CMAQ predicts hourly concentration and deposition values for a large number of chemical species for each location in the modeled domain. These results 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 CMAQ predictions over the U.S. for ozone or PM2.5 for any month in 2012. Model-predicted 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.
Download CMAQ Data Files
CMAQ input and output files are hosted on the CMAS Data Warehouse, an open-access database for collecting and disseminating meteorology, emissions and air quality model input and output. Each database entry provides metadata for the modeling dataset, instructions on how to obtain the downloadable data, and a unique DOI, allowing for easy citation and discovery of specific datasets.
Available Model Output Datasets
The following links exit the site
|CMAQ Version||Data Type||Domain||Vertical Layer(s)||Simulation Dates||Dataverse DOI|
|v5.0.2||Hourly and Daily Output for 14 pollutants||Continental US||Layer 1 (surface)||Jan 1 - Dec 31 for years 2002-2012||DOIs are year-specific|
|v5.1||Hourly and Daily Output for 14 pollutants||Continental US||Layer 1 (surface)||Jan 1 - Dec 31, 2013||https://doi.org/10.15139/S3/FQO7IS|
|v5.2||Hourly and Daily Output for 14 pollutants||Continental US||Layer 1 (surface)||Jan 1 - Dec 31, 2014||https://doi.org/10.15139/S3/XYW3HL|
CMAQ output is often combined, or "fused", with observed air quality measurements to remove any consistent model biases prior to using the model predictions for a particular application. Below are examples of bias-corrected CMAQ outputs that are available to download.
Ozone and PM2.5
- The Centers for Disease Control and Prevention (CDC) use spatially fused surfaces of ozone and PM2.5 provided by EPA that combine CMAQ results with ambient monitoring data to inform their National Environmental Public Health Tracking Network. View these fused air quality surfaces for 2002 - 2012 using the CDC Air Quality Data Explorer Tool or download the fused data through the EPA's Remote Sensing Information Gateway (RSIG).
- Shapefiles of CMAQ-predicted values of annual total deposition across the US for 2002 through 2012 are available through our FTP server. These values were created using CMAQ v5.0.2 and include the bidirectional flux of ammonia. Total deposition values are developed by summing the dry and wet deposition in each grid cell. For these shapefiles, the wet deposition component has been bias corrected using measured values from the National Atmospheric Deposition Program (NADP) and precipitation adjusted using the Parameter-elevation Relationships on Independent Sloped Model (PRISM). Additional meta data is provided with the data files.
- The NADP Total Deposition Science Committee (TDEP) has created estimates of total deposition using a measurement-model fusion approach that relies on CMAQ model output and measured values from monitoring networks. For these files, the wet deposition values come from the NADP measurements and the PRISM model. The dry deposition values are from the fusion of CMAQ model values and observed concentration values. These data are provided as ESRI grid files and as image files.