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Laboratory for Atmospheric and Space Physics


Below are atmospheric and radiative transfer models utilized or maintained by the Toon Group. The group maintains an extensive wiki page with details on how to run many of these models.

Model: Community Aerosol Model (CAM3)

Source: NCAR/CGD

The latest version of NCAR’s CESM launched in 2018 is part of a series of global atmosphere models developed for climate research communities. CAM and WACCM also serve as the atmospheric component of the Community Earth System Model (CESM).

Model: Community Aerosol and Radiation Model for Atmospheres (CARMA)

Source: University of Colorado, NASA Ames Research Center

CARMA is a general-purpose sectional microphysics code that has been used to study a wide variety of aerosols in planetary atmospheres. It originated from a one-dimensional stratospheric aerosol code developed by Turco et al. (1979) and Toon et al. (1979) that included both gas phase sulfur chemistry and aerosol microphysics. The model was improved and extended to three dimensions as described by Toon et al. (1988). Extensive updates of the numerics continue to be made. Standard versions of the model are maintained at NCAR and distributed to the community. A wide community of users, including our group at the University of Colorado, works with this code and continues to improve it.

CARMA applications
CARMA has been applied to almost every cloud and aerosol on Earth, as well as those on Venus, Mars, Titan, and exoplanets. Please see the References section for a link to published papers via Brian’s LASP web page and vita.

Model: Distributed Hydrodynamic Aerosol and Radiative Modeling Application (DHARMA)

Source: NASA Ames Research Center

The dynamics framework of DHARMA is a large-eddy simulation code originally called HUSCI and developed by David Stevens (now at LLNL) (Stevens and Bretherton, JCP, 1996). As a postdoc at LLBL, Dr. Stevens extensively rewrote the model to be massively parallel (with 2D decomposition) using MPI (Stevens et al., JAS, 2002). DHARMA also includes aerosol and cloud microphysics and radiative transfer components that are based on CARMA, which required making the microphysics model suitable for use in a 3D framework. To do so, during the 1990s at NASA Ames Research Center Eric Jensen and Andy Ackerman rewrote the aerosol and cloud microphysics model originally developed by Brian Toon and Rich Turco in the 1970-80s (Toon et al., 1988). This rewrite largely consisted of generalizing the particle bin structure, decoupling the time stepping of coagulation and condensation (making the latter time-stepping independent within each grid cell), and replacing the advection algorithms used for condensation and sedimentation. Then Dr. Ackerman merged CARMA (including it’s two-stream radiative transfer model, Toon et al. 1989) into the large-eddy simulation codes (first the serial version and later the parallel version). The name DHARMA was coined to described the massively parallel version of the merged model (the CARMA microphysics and radiative transfer components are optional components of DHARMA).

Model: Whole-Atmospheric Community Climate Model (WACCM3)


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 from the High Altitude Observatory’s (HAO) modeling of the upper atmosphere, the Atmospheric Chemistry Division’s (ACD) modeling of the middle atmosphere, and the Climate and Global Dynamics Division’s (CGD), modeling of the troposphere, all of whom use the NCAR Community Climate System Model (CCSM) as a common numerical framework.