The Whole-Atmosphere Community Climate Model (WACCM) is a comprehensive numerical model, spanning the range of altitude from the Earth's surface to the thermosphere. The development of WACCM is an inter-divisional collaboration that unifies certain aspects of the upper atmospheric modeling of HAO, the middle atmosphere modeling of ACD, and the tropospheric modeling of CGD, using the NCAR Community Climate System Model (CCSM) as a common numerical framework.

The initial version of WACCM (WACCM-1b) incorporates physical and chemical processes required to investigate coupling between atmospheric regions from the surface to 140 km. Further addition of upper thermospheric physics and chemistry, much of which is currently operating in HAO's TIME GCM, will eventually allow the model to extend upward to about 500 km. WACCM is built upon the numerical framework of CGD's Community Climate System Model (CCSM), and is envisaged as a flexible model environment, whose domain and component modules can be configured according to the specific problem under study.

The atmosphere component of CCSM, the Community Atmosphere Model (CAM) has been extended to the upper boundary at 140 km by:

1. incorporating non-LTE IR transfer above 60 km;
2. including shortwave heating and photolysis from Lyman-alpha to EUV
   
3. extending the parameterization of gravity wave breaking and diffusion above the mesopause;
4. including molecular diffusion and diffusive separation effects above 90 km from the TIME-GCM; and
5. incorporating and extending the chemical scheme from ACD's MOZART-3 photochemistry model

Please click on the links below the page header to learn more about the WACCM project.