Estimating net solar radiation balance from satellite data for the Southern Super-Site of the HAPEX SAHEL Experiment

Reliable estimates of net solar radiation over large areas with reasonable resolution in space and time require the inclusion of satellite data. METEOSAT measurements provide information every half an hour, which can be used as a basic element for estimating net solar fluxes at the surface. Additional data are needed both for relating top of the atmosphere fluxes to surface solar net fluxes and for converting measured METEOSAT VIS count values into reflected radiances. Net solar fluxes are calculated with an algorithm, that depends on solar zenith angle, which can be calculated directly as function of geographic position and time and on cloud type and the amount of precipitable water. NOAA data are added to this algorithm to test their applicability as input data and to validate them with additional measurements from the HAPEX SAHEL Experiment.