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).^[1] 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).^[2] CCSM is maintained by the National Center for Atmospheric Research.

The software design of CCSM 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.^[3] The offline chemical transport model has been described as 'very efficient'.^[4]

The model itself is divided into four component models (land, sea-ice, ocean and atmosphere) connected by a coupler, which exchanges information with each of the component models. It has been suggested by NCAR themselves that because of this, CCSM cannot be considered a single climate model, but rather a framework for building and testing various climate models.^[5]

Ocean model (docn6)

The Ocean model used in CCSM, the Climatological Data Ocean Model (docn), is one of four component models plus the coupler that make up the structure of CCSM. The most recent version is Version 6.0. Unlike the atmosphere model, this component cannot be run as a standalone model; it must be run within the framework of CCSM.^[5] It takes two netCDF datasets as input, then outputs six climate variables to the coupler, to be integrated with the variable produced by the other component models.^[6]

Atmosphere model (CAM)

The atmospheric component of CCSM is the Community Atmosphere Model (CAM). While being the atmospheric model used in the Community Climate System Model, it can also be run as a standalone atmosphere model. The most current version is 3.1, 3.0 being the fifth generation of NCAR atmospheric GCM. On May 17, 2002, its name was changed from the NCAR Community climate Model to reflect the role of the atmosphere model in the new fully coupled climate system.^[7] It shares the same horizontal grid as the land model of CCSM: a 256x128 regular longitude/latitude global horizontal grid (giving a 1.4 degree resolution). It has 26 levels in the vertical.^[8]

Development

The first version of CCSM was created in 1983 as the Community Climate Model (CCM). Over the next two decades it was steadily improved and was renamed CCSM after the Climate System Model (CSM) components were introduced in May 1996.^[1] In June 2004 NCAR released the third version of CCSM, which included new versions of all of the component models. In 2007 this new version of CCSM (commonly given the acronym CCSM3, or the abbreviation NCCCSM^[9]) was used in the IPCC Fourth Assessment Report,^[10] alongside many other GCMs from different countries and institutions. In May 2010 NCAR released CCSM version 4 (CCSM4). On June 25, 2010 NCAR released the successor to CCSM, called the Community Earth System Model (CESM), version 1.0 (CESM1), as a unified code release that included CCSM4 as the code base for its atmospheric component.

References

External links

• CCSM4
• CCSM3
• CCSM2
• CCSM1
• Community Atmosphere Model (CAM), atmospheric component of CCSM