Research note: Monthly rainfall grids in West and Central Africa
ORSTOM, today IRD (“Institut de Recherche pour le Développement”), is a French institute of research that has been conducting research in Africa for the last 60 years. Since this period, agroclimatologists and hydrologists of IRD have never stopped collecting, validating and completing hydroclimatic data over West and Central Africa. In the view of modelling runoff in this part of the world, our team, HydroSciences Montpellier (HSM), manages an hydroclimatic and environmental database (SIEREM). Using all the collected pluviometric data, we have been calculating monthly rainfall on a regular 0.5° * 0.5° gridding, each mesh corresponding to approximately 2,750 km2. To assess the value of these gridded rainfall data, we compared them with those provided by the Climate Research Unit of University of East Anglia (CRU-UEA). The IRD and CRU grids are very similar but the former IRD grids are computed from more stations and have proven to be more reliable when predicting stream flows using two rainfall-runoff models. These grids are available from free of charge from SIEREM database website ( http://www.hydrosciences.fr/sierem/index.htm).