Interpretation of polarimetric ice penetrating radar data over Antarctic ice shelves

We have collected ice penetrating polarimetric radar data on Brunt, George VI and Ronne ice shelves using a vector network analyser as a continuous wave (CW) step-frequency radar. Being a wideband phase sensitive instrument, the radar allowed the vectorial nature of the interaction between radio waves and the ice and reflecting surface to be explored. Single crystals of ice are birefringent not only at optical frequencies but also at radar ones, so in an ice sheet the average crystal orientation fabric determines the overall level of birefringence. The polarisation of radio waves is changed by the birefringent nature of the ice and by the reflecting surface, whether an internal layer or the basal boundary. By transmitting and receiving on orthogonal linearly polarised aerials, we could use a scattering matrix approach to determine the parameters describing the action of the ice and reflecting surface on the polarisation behaviour.

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