Snow cover monitoring using multitemporal ERS-1 SAR data

A method is presented for the application of ERS-1 SAR images to snow cover monitoring in high mountain areas. It is based on an image coregistration as well as a geometric and radiometric correction to remove the relief induced distortions. Using the optimal resolution approach ORA synthetic SAR images are calculated to significantly improve the thematic information content. The multitemporal optimal resolution approach MORA uses a sequence of ascending and descending scenes. It builds on the functionality of ORA by coregistering image pairs and extracting geoecophysical parameters through successive ratioing of the backscatter information. Wet snow cover monitoring was done by calculating ratios between the backscattering coefficients of the synthetic SAR images and a snow-free reference scene. The method was applied to a dataset covering the 1993 melting season. The climbing of the snow-line could clearly be detected. The potentials and limitations of the approach are discussed.