A three-dimensional numerical model is developed to simulate the variation with time of the form of the ice sheet in the Shirase basin, Antarctica (Fig.1). The model is composed of two-dimensional grids on which the mass flux of ice is computed so as to satisfy the equation of continuity. Local conditions of the flow of ice, particularly the effect of the depth profile of temperature, are considered. Adopting a simple method for calculating the mass flux developed by the” same authors (Nagao and others 1982) procedures of numerical calculations are simplified. Areal grids of 50 km distances covering the basin are used, paying special attention to the boundary conditions at its margin and glacier tongue.
Results of the calculations show that a nearly stable form of the ice sheet could be obtained after approximately 10 ka when started from 1000 m ice thickness all over the basin. The obtained stable surface topography shows its sensitive dependence on the bedrock topography. There was a tendency for the bottom temperature of the glacier downstream to be higher than the melting point, which may confirm the suggested instability of the ice sheet near the central stream line of Shirase Glacier (Mae 1979).