An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Community Multiscale Air Quality Modeling System (CMAQ)

CMAQ Documentation

CMAQ can be customized to fit your research needs. Below are several types of CMAQ documentation designed for both new and veteran users of CMAQ. 

Release Notes 

Release notes for each CMAQ version are provided to outline the specific changes that were made to the modeling system since the previous release.  Click on the links below to view the selected version's release notes.

The following links exit the site Exit

CMAQ User's Guide

A comprehensive set of instructions for model users that covers:

  • Overview of science in the CMAQ modeling system
  • System requirements and installation
  • Description of CMAQ programs, input and output files
  • Directions for defining grids, layers, domains and chemistry
  • Description of configuration options for CMAQ science options
  • Directions for using CMAQ instrumented models
  • Directions for customizing emissions processing
  • Analysis tools for CMAQ
  • Tips on creating CMAQ geospatial data inputs
  • An introduction to the parallel implementaiton CMAQ for increased computational efficiency
  • Tips on configuring the Weather Research and Forecasting Model (WRF) for use with air quality models 

The following links exit the site Exit

Tutorials for Common Tasks 

Step-by-step directions to help you get started with various tasks within the CMAQ system including:

  • How to run the CMAQ test case
  • How to run the CMAQ-ISAM test case (New with v5.3.2 release!)
  • Buildig WRF-CMAQ for GNU (New with v5.3.2 release!)
  • How to modify a chemical mechanism in CMAQ (New with v5.3.2 release!)
  • How to build CMAQ using the GNU compiler
  • How to build CMAQ using the Intel compiler
  • How to debug issues issues encountered when installing and running the CMAQ test case.
  • How to prescribe emissions using the DESID module
  • How to create an ocean file
  • How to add chemically inert tracers to the CMAQ model
  • How to creat Initial and Boundary Conditions files from seasonal average Hemispheric CMAQ output

View CMAQ tutorials.Exit

We hope to add more tutorials over time.  We welcome suggestions for new tutorials for specific tasks.  Click on the "Contact Us" link at the top or bottom of the page to submit your idea. 

CMAQ Science Document

The original CMAQ Science Document (dated March 1999) contains chapters that address specific scientific and technical issues involved in the development and application of the CMAQ system. Collectively, it provides the scientific basis and point of reference for the state of the science captured in the June 1998 initial release of CMAQ. 

View the documentation for CMAQ's original science alrgorithms. Exit

EPA SIP Modeling Guidance

The Air Quality Modeling Group within the Office of Air Quality Planning and Standards provides technical guidance to states on how to conduct modeling as part of State Implementation Plan (SIP) demonstrations for O3, PM2.5 and regional haze.