Global dynamics of the Antarctic ice sheet
Abstract
The total mass budget of the Antarctic ice sheet is studied with a simple axisymmetrical model. The icesheet has a parabolic profile resting on a bed that slopes linearly downwards from the centre of the ice sheet into the ocean. The mean ice velocity at the grounding line is assumed to be proportional to the water depth. The accumulation rate is a linear function of the distance to the centre. Setting the total mass budget to zero yields a quadratic equation for the steadystate icesheet radius R. Analysis of the equilibrium states sheds light on the sensitivity of the icesheet radius to changes in sea level (S) and precipitation with respect to the present state (P_{rel}). For model parameters obtained by matching the analytical model to the present state of the Antarctic ice sheet, the sensitivity values are dR/dS = 2400 and dR/dP_{rel} = 4000 m/%. The model can also be used to study transient behaviour of the ice sheet. The characteristic relaxation time (efolding time scale) is about 3500 years. Forcing the model with a sealevel and accumulation history over the past few hundred thousands of years yields Antarctic icevolume curves that are similar to those obtained by comprehensive numerical modelling. The current imbalance predicted by the model corresponds to a sealevel rise of 0.25 mm yr^{1}.
 Publication:

Climate Dynamics
 Pub Date:
 March 2002
 DOI:
 10.1007/s003820010210z
 Bibcode:
 2002ClDy...19...85O