Intraseasonal variability of the North Brazil Undercurrent forced by remote winds

Veleda, D., Araujo, M., Zantopp, Rainer J. and Montagne, R. (2012) Intraseasonal variability of the North Brazil Undercurrent forced by remote winds Journal of Geophysical Research: Oceans, 117 (C11). C11024. DOI 10.1029/2012JC008392.

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Abstract

Intraseasonal signals with periods of 2 to 3 weeks in near-surface alongshore current measurements are detected from four moorings (K1 - K4) deployed from 2000 to 2004 at the 11{degree sign}S section close to the Brazilian coast as part of the German CLIVAR Tropical Atlantic Variability Project. This section crosses the path of the North Brazil Undercurrent, the most powerful western boundary current in the South Atlantic Ocean. We investigate the origin of this intraseasonal variability of the North Brazil Undercurrentby relating the oceanic oscillation of the alongshore currents to its atmospheric counterpart, the meridional wind stress. On average, the results indicate a well-defined lagged (10 days) correlation (~0.6) structure between meridional wind stress and alongshore currents. The oceanic region with the highest cross-correlations is identified as a relatively narrow band along the Brazilian coast, from 22{degree sign}-36{degree sign}S and 40{degree sign}-50{degree sign}W, bounded in the north by an eastward change in coastline orientation. The cross-wavelet transform establishes the common power between the time series of meridional wind stress and alongshore currents, predominantly during austral winter and spring. These signals propagate equatorward with an alongshore speed of 285{plus minus}63 km day-1, consistent with Coastal Trapped Wave theory.

Document Type: Article
Additional Information: WOS:000311564800002
Keywords: Coastal Trapped Waves; North Brazil Undercurrent; alongshore currents; equatorward propagation; intraseasonal variability; remote wind forcing; WESTERN TROPICAL ATLANTIC; SOUTH EQUATORIAL CURRENT; TRAPPED WAVE THEORY; CONTINENTAL-SHELF; BOUNDARY CURRENT; DRIVEN CURRENTS; STRESS CURL; SEA LEVELS; OCEAN; CIRCULATION
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-PO Physical Oceanography
Refereed: Yes
DOI etc.: 10.1029/2012JC008392
ISSN: 2169-9275
Projects: CLIVAR
Expeditions/Models:
Date Deposited: 22 Nov 2012 12:48
Last Modified: 27 Feb 2018 08:52
URI: http://eprints.uni-kiel.de/id/eprint/19254

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