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  2. Community Multiscale Air Quality Modeling System (CMAQ)

Download Data

CMAQ belongs to the Eulerian class of mathematical models, tracking the movement of pollution plumes over time on a fixed three-dimensional grid. CMAQ simulates hourly concentration and deposition for a large number of chemical species for multiple vertical layers, from the earth's surface (the air we breathe) up to the tropopause where pollutants are transported across the globe. CMAQ output represents volume-average pollutant concentrations for every grid cell and vertical layer in the model domain. 

A year-long simulation of CMAQ over the U.S. can produce up to 45 terabytes of data. Because CMAQ input and output data are so large they are stored as binary files using Network Common Data Form (netCDF). CMAQ data can be visualized using various tools (e.g., VERDI, Paraview, Vapor, R, Matlab, etc.). The data can also be summarized spatially to represent values for a census tract or watershed or it can be extracted for a specific location. Results from some of EPA's modeling efforts are provided for download and visualization. 

What does CMAQ output look like? This interactive map tool can be used to view hourly surface-level estimates over the U.S. for ozone or PM2.5 for any month in 2012. Model-estimated wind speed and direction are also included to show how the model simulates the movement of air pollution from the pollution sources to downwind locations. This website can be used to explore how ozone and PM2.5 levels change throughout the day, for example morning versus afternoon levels, and throughout different seasons. 

  • View the animated visualization of CMAQ predicted ozone and PM2.5.

Download CMAQ data

Download CMAQ output from previous experiments, and inputs to create new simulations.


 
 

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Test Cases

Download test case data and instructions as well as additional model inputs.


 
 


 
 

EPA'S Air Quality Time Series (EQUATES) Project

Lean more about the EQUATES project and how data from this experiment can be used. 

Community Multiscale Air Quality Modeling System (CMAQ)

  • Learn About CMAQ
    • CMAQ's Purpose
    • CMAQ 25th Anniversary
    • Overview of Science Processes
    • Browse CMAQ Applications
  • CMAQ Models
    • CMAQ-ISAM
    • CMAQ-DDM-3D
    • WRF-CMAQ
    • MPAS-CMAQ
  • Download CMAQ
    • Model Source Code
    • Documentation
    • Resources/Utilities for Model Users
  • CMAQ Research
    • Research Highlights
    • CRACMM
    • How to Cite CMAQ
    • Publications and Peer Review
  • CMAQ Community
    • CMAQ User Community
    • Opportunities for Collaboration
    • CMAQ Webinars
    • CMAQ Community Survey Results
  • Download Data
    • Download CMAQ data
    • Test Cases
    • EPA'S Air Quality Time Series (EQUATES) Project
  • About Us
  • Frequent Questions
Contact Us about the Community Multiscale Air Quality Modeling System
Contact Us to ask a question, provide feedback, or report a problem.
Last updated on April 11, 2025
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