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US EPA Office of Research and Development

The Community Multiscale Air Quality (CMAQ) model is an active open-source development project of the U.S. EPA that consists of a suite of programs for conducting air quality model simulations. CMAQ combines current knowledge in atmospheric science and air quality modeling, multi-processor computing techniques, and an open-source framework to deliver fast, technically sound estimates of ozone, particulates, toxics and acid deposition. 

For further information please visit the EPA website for the CMAQ system:

New features in CMAQ version 5.4 include:

  • Updated chemistry for ozone (O3) and particulate matter (PM) formation from global-to-local scales
  • Introduction of the Community Regional Atmospheric Chemistry Multiphase Model (CRACMM)
  • Biogenic emissions algorithm options have been expanded
  • Revised algorithms for modeling the dry deposition of particles from the atmosphere (M3DRY and STAGE updates)
  • Streamlined building of the coupled WRF-CMAQ system compatible with WRFv4.4+
  • Improved efficiency, accuracy, and user experience for CMAQ instrumented model extensions CMAQ-DDM-3D and CMAQ-ISAM
  • Expansion of emissions diagnostic output features
  • Introduction of a domain-wide Budget Reporting tool
  • Online integration of common pollutant post-processing tasks (i.e. output total PM2.5 mass and more directly!)
  • Community Contribution: Incorporation of the Two-Dimensional Volatility Bases Set (2D-VBS) chemical mechanism
  • See the full list of CMAQv5.4 updates on our new CMAQ Wiki page. CMAQv5.4 Updates


For up-to-date documentation, source code, and sample run scripts, please clone or download the CMAQ git repository available through GitHub:
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