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 in situ measurements of Baltic sea-ice and the results are compared with coincident ERS-1 Synthetic Aperture Radar (SAR) data. A two-layer scattering model is used for level ice with a dry snow cover. The results show that ice surface scattering dominates in the pack ice, while scattering from the ice-water interface and ice volume scattering are important in the fast ice where the salinity is very low. For deformed ice which consists of large ice blocks, a two-component model is formulated and shown to be independent of the block size distribution. By evaluating the model based on in situ data it is concluded that specular reflections dominate, whereas the small-scale roughness is of less importance. An approach for data inversion is also described, which estimates the ice surface roughness from ERS-1 SAR images during dry snow conditions.