Abstract
On the frame of the AMMA-EU project, sensitivity experiments for an Atlantic Equatorial mode (AEM) which origin, development and damping resembles the observed one during the last decades of the 20th century, has been analysed in order to investigate the influence on the anomalous summer West African rainfall. Recent studies raise the matter of the AEM influence on the next Pacific ENSO episodes and also on the Indian Monsoon. This paper evaluates the response of four different atmospheric global circulation models, using the above-mentioned AEM sensitivity experiments, to study the tropical forcing associated with the Atlantic Niño mode. The results show a remote signal in both the Pacific and Indian basins. For a warm phase of the AEM the associated southward location of the ITCZ, with rising motions over the Equatorial Atlantic, leads to a global subsidence over the rest of the tropics, weakening the Asian Monsoon and favouring the La Niña conditions in the central Pacific. Although ocean–atmosphere coupled experiments are required to test the latter hypothesis, the present studies shows how the AEM is able to influence the rest of the tropics, a result with important implications on ENSO seasonal predictability.
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Acknowledgments
This study was supported by the EU-AMMA project and the Spanish MEC project CGL2006-04471. Based on French initiative, AMMA was built by an international scientific group and is currently funded by a large number of agencies, especially from France, UK, US and Africa. It has been the beneficiary of a major financial contribution from the European Community’s Sixth Framework Research Programme. Detailed information on scientific coordination and funding is available on the AMMA International website http://www.amma-international.org. The authors thank Javier García-Serrano and Elsa Mohino for his very useful comments on the manuscript, and the two anonymous reviewers for their constructive suggestions and comments.
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This paper is a contribution to the special issue on West African Climate, consisting of papers from the African Multidisciplinary Monsoon Analysis (AMMA) and West African Monsoon Modeling and Evaluation (WAMME) projects, and coordinated by Y. Xue and P. M. Ruti.
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Losada, T., Rodríguez-Fonseca, B., Polo, I. et al. Tropical response to the Atlantic Equatorial mode: AGCM multimodel approach. Clim Dyn 35, 45–52 (2010). https://doi.org/10.1007/s00382-009-0624-6
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DOI: https://doi.org/10.1007/s00382-009-0624-6