Interannual variability of the Tropical Atlantic independent of and associated with ENSO: Part II. The South Tropical Atlantic

Handoh, Itsuki C., Bigg, Grant R., Matthews, Adrian J. and Stevens, David P. (2006) Interannual variability of the Tropical Atlantic independent of and associated with ENSO: Part II. The South Tropical Atlantic. International Journal of Climatology, 26 (14). pp. 1957-1976. ISSN 1097-0088

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Abstract

Two dominant ocean-atmosphere modes of variability on interannual timescales were defined in Part I of this work, namely, the North Tropical Atlantic (NTA) and South Tropical Atlantic (STA) modes. In this paper we focus on the STA mode that covers the equatorial and sub-tropical South Atlantic. We show that STA events occurring in conjunction with ENSO have a preference for the southern summer season and seem to be forced by an atmospheric wave train emanating from the central tropical Pacific and travelling via South America, in addition to the more direct ENSO-induced change in the Walker circulation. They are lagged by one season from the peak of ENSO. These events show little evidence for other-than-localised coupled ocean-atmosphere interaction. In contrast, STA events occurring in the absence of ENSO favour the southern winter season. They appear to be triggered by a Southern Hemisphere wave train emanating from the Pacific sector, and then exhibit features of a self-sustaining climate mode in the tropical Atlantic. The southward shift of the inter tropical convergence zone that occurs during the warm phase of such an event triggers an extra tropical wave train that propagates downstream in the Southern Hemisphere. We present a unified view of the NTA and STA modes through our observational analysis of the interannnual tropical Atlantic variability.

Item Type: Article
Faculty \ School: Faculty of Science > School of Environmental Sciences
Faculty of Science > School of Mathematics
Depositing User: David Stevens
Date Deposited: 01 Dec 2010 14:12
Last Modified: 19 Aug 2020 23:32
URI: https://ueaeprints.uea.ac.uk/id/eprint/15911
DOI: 10.1002/joc.1342

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