The Community Ice Sheet Model (CISM) v2.1
As mass loss from the Greenland and Antarctic ice sheets accelerates, climate modelers recognize the importance of dynamic ice sheet models for predicting future mass loss and sea level rise. The Community Ice Sheet Model (CISM) version 2.1 has been significantly improved and, as a result of these developments, CISM produces more realistic simuations of Greenland, both in stand-alone runs and as part of Earth System Model simulations.
CISM gives a realistic steady-state simulation of the Greenland ice sheet with present-day climate forcing on a moderate resolution, regular 4-km grid. It has been integrated in version 2 of the Community Earth System Model, where it is being used for Greenland simulations under past, present and future climates. The code is open-source and includes extensive documentation and test case support.
We describe and evaluate version 2.1 of the Community Ice Sheet Model (CISM). CISM is a parallel, 3D thermomechanical model, written mainly in Fortran, that solves equations for the momentum balance and the thickness and temperature evolution of ice sheets. CISM’s velocity solver incorporates a hierarchy of Stokes-flow approximations, including shallow shelf, depth-integrated higher-order, and 3D higher-order. CISM also includes a suite of test cases, links to third-party solver libraries, and parameterizations of physical processes such as basal sliding, iceberg calving, and sub-ice-shelf melting. The model has been verified for standard test problems using the LIVVkit package, including the ISMIP-HOM experiments for higher-order models, and has participated in the initMIP–Greenland initialization experiment. In multi-millennial simulations with modern climate forcing on a 4-km grid, CISM reaches a steady state that is broadly consistent with observed flow patterns of the Greenland ice sheet. CISM has been integrated into version 2 of the Community Earth System Model, where it is being used for Greenland simulations under past, present and future climates. The code is open-source with extensive documentation, and remains under active development.