Universität zu Köln

Cabos, William ORCID: 0000-0003-3638-6438, Sein, Dmitry V. ORCID: 0000-0002-1190-3622, Pinto, Joaquim G., Fink, Andreas H. ORCID: 0000-0002-5840-2120, Koldunov, Nikolay V., Alvarez, Francisco, Izquierdo, Alfredo, Keenlyside, Noel and Jacob, Daniela (2017). The South Atlantic Anticyclone as a key player for the representation of the tropical Atlantic climate in coupled climate models. Clim. Dyn., 48 (11). S. 4051 - 4070. NEW YORK: SPRINGER. ISSN 1432-0894

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Abstract

The key role of the South Atlantic Anticyclone (SAA) on the seasonal cycle of the tropical Atlantic is investigated with a regionally coupled atmosphere-ocean model for two different coupled domains. Both domains include the equatorial Atlantic and a large portion of the northern tropical Atlantic, but one extends southward, and the other northwestward. The SAA is simulated as internal model variability in the former, and is prescribed as external forcing in the latter. In the first case, the model shows significant warm biases in sea surface temperature (SST) in the Angola-Benguela front zone. If the SAA is externally prescribed, these biases are substantially reduced. The biases are both of oceanic and atmospheric origin, and are influenced by ocean-atmosphere interactions in coupled runs. The strong SST austral summer biases are associated with a weaker SAA, which weakens the winds over the southeastern tropical Atlantic, deepens the thermocline and prevents the local coastal upwelling of colder water. The biases in the basins interior in this season could be related to the advection and eddy transport of the coastal warm anomalies. In winter, the deeper thermocline and atmospheric fluxes are probably the main biases sources. Biases in incoming solar radiation and thus cloudiness seem to be a secondary effect only observed in austral winter. We conclude that the external prescription of the SAA south of 20A degrees S improves the simulation of the seasonal cycle over the tropical Atlantic, revealing the fundamental role of this anticyclone in shaping the climate over this region.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Cabos, William UNSPECIFIED orcid.org/0000-0003-3638-6438 UNSPECIFIED Sein, Dmitry V. UNSPECIFIED orcid.org/0000-0002-1190-3622 UNSPECIFIED Pinto, Joaquim G. UNSPECIFIED UNSPECIFIED UNSPECIFIED Fink, Andreas H. UNSPECIFIED orcid.org/0000-0002-5840-2120 UNSPECIFIED Koldunov, Nikolay V. UNSPECIFIED UNSPECIFIED UNSPECIFIED Alvarez, Francisco UNSPECIFIED UNSPECIFIED UNSPECIFIED Izquierdo, Alfredo UNSPECIFIED UNSPECIFIED UNSPECIFIED Keenlyside, Noel UNSPECIFIED UNSPECIFIED UNSPECIFIED Jacob, Daniela UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-229593
DOI:	10.1007/s00382-016-3319-9
Journal or Publication Title:	Clim. Dyn.
Volume:	48
Number:	11
Page Range:	S. 4051 - 4070
Date:	2017
Publisher:	SPRINGER
Place of Publication:	NEW YORK
ISSN:	1432-0894
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language AIR-SEA INTERACTION; SEASONAL CYCLE; OCEAN; VARIABILITY; CIRCULATION; BIASES; SST; TELECONNECTIONS; PACIFIC Multiple languages Meteorology & Atmospheric Sciences Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/22959