A better representation of volatile organic compound chemistry in WRF-Chem and its impact on ozone over Los Angeles
- Creators
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Zhu, Qindan1, 2
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Schwantes, Rebecca H.
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Coggon, Matthew
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Harkins, Colin1
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Schnell, Jordan1, 3
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He, Jian1
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Pye, Havala O. T.4
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Li, Meng1
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Baker, Barry5
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Moon, Zachary5, 6
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Ahmadov, Ravan3
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Pfannerstill, Eva Y.7, 8
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Place, Bryan4
- Wooldridge, Paul7
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Schulze, Benjamin C.9
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Arata, Caleb7
- Bucholtz, Anthony10
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Seinfeld, John H.9
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Warneke, Carsten
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Stockwell, Chelsea E.
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Xu, Lu1, 11
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Zuraski, Kristen1
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Robinson, Michael A.1
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Neuman, J. Andrew
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Veres, Patrick R.12
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Peischl, Jeff1
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Brown, Steven S.13
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Goldstein, Allen H.7
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Cohen, Ronald C.7
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McDonald, Brian C.
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1.
Cooperative Institute for Research in Environmental Sciences
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2.
Massachusetts Institute of Technology
- 3. NOAA Global Systems Laboratory, Boulder, CO 80305, USA
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4.
Environmental Protection Agency
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5.
Air Resources Laboratory
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6.
Earth Resources Technology (United States)
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7.
University of California, Berkeley
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8.
Forschungszentrum Jülich
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9.
California Institute of Technology
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10.
Naval Postgraduate School
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11.
Washington University in St. Louis
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12.
National Center for Atmospheric Research
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13.
University of Colorado Boulder
Abstract
The declining trend in vehicle emissions has underscored the growing significance of volatile organic compound (VOC) emissions from volatile chemical products (VCPs). However, accurately representing VOC chemistry in simplified chemical mechanisms remains challenging due to its chemical complexity including speciation and reactivity. Previous studies have predominantly focused on VOCs from fossil fuel sources, leading to an underrepresentation of VOC chemistry from VCP sources. We developed an integrated chemical mechanism, RACM2B-VCP, that is compatible with WRF-Chem and is aimed at enhancing the representation of VOC chemistry, particularly from VCP sources, within the present urban environment. Evaluation against the Air Quality System (AQS) network data demonstrates that our model configured with RACM2B-VCP reproduces both the magnitude and spatial variability of O3 and PM2.5 in Los Angeles. Furthermore, evaluation against comprehensive measurements of O3 and PM2.5 precursors from the Reevaluating the Chemistry of Air Pollutants in California (RECAP-CA) airborne campaign and the Southwest Urban NOx and VOC Experiment (SUNVEx) ground site and mobile laboratory campaign confirm the model's accuracy in representing NOx and many VOCs and highlight remaining biases. Although there exists an underprediction in the total VOC reactivity of observed VOC species, our model with RACM2B-VCP exhibits good agreement for VOC markers emitted from different sectors, including biogenic, fossil fuel, and VCP sources. Through sensitivity analyses, we probe the contributions of VCP and fossil fuel emissions to total VOC reactivity and O3. Our results reveal that 52 % of the VOC reactivity and 35 % of the local enhancement of MDA8 O3 arise from anthropogenic VOC emissions in Los Angeles. Significantly, over 50 % of this anthropogenic fraction of either VOC reactivity or O3 is attributed to VCP emissions. The RACM2B-VCP mechanism created, described, and evaluated in this work is ideally suited for accurately representing ozone for the right reasons in the present urban environment where mobile, biogenic, and VCP VOCs are all important contributors to ozone formation.
Copyright and License
© Author(s) 2024. This work is distributed under the Creative Commons Attribution 4.0 License.
Published by Copernicus Publications on behalf of the European Geosciences Union.
Acknowledgement
Qindan Zhu was supported by funding from the EPA STAR program and the NOAA Climate and Global Change Postdoctoral Fellowship. This RECAP field campaign was partially funded by the Presidential Early Career Award for Scientists and Engineers (PECASE) (from Brian McDonald). Eva Y. Pfannerstill was funded by a Feodor Lynen Research Fellowship from the Alexander von Humboldt Foundation. We thank Andrew Rollins for helpful discussions on the SUNVEx NOx measurements. We also thank NOAA's High Performance Computing and Communications (HPCC) program.
Funding
This research has been supported by the U.S. Environmental Protection Agency (grant no. 84001001) and the California Air Resources Board (grant nos. 20RD003 and 20AQP012). This work has been partly supported by the NOAA Cooperative Agreement with CIRES (grant nos. NA17OAR4320101 and NA22OAR4320151). Matthew Coggon, Colin Harkins, Jordan Schnell, Jian He, Meng Li, Chelsea E. Stockwell, Lu Xu, Kristen Zuraski, Michael A. Robinson, J. Andrew Neuman, and Jeff Peischl have been supported in part by NOAA cooperative agreements (grant nos. NA17OAR4320101 and NA22OAR4320151).
Data Availability
The observational data from SUNVEx and RECAP field campaigns and WRF-Chem anthropogenic emission files are available at https://csl.noaa.gov/groups/csl7/measurements/2021sunvex/emissions/ (Harkins and McDonald, 2024). The analysis dataset is available at https://csl.noaa.gov/groups/csl4/modeldata/data/Zhu2023/ (Zhu et al., 2024a). The WRF-Chem source codes and the analysis codes are available at https://github.com/NOAA-CSL/WRF-Chem_CSL_Publications/tree/main/Qindan_Zhu_et_al_2024 (Zhu et al., 2024b).
Supplemental Material
The supplement related to this article is available online at: https://doi.org/10.5194/acp-24-5265-2024-supplement.
Conflict of Interest
At least one of the (co-)authors is a member of the editorial board of Atmospheric Chemistry and Physics. The peer-review process was guided by an independent editor, and the authors also have no other competing interests to declare.
Additional Information
The views expressed in this document are solely those of the authors and do not necessarily reflect those of the U.S. Environmental Protection Agency (EPA). EPA does not endorse any products or commercial services mentioned in this publication. The statements, findings, conclusions, and recommendations are those of the author(s) and do not necessarily reflect the views of NOAA or the U.S. Department of Commerce.
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors.
Additional Information
This paper was edited by Qi Chen and reviewed by two anonymous referees.
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Additional details
- Environmental Protection Agency
- 84001001
- California Air Resources Board
- 20RD003
- California Air Resources Board
- 20AQP012
- National Oceanic and Atmospheric Administration
- NA17OAR4320101
- National Oceanic and Atmospheric Administration
- NA22OAR4320151
- Environmental Protection Agency
- STAR program -
- National Oceanic and Atmospheric Administration
- Climate and Global Change Postdoctoral Fellowship -
- National Science Foundation
- PECASE -
- Alexander von Humboldt Foundation
- Feodor Lynen Research Fellowship -
- Accepted
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2024-03-21
- Caltech groups
- Division of Chemistry and Chemical Engineering (CCE), Division of Geological and Planetary Sciences (GPS)
- Publication Status
- Published