Depolarization of radio waves can distinguish between floating and grounded ice sheets

• Published in: Journal of Glaciology
• Main Authors: Woodruff, A.H.W., Doake, C.S.M.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: International Glaciological Society 1979
• Subjects: Antarc*; Antarctica; Ice Sheet; Ice Shelf; Journal of Glaciology
• Online Access: http://nora.nerc.ac.uk/id/eprint/525228/; https://doi.org/10.3189/S0022143000029853

Polar ice is now thought to be marginally birefringent at radio echo-sounding frequencies. An experiment on the polarization behaviour of 60 MHz radio echoes from the bed of both ice shelf and land ice in Antarctica showed a marked difference in the returned polarization. It appears that differences in electrical properties or roughness of the reflecting boundary cannot explain our results. We suggest that there is a large change in the birefringence of the ice sheet at the hinge zone, caused by the effect of tidal strain on crystal orientation. This would imply a minimum value of the radio-frequency anisotropy in permittivity for the single crystal of (0.52±0.8)%. Therefore polarization changes could allow floating and grounded ice to be distinguished.