DOI: 10.15139/s3/bdlbtw
title: CMAQ Model Version 5.5 CRACMM2 Input Data (2022r1) - 12/22/2021 - 12/31/2022 12km CONUS

description: &lt;h2&gt;Data Summary&lt;/h2&gt;&lt;p&gt;CMAQv5.5/CMAQv6.0 input data for the &lt;strong&gt;CRACMM2&lt;/strong&gt; chemical mechanism for a 12/22/2021 - 12/31/2022 simulation over the Continental US. &lt;br&gt; 
&lt;br&gt;
&lt;strong&gt;Note:&lt;/strong&gt; The datasets are part of the CMAS Center Amazon Web Services (AWS) Open Data Program and are saved in an &lt;a href=https://aws.amazon.com/pm/serv-s3/&gt;AWS S3 bucket&lt;/a&gt;. The metadata associated with this DOI contain the link to the S3 bucket and instructions for downloading the data.
description: &lt;h2&gt;File Location and Download Instructions&lt;/h2&gt;

&lt;ul&gt; &lt;li&gt;&lt;strong&gt;&lt;a href=https://cmaq-12us1-cracmm2-modeling-platform-2022.s3.amazonaws.com/index.html&gt;Link to emissions, initial, and boundary conditions input files&lt;/a&gt;&lt;/strong&gt; for 2022 12US1 CRACMM2&lt;/li&gt;
&lt;br&gt;
&lt;li&gt; &lt;strong&gt;&lt;a href=https://cmaq-12us1-cracmm2-modeling-platform-2022.s3.amazonaws.com/readme.html&gt;Link to download instructions&lt;/a&gt;&lt;/strong&gt; &lt;/li&gt; 
&lt;/ul&gt;

This S3 bucket contains CMAQ-ready emissions, initial, and boundary conditions input files suitable for running a simulation using the CRACMM2 chemical mechanism. &lt;br&gt;
&lt;ul&gt;
&lt;li&gt;Model-ready emissions inputs using CRACMM2 speciation and files linking representative day emissions to specific calendar days are located under &lt;br&gt;
2022_12US1/emis/cracmmv2_20241031/ and 2022_12US1/emis/emis_dates/&lt;br&gt;&lt;/li&gt;
&lt;li&gt;Boundary conditions files are located under 2022_12US1/icbc/CMAQv54_2022_108NHEMI_STAGE_CRACCM2_FROM_CB6R5M/&lt;br&gt;
An initial conditions file for December 22, 2021 is located under 2022_12US1/icbc/&lt;/li&gt;
&lt;/ul&gt;
&lt;br&gt;

&lt;h2&gt;Meteorology Inputs&lt;/h2&gt;
The meteorology used in processing these emissions and suitable for running CMAQv5.5 can be found at &lt;a href="https://registry.opendata.aws/epa-2022-modeling-platform/"&gt;https://registry.opendata.aws/epa-2022-modeling-platform/&lt;/a&gt; &lt;br&gt;

&lt;h2&gt;Emissions Inputs&lt;/h2&gt;
2022 CRACMMv2 2022v1 (2022hc) emissions (labeled '2022r1') largely follow the &lt;a href="https://www.epa.gov/air-emissions-modeling/2022v1-emissions-modeling-platform"&gt;2022 modeling platform inventory methods&lt;/a&gt; used to generate the data available from this &lt;a href="https://registry.opendata.aws/epa-2022-modeling-platform/"&gt;AWS S3 bucket&lt;/a&gt; except for CRACMMv2 speciation (&lt;a href="https://doi.org/10.5194/acp-24-12903-2024"&gt;Skipper et al., 2024&lt;/a&gt;). Mobile emissions have been further updated to follow &lt;a href="https://acp.copernicus.org/articles/23/13469/2023/"&gt;Murphy et al. 2023&lt;/a&gt;. &lt;br&gt;
&lt;br&gt;
In addition, and new to CRACMM2, CRACMM2 changes how emissions inventories of primary organic aerosol (POA) are allocated to model species of different volatility and functionality. In CRACMM2, POA emissions are assigned to CRACMM species in S2S-Tool+SMOKE and present in the CMAQ-ready files with CRACMM names. The POA inventory is aligned with species of saturation concentrations of 100 µg/m3 and below as described by &lt;a href="https://doi.org/10.26434/chemrxiv-2025-fx8f1"&gt;Pye et al. (2025)&lt;/a&gt;. DESID should not be used to apply POA volatility profiles to emissions as they have already been applied upstream. &lt;br&gt;
&lt;br&gt;
However, in the case of the residential wood combustion files included in this dataset, an additional adjustment (not available at the time of CRACMM2 nor when these emissions were created) is recommended at runtime in DESID. See the “Scale Fire ROC Emissions to account for organic compound volatility” section in the CMAQv5.5 CMAQ_Control_DESID_cracmm2_2022r1.nml namelist file for further details. These files are located under the &lt;code&gt;scripts&lt;/code&gt; directory. 


