Analysis Of Sar Polarimetric Signatures Of Pine Forests

Abstract

Prior to the analysis, calibration of polarimetric SAR data is important if the full potential of the information contained in the radar polarization signatures is to be exploited. Therefore, a calibration procedure has been applied to the full complex high resolution data set, using Klein's algorithm valid for the calibration of scattering matrix. Phase and cross-talk calibration is performed using clutter statistics, whereas relative amplitude calibration (channel imbalance) is performed using the integrated approach, based on responses of trihedral corners deployed within the scene. Then an attempt is done to obtain an absolute calibration using the theoretical corner radar cross section. A method is proposed to extend the absolute calibration to the whole szene (range and azimuth) using saturated response of old pine forest stands disseminated within the scene. Then multifrequency polaTimetric signatures of pine stands are synthesized from the Stokes matrix derived from the calibrated scattering matrix. The polarimetric signatures are interpreted, based on the main scattering mechanisms occuring within forest canopies (double-bounce scattering from trunk-ground and branch-ground interactions, scattering from needles, branches and trunk). These mechanisms are dependent on 1) polarization state and frequency of the impinging wave and 2) electromagnetic characteristics of the stands, related to biophysical parameters of interest such as height, density and biomass.