Developments and evaluation of ice sheet model IcIES2 for Antarctic configuration

We present our development of the Ice sheet model for Integrated Earth-system Studies (IcIES2) for the Antarctic ice sheet configuration as a model development for CMIP7-ISMIP7. The flow of the ice is calculated with the shallow ice approximation (SIA) and shallow shelf approximation (SSA). To represent the migration of grounding lines, we use the grounding line flux boundary condition of Schoof (2007), following previous implementations (Pollard and DeConto 2012; 2020). The ice velocity fields are calculated using a hybrid approach that combines the SIA and SSA approximations, based on the ratio of basal sliding velocity to the depth-averaged velocity from the SIA solution. We perform sensitivity experiments on ice-sheet model parameters using the present-day bedrock topography and surface mass balance to obtain a reasonable present-day Antarctic ice-sheet configuration. We also perform experiments with an abrupt increase in sub-shelf melting to evaluate the model response to reduced ice shelf buttressing and marine ice sheet instability.