&lt;h2&gt;Boundary and Initial Conditions Inputs for 12US1 CMAQ CRACMM2 Simulation&lt;/h2&gt;
Hourly values from a simulation over the Northern Hemisphere performed with a modified version of CMAQv5.4 using the CB6R5M_AE7_AQ mechanism updated to include aerosol nitrate photolysis as described in &lt;a href="https://www.sciencedirect.com/science/article/pii/S0048969724005412"&gt;Sarwar et al. (2024)&lt;/a&gt;. Mapping of CB6R5M_AE7_AQ to CRACMM2 mechanism species was performed using &lt;a href="https://github.com/USEPA/CMAQ/blob/main/PREP/bcon/map2mech/SpecDef_cracmm2_derived_from_cb6r5m_ae7_aq.txt"&gt;this file&lt;/a&gt; provided in the CMAQ github code repository. The following is a list of input files and science options used in these hemispheric CMAQ simulations.&lt;br&gt;
&lt;ul&gt;
&lt;li&gt;No bi-directional NH3 air-surface exchange&lt;/li&gt; 
&lt;li&gt;STAGE module for dry deposition&lt;/li&gt; 
&lt;li&gt;Online windblown dust module turned on&lt;/li&gt; 
&lt;li&gt;Chemical mechanism: cb6r5m updated to include aerosol nitrate photolysis as described in &lt;a href="https://www.sciencedirect.com/science/article/pii/S0048969724005412"&gt;Sarwar et al. (2024)&lt;/a&gt;&lt;/li&gt; 
&lt;li&gt;Aerosol module: aero7&lt;/li&gt; 
&lt;li&gt;Domain: Northern Hemisphere using a 108 km grid size and Polar Stereographic projection assuming a spherical earth with radius 6370.0 km.&lt;/li&gt; 
&lt;li&gt;Vertical Resolution: 44 layers from the surface to 50 mb &lt;/li&gt; 
&lt;li&gt;Meteorological fields: WRF4.4.1 &lt;/li&gt; 
&lt;li&gt;Emissions: 2019 HTAP v3.0 anthropogenic emissions + GEIA lightning NO + CAMS biogenic VOC + CAMS soil NO. &lt;/li&gt; 
&lt;li&gt;Initial conditions for December 22, 2021 and hourly boundary conditions for the December 22 – 31, 2021 spin-up period were generated from a 36 km simulation over North America performed with CMAQv5.4 using the CB6R5_AE7_AQ mechanism. Mapping of CB6R5_AE7_AQ to CRACMM2 mechanism species was performed using the same approach as described above for CB6R5M_AE7_AQ but removing the species specific to detailed marine chemistry. &lt;/li&gt; &lt;/ul&gt;

&lt;h2&gt;Additional required inputs for CMAQ&lt;/h2&gt;&lt;br&gt;
In addition to these meteorology, emissions, initial, and boundary conditions files, users will also need certain other mechanism and time independent input files to perform a 2022 12US1 simulation of CMAQv5.5 using CRACMM2. The following files are included with this 2022 data repository:&lt;br&gt;
&lt;br&gt;
&lt;ul&gt;
&lt;li&gt; GRIDDESC grid description file for the 12US1 domain &lt;/li&gt; 
&lt;li&gt; 12US1 grid mask file for US states (can be used with DESID or ISAM)&lt;/li&gt; 
&lt;li&gt; Gridded normalized biogenic emission factors for running with inline BEISv4 &lt;/li&gt; 
&lt;li&gt; EPIC files needed when running with bi-directionaly NH3 air-surface exchange&lt;/li&gt; 
&lt;li&gt; Lighting NO files based on lightning data from WWLLN&lt;/li&gt; 
&lt;li&gt; Land surface files needed for running with inline biogenics from MEGAN&lt;/li&gt; 
&lt;li&gt; Ocean files (needed for sea spray emissions) &lt;/li&gt; &lt;/ul&gt;
&lt;br&gt;

