An official website of the United States government.

We've made some changes to EPA.gov. If the information you are looking for is not here, you may be able to find it on the EPA Web Archive or the January 19, 2017 Web Snapshot.

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 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 5.3 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] https://github.com/USEPA/CMAQ.git [MODEL]

The following [MODEL] options are available:

 master   (lastest version = 5.3)
 5.2.1 
 5.2 
 5.2_DDM-3D 
 5.1 
 5.0.2
 5.0.1
 5.0
 4.7.1

Note that CMAQ-ISAM is now included in the CMAQv5.3 base model.  CMAQ-DDM-3D is currently only available based on CMAQv5.2 and is a separate branch on the GitHub repository called 5.2_DDM-3D.  CMAQ-DDM-3D will be updated to CMAQv5.3 in the near future. More information on CMAQ-ISAM and CMAQ-DDM is provided on the CMAQ Models page.

Direct Download for CMAQv5.3

Click on the links below to download a .zip file containing the CMAQv5.3 base model or the CMAQv5.2 DDM-3D version.  You can download directions and code for constructing the WRF-CMAQ coupled model from the CMAS Center Google Drive or the EPA Anonymous FTP server (file name="WRF4.1.1_CMAQ5.3_Coupled_Model_20190828.tar.gz"). 

File type Release date File Size Dependency
CMAQv5.3 Model source code and scripts August 27, 2019 14 MB None
CMAQv5.2 DDM-3D source code and scripts Sept 29, 2017 16 MB None

WRF4.1.1-CMAQ5.3 Coupled Model building scripts 

August 27, 2019 384 KB

CMAQv5.3 Model, WRF4.1.1 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.  
  • Input and output data for the CMAQv5.3 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. 
  • Technical support and questions about this release should be directed to Help Desk at CMAS. Exit