An efficient regional energy-moisture balance model for simulation of the Greenland Ice Sheet response to climate change

摘要

In order to explore the response of the Greenland ice sheet (GIS) to climatechange on long (centennial to multi-millennial) time scales, a regionalenergy-moisture balance model has been developed. This model simulatesseasonal variations of temperature and precipitation over Greenland andexplicitly accounts for elevation and albedo feedbacks. From these fields,the annual mean surface temperature and surface mass balance can bedetermined and used to force an ice sheet model. The melt component of thesurface mass balance is computed here using both a positive degree dayapproach and a more physically-based alternative that includes insolationand albedo explicitly. As a validation of the climate model, we firstsimulated temperature and precipitation over Greenland for the prescribed,present-day topography. Our simulated climatology compares well toobservations and does not differ significantly from that of a simpleparameterization used in many previous simulations. Furthermore, thecalculated surface mass balance using both melt schemes falls within therange of recent regional climate model results. For a prescribed, ice-freestate, the differences in simulated climatology between the regionalenergy-moisture balance model and the simple parameterization becomesignificant, with our model showing much stronger summer warming. Whencoupled to a three-dimensional ice sheet model and initialized withpresent-day conditions, the two melt schemes both allow realisticsimulations of the present-day GIS.