Backscatter model for the unusual radar properties of the Greenland
Abstract. A number of planetary objects exhltilt unusual radar polarization properties and more recently a similar behavior has been observed over a vast portion of the Eart h‘s surface: the percolation facies of the Greenland Ice Sheet. Surface-based ranging radar data and snow stratigraphy studies...
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| Format: | Text |
| Language: | English |
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1995
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.595.8250 http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/33570/1/94-1351.pdf |
| Summary: | Abstract. A number of planetary objects exhltilt unusual radar polarization properties and more recently a similar behavior has been observed over a vast portion of the Eart h‘s surface: the percolation facies of the Greenland Ice Sheet. Surface-based ranging radar data and snow stratigraphy studies demonstrated that the unusual radar properties of that portion of Greenland are caused by enhanced scattering from massive, large, solid-ice bod-ies buried in the top few meters of the dry, cold, clean snowy surface of the ice sheet and created by seasonal melting and refreezing events. Here, we model the icy inclusions as ran-domly distributed, horizontal and nearly vertical, discrete, dielectric cylinders embedded in a transparent snow medkm. An exact analytical solution is used to compute the scattered field from the cylinders, The model predictions are in good agreement with fully polari-met ric radar observations gathered by an airborne imaging system simultaneously at three radar wavelengths (5.6, 24 and 68 cm) with an incidence angle of the radar illumination varying bet ween 19 and 65 degrees. The diameter and number density of the cylinders that are inferred from the radar data using the backscatter model are consistent with in-situ observations of the icy inclusions, The large radar reflectivity and polarization ratios of the Greenland percolation facies are interpreted as arising from internal reflections of the radar signals in the icy inclusions that first-order scattering models fail to predict. The results compare favorably with predictions from the coherent backseat ter or weak localization the-ory and may provide a complementary framework for interpreting exotic radar echoes from other planet ary objects. Submitted to JGR Planets on September 26, 1994. 1. |
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