Antarctic field measurements of radar backscatter from snow and comparison with ERS-1 altimeter data

Abstract

Two identical Ku band scatterometers were deployed at a number of locations in the region of the Filchner-Ronne ice shelf, Antarctica, during the austral summer '91/92. These were used to investigate the vertical incidence radar properties of the top 10m of firn, and these measurements were compared with those made by the ERS-1 radar altimeter over the region. The radar backscatter coefficient, on the ice shelf was found to remain constant over a period of 18 days, but the value differed significantly from that obtained on the nearby Coats Land plateau. Field measurements, coincident with ERS-1 overpasses, were made throughout a 4-week field season during the three day repeat cycle of the 'Ice Phase' of the satellite's operation. These show spatial agreement with the ERS-1 altimeter backscatter coefficient to within 1dB. Distinct sub-surface layering was detected at several locations, contributing up to 3dB to the total backscattered power with a variation over 30km of 1dB. The major surface factor contributing to the 7dB of spatial and temporal variation of backscatter coefficient, across the ice shelf, is the presence and formation of surface crusts.