&lt;h2&gt;Scripts and control files&lt;/h2&gt;
&lt;ul&gt;
&lt;li&gt;&lt;a href="https://cmaq-12us1-cracmm2-modeling-platform-2022.s3.amazonaws.com/index.html#2022_12US1/scripts/v55/"&gt;Example run script and CMAQ Control DESID file for running CMAQv5.5 with these 2022 input files.&lt;/a&gt; &lt;/li&gt; &lt;/ul&gt;

&lt;h2&gt;Resources for setting up a CMAQ simulation&lt;/h2&gt;
&lt;a href="https://github.com/USEPA/CMAQ/blob/main/DOCS/Users_Guide/Tutorials/CMAQ_UG_tutorial_benchmark_cracmm2_stage.md"&gt;CMAQ benchmark tutorial for CRACMM2:&lt;/a&gt; describes how to prepare your Linux system for installing and running CMAQ.

&lt;h2&gt;File Format&lt;/h2&gt;&lt;br&gt;
The 2022 model inputs are stored as uncompressed netcdf formatted files using &lt;a href="https://www.cmascenter.org/ioapi/"&gt;I/O API data structures&lt;/a&gt;. Information on the model projection and grid structure is contained in the header information of the netcdf files. The netcdf files can be opened and manipulated using I/O API utilities (e.g. M3XTRACT, M3WNDW) or other software programs that can read and write netcdf formatted files (e.g. Fortran, R, Python).&lt;br&gt;


&lt;h2&gt;CRACMM2 emissions are compatible with the CRACMM1 mechanism&lt;/h2&gt;&lt;br&gt;
&lt;br&gt;Using these emissions in CRACMM1 requires minor adjustments following this guidance: &lt;a href="https://usepa.github.io/CRACMM/emissions/README.html"&gt;https://usepa.github.io/CRACMM/emissions/README.html&lt;/a&gt;&lt;br&gt;
description: &lt;h2&gt;Recommended citations&lt;/h2&gt;
For traceability, please cite use of these inputs with the dataset doi of &lt;a href="https://doi.org/10.15139/S3/BDLBTW"&gt;https://doi.org/10.15139/S3/BDLBTW&lt;/a&gt;. For method documentation, please cite at least one of the following CMAQ-CRACMM publications that best matches your usage of the data: &lt;br&gt;
&lt;br&gt;
 &lt;a href="https://doi.org/10.5194/acp-23-5043-2023"&gt;Pye et al. (2023)&lt;/a&gt;: Overall CRACMM approach for chemistry and emissions.&lt;br&gt;

&lt;br&gt; &lt;a href="https://doi.org/10.5194/acp-24-12903-2024"&gt;Skipper et al. (2024)&lt;/a&gt;: CRACMM version 2, updated gas-phase emissions mapping rules for select species (see &lt;a href="https://github.com/USEPA/CRACMM/blob/main/emissions/cracmm2/cracmm2_mapping_flowchart.pdf"&lt;cracmm2_mapping_flowchart.pdf&lt;/a&gt;, formaldehyde.&lt;br&gt;

&lt;br&gt;&lt;a href="https://doi.org/10.26434/chemrxiv-2025-fx8f1"&gt;Pye et al. (2025)&lt;/a&gt;: CRACMM 2 POA mapping to volatility and O:C species.
description: Disclaimer: This data product has been reviewed in accordance with U.S. Environmental Protection Agency policy and approved for public release. At the time of release, the data had not yet been published in peer-reviewed literature. The data is provided for research and the user should verify the data is suitable for their intended use.