Climate Dynamics

, Volume 35, Issue 1, pp 29–43 | Cite as

A multi-model approach to the Atlantic Equatorial mode: impact on the West African monsoon

  • T. Losada
  • B. Rodríguez-Fonseca
  • S. Janicot
  • S. Gervois
  • F. Chauvin
  • P. Ruti
Article

Abstract

This paper is focused on the West African anomalous precipitation response to an Atlantic Equatorial mode whose origin, development and damping resembles the observed one during the last decades of the XXth century. In the framework of the AMMA-EU project, this paper analyses the atmospheric response to the Equatorial mode using a multimodel approach with an ensemble of integrations from 4 AGCMs under a time varying Equatorial SST mode. The Guinean Gulf precipitation, which together with the Sahelian mode accounts for most of the summer West African rainfall variability, is highly coupled to this Equatorial Atlantic SST mode or Atlantic Niño. In a previous study, done with the same models under 1958–1997 observed prescribed SSTs, most of the models identify the Equatorial Atlantic SST mode as the one most related to the Guinean Gulf precipitation. The models response to the positive phase of equatorial Atlantic mode (warm SSTs) depicts a direct impact in the equatorial Atlantic, leading to a decrease of the local surface temperature gradient, weakening the West African Monsoon flow and the surface convergence over the Sahel.

Keywords

West African Monsoon Tropical Atlantic variability Tropical teleconnections 

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Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • T. Losada
    • 1
  • B. Rodríguez-Fonseca
    • 1
  • S. Janicot
    • 2
  • S. Gervois
    • 2
  • F. Chauvin
    • 3
  • P. Ruti
    • 4
  1. 1.Universidad Complutense de MadridMadridSpain
  2. 2.LOCEAN/IPSL, CNRS, Université Pierre et Marie CurieParisFrance
  3. 3.GAME/CNRM, Météo-France/CNRSToulouseFrance
  4. 4.Progetto Speciale Clima Globale, Ente Nazionale per le NuoveTecnologieRomeItaly

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