Greenland ice sheet interaction with HadCM3

The HadCM3 GCM has been coupled with a dynamic 3-D ice sheet model of Greenland that includes a visco-elastic solid Earth model. The GCM runs the ice sheet model inline once a year, providing it with precipitation and temperature anomalies. The input is interpolated to the ice sheet model grid, and the ice sheet model then calculates ablation, based on a degree-day scheme, ice dynamics and basal rebound. The ice sheet model passes back to the GCM a new orography and fresh water fluxes which are utilised by the GCM over the subsequent year. Iceberg calving fluxes are applied evenly to the sea region adjacent to Greenland whilst runoff enters the ocean through 'river' outlets. When the orographic changes result in a GCM grid cell changing from ice to land, or vice versa, the grid cell characteristics are updated in line with the HadCM3 land surface scheme. A multiple century experiment starting from the present day ice sheet, with 4 x CO2 atmospheric concentration, is being undertaken to determine the rate of ice ablation, the impact of icesheet change on the HadCM3 sea level rise, oceanic and atmospheric circulation, and the effect of orographic changes in the ice sheet on its mass balance.