US EPA Community Multiscale Air Quality Model (CMAQ) Website: https://www.epa.gov/cmaq
CMAQ is an active open-source development project of the U.S. EPA's Office of Research and Development that consists of a suite of programs for conducting air quality model simulations. CMAQ is supported by the CMAS Center: http://www.cmascenter.org
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.
A bug was identified within the CMAQ to WRF coupling routine (twoway_feedback.F90) where aerosol feedback information is transferred from CMAQ to WRF. In doing so, it was found that WRF was not receiving the correct aerosol feedback information due to a looping error relating to the number of layers set to 1 in some cases. The bug impacts the WRF-CMAQ coupled system in the CMAQv5.3 release series (v5.3, v5.3.1, v5.3.2, v5.3.3) when running with short wave radiative feedback. The bug was not present in prior WRF-CMAQ versions. The bugfix in CMAQv5.4 now correctly captures the variations in the aerosol optical properties and consequently the direct feedback effects through all layers. Users of WRF-CMAQ are strongly encouraged to update to CMAQv5.4.
This CMAQ Git archive is organized with each official public release stored as a branch on the main USEPA/CMAQ repository. The most recently released version of the the model will always be on the branch called 'main'. To clone code from the CMAQ Git archive, specify the branch (i.e. version number) and issue the following command from within a working directory on your server:
git clone -b main https://github.com/USEPA/CMAQ.git CMAQ_REPO
Users who wish to adopt the most recent bugfixes or minor updates to v5.4 should review the tagged versions of v5.4+:
Record of changes to CMAQv5.4
To clone code with all of the CMAQv5.4 bug fixes issue the following command from within a working directory on your server:
git clone -b CMAQv5.4.0.4_5Sept2024 https://github.com/USEPA/CMAQ.git CMAQ_5.4.0.5
Source code and scripts are organized as follows:
Code documentation is included within this repository (they are version-controlled along with the code itself).
Benchmark/tutorial data for the CMAQv5.4 release are available from the CMAS Data Warehouse. The input and output files are stored on Google Drive and on Amazon Web Services (AWS) Open Data Registry. CMAQv5.4 comes with new input and output benchmark data for July 1-2, 2018 over the Northeast US (links provided below). Tutorials are provided for using the benchmark data to test running of the base CMAQ model, WRF-CMAQ, CMAQ-ISAM, and CMAQ-DDM-3D. The input datasets include a grid mask file for the United States (GRIDMASK_STATES_12SE1.nc). The grid mask file is used for running the new ISAM and DDM-3D test cases, or to test out regional emissions scaling with DESID. The input datasets also include an ocean file with new variables needed to use the cb6r5_ae7 and cb6r5m_ae7 mechanisms. See the Ocean File tutorial for more information on changes to the required ocean file input in v5.4.
In addition, a full set of inputs for 2018 are provided for the 12US1 domain (299 column x 459 row x 35 layer, 12-km horizontal grid spacing) on AWS, including emissions compatible with both the CB6r5 and CRACMM chemical mechanisms. Note that the 12US1 inputs are netCDF-4/HDF5 compressed files to substantially reduce file sizes. Through testing at the EPA, we’ve noticed that certain domains encounter model crashes from reading in large amounts of compressed netCDF data. A work around for those cases is uncompressing the data manually via nccopy 1 or m3cple (compiled with HDF5) before running the CMAQ simulation.
CMAQ Version | Data Type (Size) | Domain | Simulation Dates | Data Access |
---|---|---|---|---|
v5.4 CB6 | Input (10.3 Gb) | Northeast US | July 1 - 2, 2018 | Metadata, DOI, and download instructions Google Drive Link AWS Link |
v5.4 CB6 | Output (13.9 Gb) | Northeast US | July 1 - 2, 2018 | Metadata, DOI, and download instructions Google Drive Link AWS Link |
v5.4 CB6 | Input | 12US1 | Jan 1 - Dec 31, 2018 | Metadata, DOI, and links to data on AWS |
v5.4 CRACMM | Input | 12US1 | Jan 1 - Dec 31, 2018 | Metadata, DOI, and links to data on AWS |
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