2.3.3. Identification of potential fire pixels
Pixels within the potential fire area are considered as potential fire pixels if (T22N293 K, R2b0.3, and ΔT22N10 K), where ΔT22=T22−T31. These conditions are adopted from the MODIS fire detection algorithm with a change in the T22 threshold, which is attenuated in order to increase the sensitivity to smaller, cooler fires. The T22 threshold is selected based on the statistical analysis of over 30 granules (800 fire pixels) dispersedly distributed in the southeast states in various seasons. The setting of 293 K for T22 threshold can reduce the omission errors caused by the corresponding threshold in the MODIS contextual algorithm, and decrease the number of fire pixels that are mistakenly included in the valid background pixels. The lower T22 threshold also reduces omission errors due to large scan angles, since the radiance of the object decreases at large scan angles and the lower threshold allows small, cool fire pixels at large scan angles to be further processed.