The Regime of the Western Part of the Ross Ice Shelf Drainage System

Abstract

AbstractThe net mass budget is estimated for the western part of the Ross Ice Shelf drainage system. The area of the system is (1.75±0.26) × 106km.2, and the drainage periphery extends along the eastern flank of the Trans-Antarctic Mountains between lat. 77° 58′ S., long. 164° 37′ E. and lat. 85° 27′ S., long. 147°50′ discharge is estimated from vertical cross-sections and corresponding ice-movement data for eight outlet glaciers. Free-air gravity anomalies, corrected for the effect of terrain above the glacier surface, are used to determine cross-sections of valleys by comparison with theoretical gravity profiles for several two-dimensional valley models. These data provide a basis for estimating the rate of ice discharge from the plateau, which is compared with the estimated rate of net accumulation at the surface, to determine the net budget of the ice sheet in the region. Representative mean rates of ice discharge measured in different types of glaciers are approximately 0.25 × 1015g. km.−1yr.−1in outlet glaciers with large basins, and 0.05 × 1015g. km.−1yr.−1in outlet glaciers with small basins. Taking into account the snowshcd area and the rate of accumulation, the rate of ice discharge in cirque and piedmont glaciers is estimated at about 0.02 × 1015g. km.−1yr.−1The difference ((48±29) × 1015g. yr.−1) between mass input ((96±25) × 1015g. yr.−1) and mass output ((48±15) × 1015g. yr.−1) is large enough relative to the estimated standard error to indicate a probable positive net budget.