Publication Date:
2009-09-11
Description:
In order to explore the response of the Greenland ice sheet (GIS) to climate change on long (centennial to multi-millennial) time scales, a regional energy-moisture balance model has been developed. This model simulates seasonal variations of temperature and precipitation over Greenland and explicitly accounts for elevation and albedo feedbacks. These fields are used to force a high resolution ice sheet model through the annual mean surface temperature and mass balance. The melt component of the mass balance is computed here using both a conventional positive degree day approach and a more physically-based alternative. As a validation of the model, we first simulated temperature and precipitation over Greenland for the prescribed, present-day topography of Greenland and compared them with empirical data. For the present-day climate, simulated surface boundary conditions for the GIS do not differ significantly from those of a simple parameterization used in many previous simulations. However, for a prescribed, ice-free state, the differences in simulated climatology and surface mass balance between the regional energy-moisture balance model and the conventional approach become significant, with our model showing much stronger summer warming. When coupled to a high resolution, three-dimensional ice sheet model and initialized with present-day conditions, the two melt schemes both allow sufficiently realistic simulations of the present-day GIS. However, when starting from ice-free conditions, two different equilibrium states are achieved, depending on the choice of melt scheme.
Print ISSN:
1994-0432
Electronic ISSN:
1994-0440
Topics:
Geography
,
Geosciences
