The Sahelian standardized rainfall index revisited.

The article presents a study which aims to clarify the usefulness and relevance of the Standard Precipitation Index (SPI) in measuring the Sahelian rainfall, as well as to determine the needed precautions for interpreting it. It discusses the robustness of SPI value in method deviations, and the significance of a global value of Sahelian rainfall despite its spatial variability. It also looks into the updates on the climatological conditions observed over the Sahel in the 1950-2006 period.