An interactive Greenland Ice Sheet in EC-Earth3: Model Evaluation

<p>In order to capture the complex interactions and feedbacks between large ice sheets and the climate system, two-way coupled climate &#8211; ice sheet models are needed, which allow a dynamical ice sheet to be influenced by the climate state and vice versa. Here, we present the coupled model system EC-Earth3-GrIS, consisting of the global climate model EC-Earth3 two-way coupled to the PISM Parallel Ice Sheet Model for Greenland. The ice sheet model receives surface forcing in the form of surface mass balance (SMB) and surface temperature and returns ice sheet topography, and fluxes of basal melt and ice discharge to EC-Earth3. Two methods for obtaining the SMB are tested: (1) the SMB is directly calculated in EC-Earth3 at a horizontal resolution of ~80 km and regridded to the PISM ice sheet model at 5 km horizontal resolution; (2) a downscaled measure of the SMB at the resolution of the ice sheet model is calculated using the Copenhagen Ice Snow Surface Energy Balance Model (CISSEMBEL) forced with the 6-hourly surface fluxes from EC-Earth3. The implications of the downscaling of the SMB and the influence on the ice sheet initial state are evaluated, and the state of the Greenland Ice Sheet in the EC-Earth3 preindustrial climate is assessed.&#160; &#160;&#160;</p>