The Los Alamos National Laboratory is pleased to announce the release of the Community Ice Sheet Model (CISM) version 2.0, a next-generation ice sheet model for use in predicting ice sheet evolution in a changing climate. CISM 2.0 is freely available to the glaciology and climate modeling communities. It serves as the ice dynamics component of the Community Earth System Model (CESM), which is one of the first global climate models to include coupled, dynamic ice sheets. The starting point for CISM 2.0 is the Glimmer ice sheet model developed at the University of Bristol and elsewhere. With CISM 2.0, the original Glimmer model has been extended to include higher-order ice dynamics and scalable parallelism. This work has been done by the U.S. Department of Energy with contributions from the National Center for Atmospheric Research, the University of Montana, the University of Colorado, New York University, the University of Bristol, the University of Edinburgh, Swansea University, and the University of Zurich. CISM 2.0 runs on a regular mesh using a mixture of finite-difference, finite-volume, and finite-element methods. While written in Fortran 90, it includes and allows for software interfaces to code written in C++. CISM 2.0 is open-source software licensed under the GNU Lesser General Public License (LGPL).
CISM 2.0 includes the following new features relative to the Glimmer and Glimmer-CISM models:
* Robust, parallel, 2D and 3D, higher-order accurate approximations to the Stokes momentum balance (Blatter-Pattyn, SSA, L1L2)
* 3D, parallel mass and temperature transport
* Software interfaces to modern C++ based solver libraries (e.g., Trilinos
* Replacement of Autotools build system with Cmake build system
* Addition of new higher-order test cases, including several with analytical solutions
* Re-ordering of time step to be fully consistent with explicit forward Euler scheme
* New high-level "cism_driver", which replaces and reproduces functionality of several old drivers and allows for more flexible integration of additional and/or external dycores
* Re-arrangement of directory structure
* Modifications to Glint coupling software to support coupling to CESM and other climate models that compute the surface mass balance external to the ice sheet model
* New and updated documentation
CISM 2.0 will be hosted by the CISM Github organization (A download link for an archive of the code is also available from the CISM website). More information, including full documentation of the code and information on user mailing lists, can be found at the CISM website.