| Summary: | The most effective way of determining the rate of elevation change of the Earth's large ice sheets using radar altimeters is to examine the difference in the elevation measured on ascending and descending orbits. This crossover difference has a static and time-varying component, and by isolating the time-varying part, one can construct a time series of the ice sheet elevation change. The static component of the crossover difference arises as a result of an anisotropic dependence of the extinction coefficient on the angle between the radar polarization and wind-induced features of the firn. Here, the static crossover difference observed by CryoSat-2 over the Antarctic ice sheet is examined, and a simple model is developed to explain the observed pattern. There is an excellent agreement between the modeled results and the observations, calling into question the results of previous studies of the same phenomenon with different radar altimeters.
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