In the MODIS version 3 active fire

In the MODIS version 3 active fire detection algorithm (Kaufman et al., 1998), sensitivity to relatively small fires were sacrificed in order to reduce persistent false alarms over certain surface types during the day time (Justice et al., 2002a). An enhanced contextual fire detection algorithm (Giglio et al., 2003) was recently used for MODIS version 4 fire products, in which the sensitivity to small, cool fires increased. This algorithm achieved significantly lower false alarm rates by using several solar reflectance channels to reject false alarms, and by adjusting the potential fire threshold and contextual thresholds in the earlier version of the MODIS contextual algorithm.