Circulation atmosphérique et sécheresse

Centre national de recherches météorologiques, 42 avenue G. Coriolis, 31057 Toulouse Cedex

Abstract

Droughts are caused by an extended deficit of precipitations associated with anomalies in the general circulation of the atmosphere. An examination of the hydric balance of our planet shows indeed the essential role played by the general circulation of the atmosphere in the transport of atmospheric water vapour. The atmospheric circulation, which is subject to natural fluctuations of dynamical origin, can furthermore be influenced by the variations of its surface boundary conditions, like ocean surface temperatures, soil albedo and roughness. Persistent anomalies of these parameters can produce displacements of the precipitation zones, leading to droughts in some areas.