Community Climate System Model

The Community Climate System Model (CCSM) is a coupled global climate model (GCM) developed by the University Corporation for Atmospheric Research (UCAR) with funding from the National Science Foundation (NSF), the Department of Energy (DoE), and the National Aeronautics and Space Administration (NASA). The coupled components include an atmospheric model (Community Atmosphere Model), a land-surface model (Community Land Model), an ocean model (Parallel Ocean Program), and a sea ice model (Community Sea Ice Model). CCSM is maintained by the National Center for Atmospheric Research (NCAR).

Its software design assumes a physical/dynamical component of the climate system and, as a freely available community model, is designed to work on a variety of machine architectures powerful enough to run the model. The CESM codebase is mostly public domain with some segregable components issued under under open source and other licenses. The offline chemical transport model has been described as "very efficient".

The model includes four submodels (land, sea-ice, ocean and atmosphere) connected by a coupler that exchanges information with the submodels. NCAR suggested that because of this, CCSM cannot be considered a single climate model, but rather a framework for building and testing various climate models.

The Climatological Data Ocean Model (docn) is recently at version 6.0. It must be run within the framework of CCSM rather than standalone. It takes two netCDF datasets as input and sends six outputs to the coupler, to be integrated with the output of the other submodels.

The Community Atmosphere Model (CAM) can also be run as a standalone atmosphere model. Its most current version is 3.1, while 3.0 was the fifth generation. On May 17, 2002, its name was changed from the NCAR Community Climate Model to reflect its role in the new system. It shares the same horizontal grid as the land model of CCSM: a 256×128 regular longitude/latitude global horizontal grid (giving a 1.4 degree resolution). It has 26 levels in the vertical.

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