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IAMA 2021 Conference: Integrating reactive organic carbon emissions into the Community Regional Atmospheric Chemistry Multiphase Mechanism (CRACMM)
Citation:
Pye, H., K. Seltzer, B. Murphy, C. Allen, I. Piletic, E. D'Ambro, R. Schwantes, M. Coggon, E. Saunders, S. Farrell, K. Foley, G. Pouliot, AND W. Stockwell. IAMA 2021 Conference: Integrating reactive organic carbon emissions into the Community Regional Atmospheric Chemistry Multiphase Mechanism (CRACMM). International Aerosol Modeling Algorithms, Davis, California, December 08 - 10, 2021.
Impact/Purpose:
The chemical mechanism of an atmospheric chemical transport model like the Community Multiscale Air Quality (CMAQ) system contains a condensed set of reactions that describe the interactions between emitted organic compounds and nitrogen oxides as well their reaction products. The Community Regional Atmospheric Chemistry Multiphase Mechanism (CRACMM) builds on the history of the Regional Atmospheric Chemistry Mechanism, Version 2 (RACM2) and aims to couple gas- and particle-phase chemistry by treating the entire pool of atmospheric reactive organic carbon (ROC) relevant to present-day emissions. Here, we develop CRACMM species to represent the total emissions of ROC.
Description:
The chemical mechanism of an atmospheric chemical transport model like the Community Multiscale Air Quality (CMAQ) system contains a condensed set of reactions that describe the interactions between emitted organic compounds and nitrogen oxides as well their reaction products. The Community Regional Atmospheric Chemistry Multiphase Mechanism (CRACMM) builds on the history of the Regional Atmospheric Chemistry Mechanism, Version 2 (RACM2) and aims to couple gas- and particle-phase chemistry by treating the entire pool of atmospheric reactive organic carbon (ROC) relevant to present-day emissions. Here, we develop CRACMM species to represent the total emissions of ROC, considering the OH reactivity, ability to form ozone and secondary organic aerosol (SOA), and other properties of individual emitted compounds. Compared to RACM2, we reduce the number of traditional volatile organic carbon species and increase the number of oxygenated and semivolatile to intermediate volatility precursors in the mechanism. In addition, we add explicit hazardous air pollutants to better characterize exposures relevant for human health. We contrast emissions of ROC in 2002 and 2017 from the EPA’s Air QUAlity TimE Series project and their treatment in CRACMM to illustrate how precursors to ozone, SOA, and other endpoints are expected to propagate through the system. The CRACMM mechanism species will be operationalized in chemical transport models in future work.
