| Summary: | In June 1991, the NASA/Jett Propulsion Laboratory airborne SAR (AIRSAR) collected the first calibrated multi-channel SAR observations of the Greenland ice sheet. Large changes in radar scattering are detected across different melting zones. In the drysnow zone, Rayleigh scattering from small snow grains dominates at C-band. In the soaked-snow zone, surface scattering dominates, and an inversion technique was developed to estimate the dielectric constant of the snow. The radar properties of the percolation zone are in contrast unique among terrestrial surfaces, but resemble those from the icy Galilean satellites. The scatterers responsible for the percolation zone unusual echoes are the massive ice bodies generated by summer melt in the cold, dry, porous firm. An inversion model is developed for estimating the volume of melt-water ice retained each summer in the percolation zone from multi-channel SAR data. The results could improve current estimates of the mass balance of Greenland, and could help monitor spatial and temporal changes in the strength of summer melt in Greenland with a sensitivity greater than that provided by altimeters.
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