| Summary: | Polarimetric SAR observations at long-wavelengths (e.g. L- and P- band) provide the possibility to characterize the near-surface structure of glaciers and ice sheets. The knowledge of such information is crucial for understanding and monitoring the dynamic of ice masses [1]. With dry snow conditions, SAR signal penetrates several meters through snow and ice, interacting with buried features, like ice lenses, air bubbles, etc. The structure of subsurface layers determines the penetration depth of the SAR waves. In a polarimetric SAR (PolSAR) sensor, the penetration capability of microwaves is combined to the additional information brought by the polarization diversity, which provides high sensitivity to scatterers properties [2]. This paper addresses the interpretation of L- and P- band PolSAR measurements over the Austfonna ice-cap, Svalbard, by using the polarimetric scattering model presented in [3]. In detail, two test sites are investigated, which are located in different glacier zones [4] of the ice-cap. Experimental SAR data were collected by the airborne E-SAR sensor of the German Aerospace Center at L- (1.3 GHz) and P-band (0.35 GHz) over the percolation zone and the superimposed ice region of Austfonna, in spring 2007 during the ICESAR campaign. First, a qualitative polarimetric data analysis is performed based on a set of descriptors which includes backscattering coefficients, co-polarization ratio, co-polarization phase difference, entropy and mean alpha angle. Differences appearing between the two sites at both frequencies are discussed and related to the differences in subsurface structure with the support of ground measurements. A polarimetric decomposition, based on the scattering models proposed in [3], is also applied to the SAR data to provide a quantitative estimation of physical parameters at both locations. A final discussion addresses the incongruences observed by comparing the results obtained at L- and P-band over each site. The difference in wavelength turns out to generate significant ...
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