Mass–Balance and Ice–Flow–Law Parameters for East Antarctica

A comprehensive set of ice-velocity and thickness data from traverses within the IAGP study area (bounded by long. 90°E. and 135°E., and north of lat. 80°S.) is compared with steady-state mass-flux calculations based on Scott Polar Research Institute (SPRI) map compilations. The results of previous regional mass-budget estimates are reviewed and followed by a description of the new field measurements and the basis upon which a computer “grid–point” program is used to calculate balance fluxes. A comparison of measured and balance fluxes indicates that the ice sheet in this region of East Antarctica is unlikely to be significantly out of balance. The ratio of average column to surface velocity is discussed and calculated to be 0.89. An analysis of the mean shear strain-rate (VS/Z), versus down-slope basal shear stress (τb=ρgᾱZ), suggests that power flow-law parameters ofn= 3.21 andk= 0.023 bar−nm−1are appropriate for the effective basal shear zone in this region of the Antarctic ice sheet.