Origin of fine-scale wind stress curl structures in the Benguela and Canary upwelling systems

Type Article
Date 2014-11
Language English
Author(s) Desbiolles Fabien1, 2, Blanke Bruno1, 2, Bentamy Abderrahim2, Grima Nicolas1, 2
Affiliation(s) 1 : CNRS, UBO, IFREMER, Lab Phys Oceans,IRD,UMR 6523, Brest, France.
2 : IFREMER, Lab Oceanog Spatiale, Ctr Brest, Brest, France.
Source Journal Of Geophysical Research-oceans (0148-0027) (Amer Geophysical Union), 2014-11 , Vol. 119 , N. 11 , P. 7931-7948
DOI 10.1002/2014JC010015
WOS© Times Cited 12
Keyword(s) wind stress, upwelling, SST-wind interactions
Abstract Numerous studies have shown the primary importance of wind stress curl in coastal upwelling dynamics. The main goal of this new analysis is to describe the QuikSCAT surface wind stress curl at various scales in the Benguela and Canary upwelling systems. The dominant spatial pattern is characterized by cyclonic curl near continental boundaries and anticyclonic curl offshore, in association with equatorward alongshore (upwelling favorable) wind stress. At a smaller scale, we demonstrate the sensitivity of the QuikSCAT wind stress curl to coastal processes related to sea surface temperature (SST) mesoscale fluctuations by presenting a linear relationship between the curl and crosswind SST gradients. Despite the spatial and temporal sensitivity of the underlying thermal coupling coefficient, a local analysis of the fraction of the curl ascribed to SST variability shows that SST is a main driver of the wind stress curl variability and magnitude over the upwelling extension zone (∼100–300 km from the coast) in both the Canary and Benguela systems. Closer to the shore, the curl patterns derived from QuikSCAT observations are only loosely related to SST-wind interactions. As a working hypothesis, they can also be associated with the coastline geometry and orographic effects that are likely to play an important role in local cooling processes.
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