Science et changements planétaires / Sécheresse


An analysis of West African rainfall events during two constrasting climate periods (1951-1970 and 1971-1990) Volume 13, issue 2, Juin 2002


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Hydro-Québec/CRSNG, ALCAN, Chaire en hydrologie statistique, INRS-ETE, Université du Québec, Canada.
  • Page(s) : 95-104
  • Published in: 2002

The compound Poisson exponential (LCPE) distribution was applied to daily rainfall during the two periods 1951-1970 and 1971-1990 in West Africa (0°-5° in longitude; 6°-16° in latitude). For this site and for each of these periods the distributional characteristics of two components of rainfall, the mean numbers of events per day (lambda) and the mean depth of events (mu), have been estimated. These two components constitute the parameters of the model. The analysis of these parameters allows the climatology of the regimes to be mapped over the last 40 years with a high resolution and it points out that the drought observed since 1970 is due to the decrease in the number of events within the rainy season, rather than to a change in the mean depth per event.