Estimating a volumetric backscatter coefficient from in-situ measurements on the Greenland Ice Sheet

The authors obtained in-situ radar backscatter data at several sites on the Greenland Ice Sheet to better relate scattering signatures to firn physical properties. Backscatter measurements were made using an ultra-wide band radar system (.5-18 GHz) for incidence angles between 0 and 50 degrees, with respect to the snow surface. For large angles of incidence (>25/spl deg/) the measured backscatter is dominated by volumetric scattering, as opposed to surface and specular backscatter occurring at near normal incidence. Using the data the authors present a method for estimating the volumetric backscatter coefficient as a function of depth in firn. Results show trends consistent with both seasonal variations and long-term grain growth, which is primarily influenced by the accumulation rate.