Response of the Southern Benguela upwelling system to fine-scale modifications of the coastal wind

Type Article
Date 2016-04
Language English
Author(s) Desbiolles Fabien1, 2, Blanke Bruno1, Bentamy Abderrahim2, Roy C.1
Affiliation(s) 1 : UMR 6523 CNRS Ifremer IRD UBO, LPO, Brest, France.
2 : IFREMER, Ctr Brest, LOS, Brest, France.
Source Journal Of Marine Systems (0924-7963) (Elsevier Science Bv), 2016-04 , Vol. 156 , P. 46-55
DOI 10.1016/j.jmarsys.2015.12.002
WOS© Times Cited 15
Keyword(s) Eastern boundary upwelling system, Momentum flux forcing, Wind profile, Numerical modeling, Scatterometry
Abstract We analyze the results of a regional model of the Southern Benguela upwelling system forced by wind stress fields derived from QuikSCAT observations. Two different horizontal resolutions are considered for the wind stress: QS25 and QS50, corresponding to native 25 and 50 km grids, respectively. The differences between both products highlight the primary importance of fine-scale momentum fluxes for both the structure and intensity of the wind- and wind curl-driven upwelling. Using QS25, we show that the coastal Ekman transport is reduced, leading to a warmer SST and a reduced oceanic coastal jet. QS25 finer wind stress curl patterns also favor the development of a stronger and shallower poleward undercurrent. The addition of a coastal wind correction to QS25 lets us investigate the possible implications of an imbalance between Ekman transport and Ekman pumping: a wind reduction in the coastal band often reduces the SST cooling, but the two mechanisms compensate each other when the characteristic length scales of the coastal upwelling and the orography-induced wind drop-off are similar.
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