Radar absorption, basal reflection, thickness and polarization measurements from the Ross Ice Shelf, Antarctica

Abstract

Radio-glaciological parameters from the Moore's Bay region of the Ross Ice Shelf, Antarctica, have been measured. The thickness of the ice shelf in Moore's Bay was measured from reflection times of radio-frequency pulses propagating vertically through the shelf and reflecting from the ocean, and is found to be 576± 8m. Introducing a baseline of 543 ±7m between radio transmitter and receiver allowed the computation of the basal reflection coefficient, R, separately from englacial loss. The depth-averaged attenuation length of the ice column, 〈L〉 is shown to depend linearly on frequency. The best fit (95% confidence level) is 〈L(v)〉 = (460± 20)-(180±40)vm (20 dB km-1), for the frequencies v = [0.100-0.850] GHz, assuming no reflection loss. The mean electric-field reflection coefficient is √R = 0.82 ±0.07 (1.7dB reflection loss) across [0.100-0.850] GHz, and is used to correct the attenuation length. Finally, the reflected power rotated into the orthogonal antenna polarization is <5% below 0.400 GHz, compatible with air propagation. The results imply that Moore's Bay serves as an appropriate medium for the ARIANNA high-energy neutrino detector.