Much of the research work on the dynamics of large ice sheets has employed the “flowline approach” (e.g. Reference YoungYoung 1981). However, present-day computer facilities now allow the use of two- and three-dimensional models as well. This opens up the possibility of simulating the transient behaviour of large ice sheets, including the effects of irregular bedrock topography, ice shelves, accumulation distribution, etc.
This presentation reports an attempt to construct a time-dependent, two-dimensional (i.e. vertically integrated) model of the entire Antarctic ice sheet. The basic model has been described in Reference OerlemansOerlemans (1982). On a grid of 100 km spacing, it calculates horizontal ice-mass discharge using a constant flow parameter, bedrock adjustment, and the distribution of ice shelves. The evolution of the ice sheet is then obtained from the continuity equation. In this model the ice-accumulation rate depends on temperature, surface slope and distance to open water.
The model has recently been refined by including a calculation of the temperature field in the ice sheet and the associated feedback on the ice-mass discharge. This involves the dependence of internal deformation on ice temperature as well as increased sliding when basal water is present.
Results from this model version indicate that a large part of the West Antarctic ice sheet is always subject to basal melting, even if surface temperature drops by 5 K. The East Antarctic ice sheet, on the other hand, shows a tendency to behave periodically, much in the same way as described in Reference OerlemansOerlemans (1983). The period of oscillation is typically 10 ka but depends strongly on such factors as ice-accumulation rate, sea-level temperature, and particularly on how the effect of basal water production on ice-mass discharge is parameterized.
Future work will concentrate on this last point, and also on how reduction of normal pressure by buoyancy effects (Reference Budd, Keage and BlundyBudd and others 1979) modifies the evolution of the ice sheet. An attempt will then be made to simulate the Holocene retreat of the Antarctic ice sheet.
