A global survey of surface climate parameters from satellite observations: Preliminary results over Africa

Earth observation satellites provide us with the opportunity to survey the land surface on a frequent and global basis for agronomy applications or climate studies. Meteosat and NOAA satellites have been used in this work to estimate land surface parameters useful for climate modelling, albedo, ground temperature, vegetation index, and to study their time changes on a seasonal and year-to-year basis. Results obtained monthly from 1983 over Africa will be shown and discussed. They include: - the seasonal and interannual variabilities of the surface albedo, and the impact of the vegetation on the surface albedo in the subtropical areas ; - monthly mean values of the downward solar radiation at the surface which can be combined with surface albedo to compute the net solar radiation at the surface; - minimum, maximum and daily range of the surface temperatures in connection with the water budget in the Sahel region; - the relationship between precipitations and the vegetation biomass through the vegetation index in the Sahel region.