Large-Scale Numerical Modelling of the Antarctic Ice Sheet

Abstract

A large-scale dynamic numerical model of the Antarctic ice sheet has been developed to study its present state of ice flow and mass balance as well as its response to long-term changes of climate or sea-level. The flow of ice over a two-dimensional grid is determined from the ice thickness, the basal shear stress, the bedrock depth, and ice flow parameters derived from velocities of existing ice sheets. The change in ice thickness with time is governed by the continuity equation involving the ice flux divergence and the ice accumulation or ablation. At the ice sheet seaward boundary, a floating criterion and floating ice thinning rate apply. Bedrock depression with a time-delayed response dependent on the history of the ice load is also included. A 61 × 61 point grid with 100 km spacing has been used to represent the ice-sheet surface, bedrock, and accumulation rate. The model has been used to simul a te the growth of the present ice sheet and i ts reaction to changes of sea-level, bedrock depression, accumulation rate, ice flow parameters, and the iceshelf thinning rate. Preliminary results suggest that the present ice sheet is not in equilibrium but rather is still adjusting to changes of these parameters.