Welcome to CCSM

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Model Release

The Community Atmosphere Model version 3.0 (CAM 3.0) was released along with CCSM 3.0 on Wednesday, June 23, 2004. CAM 3.0 is the latest CCSM atmosphere model and is the first major update since CAM 2.0. This version of the model includes updates to both the science and software engineering of the model.

Highlights of the software improvements include:

• Performance improvements for all three dynamical cores in the areas of:
• load balancing
• interprocess communication
• physics and dynamics decompositions
• compiler optimizations
• memory requirements
• vectorization
• Inclusion of a single column model (SCAM).
• New run-time controls for performance and science options.
• Ability to output a contiguous subset of columns to the history tape instead of a full field.

New science developments include:

• Updated parameterizations for prognostic cloud water, cloud ice, precipitation, and cloud fraction.
• Inclusion of a Slab Ocean Model (SOM).
• Inclusion of ISCCP cloud simulator to simulate ISCCP statistical cloud diagnostics.
• Diagnostic treatment of aerosols (sulfate, dust, sea salt, carbon, and volcanic).
• Optional prognostic treatment of sulfate aerosols.
• Improved energy conservation.
• Modifications to longwave interaction with water vapor.
• Updates to shortwave scheme for trace gas absorption
• Atmosphere-land interface now supports rain and snow phases.

Concurrent with this release of CAM are a new Scientific Description and User's Guide. Please see these documents for details of the new model.

Richard Neale, AMWG Liaison, email: rneale@ucar.edu