A C-band backscatter model for lake ice in Alaska

ERS-1 SAR imagery of lake ice growing on shallow tundra lakes in northern Alaska shows interesting radar backscatter variations. Based on the analysis of ice cores from these lakes, a multi-layer backscatter model comprised of the following elements has been developed: 1) specular air-ice, ice-water and ice-frozen soil boundaries; 2) an ice layer of variable thickness; 3) ice sub-layers with air inclusions of variable density, size and shape, including spheres, prolate spheroids, and cylinders of finite length. Preliminary model results confirm that backscatter is a sensitive function of the presence of a specular ice-water interface, with a roughly 40-times greater reflectivity than from an ice-frozen soil interface. The model has also been tested using bubble data derived from ice cores in April 1992. The modelled backscatter is compared with backscatter derived from ERS-1 SAR images obtained at the same time as the fieldwork