Community Regional Atmospheric Chemistry Multiphase Mechanism
Havala Pye, pye.havala@epa.gov
The Community Regional Atmospheric Chemistry Multiphase Mechanism (CRACMM) is a description of atmospheric NOX-VOC-O3-aerosol chemistry and associated metadata (Pye et al., 2023; Place et al., 2023). CRACMM is available in the EPA Community Multiscale Air Quality (CMAQ) modeling system starting with version 5.4 (2022 release). In CMAQ, CRACMM was initially released as CRACMM1 and CRACMM1AMORE which only differ in the representation of isoprene chemistry (see Wiser et al., 2023). For more information about the plans for CRACMM, see the EPA fact sheet on the CMAQ website. The main repository branch on github will continually evolve and periodically tagged to reflect official release versions. To obtain frozen versions of CRACMM, select the appropriate branch on github and/or tag.
The official, frozen versions of CRACMM reside in CMAQ in the US EPA Github repository. Here, we bring together CRACMM metadata from across CMAQ and provide additional information such as how to map emissions to the mechanism. This information is intended to support CMAQ users and provide the atmospheric chemistry community with information about CRACMM. This repository is organized as follows:
- Chemistry: the mechanism in CMAQ-ready and markdown formats
- Emissions: inputs and outputs to emission mapping tools and code to perform mapping of individual species to CRACMM (informed by Foley et al., 2023)
- Metadata: information about CRACMM species (molecular weights, volatility, solubility, representative structures, etc.)
- Utilities: python code to assemble metadata from CMAQ code and routines for screening level predictions of organic aerosol and ozone formation potential
Foley, K. M., Pouliot, G. A., Eyth, A., Aldridge, M. F., Allen, C., Appel, K. W., Bash, J. O., Beardsley, M., Beidler, J., Choi, D., Farkas, C., Gilliam, R. C., Godfrey, J., Henderson, B. H., Hogrefe, C., Koplitz, S. N., Mason, R., Mathur, R., Misenis, C., Possiel, N., Pye, H. O. T., Reynolds, L., Roark, M., Roberts, S., Schwede, D. B., Seltzer, K. M., Sonntag, D., Talgo, K., Toro, C., Vukovich, J., Xing, J., and Adams, E.: 2002–2017 anthropogenic emissions data for air quality modeling over the United States, Data in Brief, 47, 109022, https://doi.org/10.1016/j.dib.2023.109022, 2023.
Place, B. K., Hutzell, W. T., Appel, K. W., Farrell, S., Valin, L., Murphy, B. N., Seltzer, K. M., Sarwar, G., Allen, C., Piletic, I. R., D'Ambro, E. L., Saunders, E., Simon, H., Torres-Vasquez, A., Pleim, J., Schwantes, R. H., Coggon, M. M., Xu, L., Stockwell, W. R., and Pye, H. O. T.: Sensitivity of northeastern US surface ozone predictions to the representation of atmospheric chemistry in the Community Regional Atmospheric Chemistry Multiphase Mechanism (CRACMMv1.0), Atmos. Chem. Phys., 23, 9173–9190, https://doi.org/10.5194/acp-23-9173-2023, 2023.
Pye, H. O. T., Place, B. K., Murphy, B. N., Seltzer, K. M., D'Ambro, E. L., Allen, C., Piletic, I. R., Farrell, S., Schwantes, R. H., Coggon, M. M., Saunders, E., Xu, L., Sarwar, G., Hutzell, W. T., Foley, K. M., Pouliot, G., Bash, J., and Stockwell, W. R.: Linking gas, particulate, and toxic endpoints to air emissions in the Community Regional Atmospheric Chemistry Multiphase Mechanism (CRACMM), Atmos. Chem. Phys., 23, 5043–5099, https://doi.org/10.5194/acp-23-5043-2023, 2023.
Vannucci, P. F., Foley, K., Murphy, B. N., Hogrefe, C., Cohen, R. C., and Pye, H. O. T.: Temperature-Dependent Composition of Summertime PM2.5 in Observations and Model Predictions across the Eastern U.S, ACS Earth Space Chem., [https://doi.org/10.1021/acsearthspacechem.3c00333], 2024.
Wiser, F., Place, B. K., Sen, S., Pye, H. O. T., Yang, B., Westervelt, D. M., Henze, D. K., Fiore, A. M., and McNeill, V. F.: AMORE-Isoprene v1.0: a new reduced mechanism for gas-phase isoprene oxidation, Geosci. Model Dev., 16, 1801–1821, https://doi.org/10.5194/gmd-16-1801-2023, 2023.
- Collecting updates leading to CRACMM2
- Final version for release in CMAQv5.4
- ROCALK names updated
- Renamed HC8 to HC10
- Renamed ROCN/P series to ROCN/PALK
- Synced with latest CMAQ version of chemistry and metadata
- Renamed toluene surrogate (explicit) to TOL
- Added flowchart
- Renamed XYOP to XYE to avoid overlap with name of existing peroxy radical.
- This version used to create initial SMOKE inputs.
- Known issues:
- XYOP emitted species name overlaps with a peroxy radical in RACM2. XYOP renamed to XYE (major contributors are o-xylene and ethylbenzene).
- TOLUENE named to TOL in later versions.
- Date: 20210812. Updated carbons (Speciation Tool input) for missing species.
- Date: 20210806. Updated Misc Silanes surrogate and removed non-ROC species from mech4import.
- Date: 20210805. Mineral oil surrogate changed from decane to linoleic acid (mapping changed from HC8 to ROCP1). 8 new SPECIATE species added.
Date: 20210716
- PAH eliminated. The most abundant species that was in PAH fit better in the existing oxygenated aromatics. When PAHs were defined with O:C=0, very little mass was left.
- NAPH includes small amounts of O:C=0 PAHs.
- Propylene glycol (and potential one other species) is now explicit as PROG.
- FURAN has been fully implemented as a species.
- S/IVOCs are now called ROC species. IVOCOXY is now ROCIOXY.
- SVOC ROC binning now occurs before single-ring aromatic mapping.
- ROCP4ARO was eliminated due to lack of significant emissions and OA potential.
- Glycoaldehyde was moved from ALD to GLY to better represent its solubility.
- Silanes and siloxanes of any volatility are ROCIOXY.
- UNKCRACMM is now used for non-carbon-containing species and elemental carbon (and TC).
- DIEN has been deleted. Small amount of anthropogenic dienes appear in FURAN. BDE13 is the major anthropogenic diene and already explicit.
- Some representative compounds (SPECIATE) have been updated: OC, NCOM, POC, PNCOM.
- Date: 20210702. Added IVOCOXY to mapper; updated representative compounds for IVOCP6ARO, SVOCN1, and SVOCP0 in SPECIATE.
- Date: 20210621. initial mapper and species properties for CRACMM.
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