Fire scar detection in Central Portugal using RADARSAT-1 and ERS-2 SAR data

A comparative study on backscatter returns from multi-temporal RADARSAT-1 and ERS-2 SAR data has been conducted on a fire-disturbed region of Central Portugal. Six images were examined to detect changes between forest and burnt forest areas. A local incidence angle normalization to 23° was applied to allow a comparison between scenes from different beam modes and SAR instruments. A number of widely distributed sample plots were chosen to characterize different vegetation classes. Both sensors were able to discriminate burnt and unburnt classes. However, no discrimination was possible between the three cover type classes considered, neither before nor after the fire. The similar response from both instruments was associated to the volumetric scattering produced on C-band by vegetation. Small differences in backscatter values can only be explained by the soil moisture changes between the dates in which the images were acquired.