abstract The circulation of the southwestern Atlantic Ocean is dominated by the Subtropical Gyre
and the confluence of the Brazil and Malvinas currents. Observations indicate that the latitude
of this confluence changes seasonally, lying farther north during the austral winter than during
the summer. This phenomenon has important consequences for the local climate and marine
population, as the latitude of the confluence also marks the boundary between the warm waters
of the subtropical gyre and the cold waters of the Antarctic Circumpolar Current. We present
evidence that these seasonal migrations may be related to change in the transport of both the
Brazil and Malvinas currents. A numerical model forced by climatological wind stress indicates
that the transport of the Brazil Current decreases during winter months and increases during
summer months. Geosat altimeter data corroborate the model results and also indicate that the
transport of the Malvinas Current undergoes a seasonal cycle with phase opposite to that of the
Brazil Current. Our hypothesis is that during the austral summer, a southward displacement of
the latitude of the confluence is coincident with an acceleration of the flow in the subtropical gyre and a weakening of the transport of the Malvinas Current. This situation reverses during the
winter when the Malvinas Current grows stronger, the Brazil Current transport decreases, and
the latitude of the confluence of these two currents moves northward.
Genre Article
Identifier Chelton, D. B., Matano, R. P., Schlax M. G., Seasonal variability in the Southwestern Atlantic, J. Geophys. Res., 98,C10.

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