VALIDATION OF BACKSCATTER MODELS FOR LEVEL AND DEFORMED SEA-ICE IN ERS-1 SAR IMAGES

Backscatter models for level and deformed ice are evaluated based on i n situ measurements of Baltic sea-ice and the results are compared wit h coincident ERS-1 Synthetic Aperture Radar (SAR) data. A two-layer sc attering model is used for level ice with a dry snow cover. The result s show that ice surface scattering dominates in the pack ice, while sc attering from the ice-water interface and ice volume scattering are im portant in the fast ice where the salinity is very low. For deformed i ce which consists of large ice blocks, a two-component model is formul ated and shown to be independent of the block size distribution. By ev aluating the model based on in situ data it is concluded that specular reflections dominate, whereas the small-scale roughness is of less im portance. An approach for data inversion is also described, which esti mates the ice surface roughness from ERS-1 SAR images during dry snow conditions.