Backscattering properties of a wet snow cover derived from DEM corrected ERS-1 SAR data

Abstract

This paper presents the results from a study on the use of Digital Elevation Model (DEM) corrected and absolute calibrated ERS-1 SAR data for snow parameter extraction in mountainous areas. Several ERS-1 SAR data sets, Landsat Thematic Mapper (TM) and in situ measurements from Kvikne area in south Norway have been available. This paper focus on the results obtained from analysis of simultaneously acquired SAR and TM data from 31 May 1992. The SAR derived backscattering coefficient, sigma0, from a wet snow cover versus local incidence angle have been found to correspond well to surface scattering model given by Kirchoff stationary phase approximation. A linear fit between the surface model and the SAR data gave values for the surface slope and the dielectric constant which corresponds to values obtained from field measurements. The SAR data have been slope effect reduced using both modified Muhleman scattering model and surface scattering model. Spatial analysis of the relation between TM derived snow parameters and slope effect reduced SAR data have been performed in areas where exposed rock/sparsely vegetated areas are partly covered with a wet snow cover. sigma0 is found to linearly decrease as the TM derived snow ratio increases. The slope effect reduction process is shown to significantly increase the correlation coefficient between sigma0 and TM derived snow ratio.