Optimum polarimetric PALSAR information extraction for peatland classification and fire damage assessment

Abstract

The complementarity of the “scattered” and “received” wave polarization signatures is demonstrated for enhanced characterization of peatlands and surrounding upland forest scattering. Polarimetric L-band ALOS-PALSAR collected in the Athabasca oil sand exploration region, with peatlands and upland forests partially affected by multiple wildfire, are used. It is shown that the scattered wave polarization signature [1], which represents the explicit variations of the degree of polarization (DoP) and the total scattered intensity RO with transmitted polarization, permits enhanced discrimination of treed bogs from upland forests, and improved identification of fire damages in peat-lands and surrounding forests. The technique introduced in [2] for scattered wave optimization is used as a convenient method for efficient exploitation of the scattered wave polarization signature. The Touzi decomposition [3] is adopted for the optimization of the received wave polarization signature. The unique potential of the scattering type phase generated with the Touzi decomposition is confirmed for enhanced discrimination of poor fens from bogs. These two important pealand classes cannot be separated with the scattered wave optimization, the conventional multi-polarization (HH-HV - VV) channels, the Freeman and Cloude-Pottier decompositions [4], [5]. Finally, the Touzi decomposition is combined with the extrema of the scattered wave main parameters (DoP and RO) for optimum extraction of polarimetric PALSAR information. The comparison with optical Landsat-TM confirms the valuable added information that long penetrating polarimetric L-band PALSAR can provide for enhanced peatland classification and efficient assessment of peat health in burned peatlands.