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Community Multiscale Air Quality Modeling System (CMAQ)

Access CMAQ Source Code

CMAQ is a suite of Fortran 90 programs that work in concert to estimate ozone, PM, toxic compounds, and acid deposition throughout the troposphere.  The model requires significant computational resources to run and therefore requires a multi-processor computer running Linux.   CMAQ users should be comfortable with Linux scripting conventions and have some familiarity with the Fortran programming language. Users should also have some familiarity with atmospheric structure, and the physical and chemical processes that occur in the atmosphere.  

The CMAQ source code is currently housed on GitHub. GitHub is a web-based code repository hosting service. It allows for easier code maintenance and distribution. You can download model code from the command line or from your browser.  Users are also encouraged to create an account through the Community Modeling and Analsysis System (CMAS) Center to take advantage of the training, conferences and software support provided by the center.   Visit the CMAS Center website to create a user account. EXIT

Command Line Download for CMAQ Base Model from GitHub

CMAQ versions 4.7.1 through 5.2 are available from EPA's CMAQ GitHub Site.EXIT To download the CMAQ source code and scripts from the command line follow the following example template:

git clone -b [MODEL] [MODEL]

The following [MODEL] options are available:


Note that CMAQ-ISAM and CMAQ-DDM-3D are part of the download for CMAQv5.0.2.  CMAQ-DDM-3D has been updated based on CMAQv5.2 and is a separate branch on the GitHub repository called 5.2_DDM-3D.  More information on CMAQ-ISAM and CMAQ-DDM is provided on the CMAQ Models page.

Direct Download for CMAQv5.2

Click on the links below to download a .zip file containing the CMAQv5.2 base model or the CMAQv5.2 DDM-3D version. A link is also provided to our EPA ftp site where you can download directions and code for constructing the WRF-CMAQ coupled model (file name="WRF3.8_CMAQ5.2_TwoWay_Model.tar.gz"). 

File type Release date File Size Dependency
CMAQv5.2.1 Model source code and scripts March 2018 16 MB None
CMAQv5.2 Model source code and scripts  June 30, 2017 16 Mb None
CMAQv5.2 DDM-3D source code and scripts Sept 29, 2017 16.2 Mb None
WRF3.8-CMAQ5.2 Coupled Model building scripts June 30, 2017 438 Kb

CMAQv5.2 Model, WRF3.8 Model

Getting Started with CMAQ

  • Check out the "Getting Started" Tutorial for directions on how to prepare your Linux system for installing and running CMAQ.  A complete description of the CMAQ system is provided in the CMAQ User's Guide on GitHub.  Links to available tutorials, the User's Guide and other scientific documentation are provided on the CMAQ Documentation page.  
  • Directions for constructing the WRF-CMAQ coupled model are available from the Release Notes for CMAQv5.2.  A sample run script, twoway_model_run_script, is in the WRFv3.8_CMAQv5.2_TwoWay_Model.tar.gz file under the script subdirectory. (The link to the .tar.gz file is provided in the table above.)
  • Input and output data for the CMAQv5.2 benchmark can be used to test the build of both the base and coupled models.  Directions on how to download the data can be found on the Model Inputs and Test Case Data page.  Note that there is no benchmark data for v5.2.1.
  • Technical support and questions about this release should be directed to Help Desk at CMAS. Exit