DYNAMICS OF SIGNAL SATURATION WITH CHANNE L 3 OF THE AVHRR (ADVANCED VERY HIGH-RESOLUTION RADIOMETER) - MAJOR HANDICAP OR INFORMATION SOURCE FOR ENVIRONMENTAL MONITORING OF THE SUDAN AND GUINEA

Saturation of data from channel 3 of the Advanced Very High Resolution Radiometer (AVHRR) is used as an indicator of fire activity in the So udano-Sahellien zones of West Africa. Surface phenomena other than fir e are also found to cause channel 3 saturation. The variation in space and time of saturation is found to be a potentially valuable source o f information for environmental monitoring in West Africa. Results sug gest that monitoring the spatial-temporal dynamics of channel 3 satura tion: (1) can help, when used alongside the Normalized Difference Vege tation Index (NDVI), in the definition of new cover classes, particula rly at continental and global scales; (2) could play an important role in modelling energy and water exchanges at the biosphere-atmosphere i nterface; (3) forms a framework for the analysis of fire activity; and (4) could act as a good indicator of rapid ecosystem change.