ENVISAT ASAR WIDE SWATH BACKSCATTER DYNAMICS OF THE SIBERIAL BOREAL FOREST FIRE SCAR

摘要

Wildfires significantly affect the boreal ecosystem ofrnSiberia. However, records on burnt areas and fire impactrnare still not satisfactory in Russia. The dense smokernfrom active burning and the persistent cloud coversrnimpeded the application of optical sensors to therndetection of burnt area in Siberia forest during thernsummer fire season. The high resolution SAR data arernof limited use for burnt area identification because ofrnthe enormous size of boreal Russia. In this paper, thernmedium resolution (150 meters) ENVISAT wide swathrnSAR data (ASAR_WSM) were investigated throughrnanalyzing the backscatter dynamics of fire scars inrnSiberia boreal forest. We firstly compared seven timernseries backscatter of ASAR data in burnt forest andrnadjacent unburnt forest, then applied PrinciplernComponent Analysis to pre and post fire images forrndetecting the burnt area change and finally we comparedrnthe visibility on ASAR images among fire scars formedrnin different years. Results show that 1.) ASAR WSM isrnvery useful in detecting burnt area in Siberia forest; 2.)rnthe period from May to early July is optimal time forrndetecting fire scars by ASAR wide swath in borealrnforest of Siberia and the detectability corresponded withrnlocal weather conditions; 3.) Multitemporal images arernmore useful in detecting older fire scars. The resultsrnsuggest that ENVISAT wide swath SAR is a useful datarnsource for operational burnt area identification overrnlarge areas.