Climate Dynamics

, Volume 26, Issue 4, pp 429–440

On the northward shift of the West African monsoon

  • Romain Ramel
  • Hubert Gallée
  • Christophe Messager
Article

DOI: 10.1007/s00382-005-0093-5

Cite this article as:
Ramel, R., Gallée, H. & Messager, C. Clim Dyn (2006) 26: 429. doi:10.1007/s00382-005-0093-5

Abstract

The regional climate model (MAR) is used to perform a simulation of the year 1992 over West Africa. It is shown that MAR is able to simulate the main features of the rainy regime over West Africa and especially the discontinuous seasonal progression of the West African Monsoon along the year. One particular feature that is reasonably well reproduced is the abrupt shift of the rain band from 5° to 10°N at the end of June (also called “monsoon jump”). This study suggests that such a phenomenon is associated with the shift of the Saharan heat low between two favourite positions: one being over the Sahelian area (10–15°N) and the other over the Saharan area (20–25°N). These two favourite locations of the heat low are linked to the spatial distribution of surface albedo over West Africa that drives the spatio-temporal location of the surface temperature maxima. A detailed analysis of this “monsoon jump” is performed and the causes of the strong decrease in precipitation that precedes the northward shift of the rain band are also investigated.

Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  • Romain Ramel
    • 1
  • Hubert Gallée
    • 2
  • Christophe Messager
    • 1
  1. 1.Laboratoire des Transferts en Hydrologie et Environnement—Observatoire des Sciences de l’Univers de GrenobleCNRS-UJF-INPG-IRDGrenoble Cedex 9France
  2. 2.Laboratoire de Glaciologie et de Géophysique de l’Environnement—Observatoire des Sciences de l’Univers de GrenobleCNRSGrenobleFrance

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