Airborne Radio Echo-Sounding in Shirase Glacier Drainage Basin, Antarctica

Abstract

Airborne radio echo-so unding was carried out in order to measure the thickness of the ice sheet in the Shirase Glacier drainage basin and map the bedrock topography. It was found that the elevation of bedrock was approxim ately at sea-level from Shirase Glacier to 100 km up-strea m of the glacier and thereafter it was 500-100 m hi gher. Investigation of the echo intensity reflected from the bedrock indicates that at ice thicknesses less than 1000 m absorption was about 5.2 dB/ lOO m, but at greater ice thicknesses echo intensity did not depend upon the ice thickness but became approximately constant. Where ice thicknesses were greater than 1000 m in the main flow area of the Shirase Glacier drainage basin, the reflection strengths of about 9 dB were greater than outside the basin. Since the increase in echo intensity was considered to be due to the existence of water, the strong echo observed in the main part of the basin supported an hypothesis that the base of the basin was wet and the ice sheet was sliding on the bedrock.

Crystal orientation fabrics within the Antarctic ice sheet revealed by a multipolarization plane and dual‐frequency radar survey

“…This thinning is not compensated by changes in surface mass balance and it could be caused by decreases in the basal drag [Mae and Naruse, 1978]. Previous radar surveys revealed that there are wet subglacial conditions in this area of thinning [Ohmae et al, 1984;Mae and Yoshida, 1987].…”

Ice-dynamic conditions of Shirase Glacier, Antarctica, inferred from ERS SAR interferometry

“…Normally, one Table 1. Measurements and averaged strain rates at the sides of the boxes (1) 171 (5) 368 (5) " xy est (10^3 a^1)^137 (5)^196 (6)^91 (6) " xy west (10^3 a^1) 1 9 1( 5 ) 5 4( 6 ) 9 3( 6 ) " yy up (10^3 a^1) 1 9( 6 ) 2 2( 9 ) 4 4( 9 ) " yy down (10^3 a^1) 6( 6 ) 4 4( 9 ) 7 9( 9 ) " xxup (10^3 a^1) 9( 7 )6( 9 ) 8( 9 ) " xxdown (10^3 a^1)^47 (7) 7 (9)^45 (9) Notes: Ice thickness is taken fromWada and Mae (1981) and Mae and Yoshida (1987); surface elevation from Bamber and Bindschadler (1997). Uncertainties, determined from error propagation, are given in parentheses.…”