Propagation and origin of warm anomalies in the Angola Benguela upwelling system in 2001

Type Article
Date 2007-12
Language English
Author(s) Rouault M1, Illig S2, 5, Bartholomae C3, Reason C1, Bentamy Abderrahim4
Affiliation(s) 1 : Univ Cape Town, Dept Oceanog, ZA-7701 Rondebosch, South Africa.
2 : NASA, Jet Propuls Lab, Pasadena, CA USA.
3 : Natl Marine Informat & Res Ctr, Swakopmund, Namibia.
4 : Inst Francais Rech Exploitat Mer, Plouzane, France.
5 : Legos, Toulouse, France.
Source Journal of Marine Systems (0924-7963) (Elsevier), 2007-12 , Vol. 68 , N. 3-4 , P. 473-488
DOI 10.1016/j.jmarsys.2006.11.010
WOS© Times Cited 52
Keyword(s) Ocean atmosphere interaction, Tropical Atlantic variability, Angola Benguela upwelling system
Abstract Warmer than average sea surface temperatures were observed by the Tropical Rainfall Mission Microwave Imager in the Angola Benguela Current system in late austral summer 2001 and persisted for about three months. These coastal anomalies extended offshore by 1 to 4 degrees longitude and were not due to local ocean atmosphere interaction or relaxation of the upwelling favorable southerly winds. Instead, they were remotely forced by ocean atmosphere interaction in the Tropical Atlantic. Satellite remote sensing and a linear ocean model suggest that relaxation of trade winds along the equator triggered Kelvin waves that crossed the basin within a month in early 2001. Westerly wind anomalies were also observed in December 2000 and January 2001 over most of the Tropical Atlantic contributing to a warm preconditioning due to an enhancement of the oceanic annual cycle. This led to abnormal sea level heights near equatorial Africa that propagated southwards along the coast towards the Angola Benguela Frontal zone. This process increased the seasonal penetration of warm and salty water of tropical origin into the Angola Benguela upwelling system. (C) 2006 Elsevier B.V All rights reserved.
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