A two‐step method for estimating the extent of burnt areas with the use of coarse‐resolution data

The extent of the burnt area for five fires that took place in Greece in July 1998 was estimated with the use of Advanced Very High Resolution Radiometer (AVHRR) data by employing existing methods that use spectral indices for burnt‐pixel detection and relationships between single‐channel reflectance and the fraction of the pixel that has been burnt. The results of these methods were compared with field validation data. The burnt‐pixel detection methods resulted in large omission and commission errors and tended to provide an overestimation of the total burnt area extent while the sub‐pixel methods tended to identify areas as partially burnt, when in fact they were not, thus providing errors of commission. A two‐step method that combines burnt‐pixel identification methods with sub‐pixel techniques was employed in order to overcome the limitations associated with the use of the methods individually. This combined technique provided improved estimations of burnt‐area extent when compared with any of the methods employed individually.