Welcome to CMAQ-Model.org

This is the official CMAQ website hosted by the Community Modeling and Analysis System (CMAS) Center at the University of North Carolina at Chapel Hill . CMAQ is an active open-source development project of the U.S. EPA Atmospheric Science Modeling Division that consists of a suite of programs for conducting air quality model simulations. CMAQ is supported and distributed by the CMAS Center.

Partners

Institute for the Environment

CMAS Center

U.S. EPA ASMD

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CMAQ 5.0

Simulate multiple tropospheric air quality issues at once using this highly optimized, state-of-the-science suite of modeling software

• Download CMAQv5.0 and MCIPv4.0
• CMAQv5.0 Technical Documentation and Release Notes
• MCIPv4.0 Release Notes
• CMAQv5.0 Users Manual

CMAQ combines current knowledge in atmospheric science and air quality modeling with multi-processor computing techniques in an open-source framework to deliver fast, technically sound estimates of ozone, particulates, toxics, and acid deposition.

Features of CMAQ5.0

• Aerosols

  • AERO6: 6th generation CMAQ aerosol module
  • PMFINE split into 9 new species
  • ISORROPIA2 for aerosol thermodynamics
  • Primary organic aerosol aging
  • In-line windblown dust model
  • Updated SOA yield parameterization

• Gas-phase Chemistry

  • CB05 with updated toluene chemistry
  • Addition of SAPRC-07 mechanism option
  • Updates to the in-line photolysis module

• Clouds

  • CCTM cloud module was updated to simulate subgrid clouds only when the meteorological driver uses a convective cloud parameterization

• Vertical Diffusion

  • Default read of C-staggered wind components from MET_DOT_3D
  • Corrected component-wise shear to properly use B-staggered winds
  • Modified eddy diffusivity for stable conditions
  • Reduced the minimum eddy diffusivity from 0.5 m²/s to 0.01 m²/s, and from 2.0 m²/s to 1.0 m²/s for urban areas

• Vertical Advection

  • A new method for computing the vertical velocity has been implemented that follows the omega calculation in WRF but uses CMAQ’s advection schemes (PPM) to compute horizontal mass divergence

• Lightning NOx

  • In-line and off-line lightning NOx options can estimate the air quality impacts of lightning NOx emissions through the tropospheric column.

•  Dry Deposition

  • Bidirectional exchange of NH₃
  • Mesophyll resistance added to the CCTM dry deposition routine m3dry
  • NO₂ deposition velocity updates
  • MOSAIC: Run-time option for output of land-use-specific deposition velocity and flux

• Multipollutant Modeling

  • Includes multipollutant chemical mechanisms and species for gas, aqueous, aerosols, air toxics, mercury, and sea salt
  • Bidirectional exchange of Hg⁰

• Two-way Coupled WRF3.3 and CMAQv5.0

  • Simulated aerosols from CCTM provide direct feedback to the WRF radiation calculations

MCIP version 4.0

The meteorology-chemistry interface processor converts MM5 and WRF output to CMAQ and SMOKE-compatible format.

Download the MCIP version 4.0 from the CMAS Center to take advantage of the latest updates to the program.