Inter-calibration using desertic sites as a reference target.

The present study is part of an investigation aimed at optimizing the use of desertic sites for absolute or relative calibration of satellite optical sensors. This effort includes characterization of the surface, gathering of climatology or atmospheric data sets, ground- and air-based measurements as well as results of calibration of various sensors over these sites. Post-launch degradation and relative sensitivity of various sensors have been estimated using north african desertic sites as radiometrically stable targets. The selected areas have first been used to cross-calibrate SeaWiFS sensor and POLDER, and then to cross-calibrate AVHRR and POLDER. Extension to other sensors will be presented.