USE OF A METEOROLOGY MODEL TO CORRECT ATMOSPHERIC EFFECTS IN NOAA-AVHRR DATA

This paper addresses the issue of determining an operational atmospher ic water vapour correction scheme for satellite data in Sahelian regio ns. The 5S model (Simulation of Satellite Signal in the Solar Spectrum ) was run with two data sets of water vapour content. The first data s et was obtained from radiosonde measurements made in Niamey. The secon d set was derived from the forecasting model (resolution of 1-degrees latitude and longitude) of Meteo France and the European Centre for Me dium-Range Weather Forecasting (ECMWF). The radiosonding network in Sa hel is too sparse to map the atmospheric water vapour content with acc uracy. The advantage of the meteorological model compared to point mea surements is its additional information on water vapour content variab ility and easy access for operational needs. The two sources of data w ere compared for reliability and accuracy. Finally, the two methods we re compared through biomass production assessment of food crops in sou thwestern Niger, using the normalized difference vegetation index (NDV I) and biomass measurements.