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Ozone production chemistry in the presence of urban plumes

Brune, W. H. and Baier, B. C. and Thomas, J. and Ren, X. and Cohen, R. C. and Pusede, S. E. and Browne, E. C. and Goldstein, A. H. and Gentner, D. R. and Keutsch, F. N. and Thornton, J. A. and Harrold, S. and Lopez-Hilfiker, F. D. and Wennberg, P. O. (2016) Ozone production chemistry in the presence of urban plumes. Faraday Discussions, 189 . pp. 169-189. ISSN 1359-6640. doi:10.1039/C5FD00204D.

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Ozone pollution affects human health, especially in urban areas on hot sunny days. Its basic photochemistry has been known for decades and yet it is still not possible to correctly predict the high ozone levels that are the greatest threat. The CalNex_SJV study in Bakersfield CA in May/June 2010 provided an opportunity to examine ozone photochemistry in an urban area surrounded by agriculture. The measurement suite included hydroxyl (OH), hydroperoxyl (HO_2), and OH reactivity, which are compared with the output of a photochemical box model. While the agreement is generally within combined uncertainties, measured HO2 far exceeds modeled HO_2 in NO_x-rich plumes. OH production and loss do not balance as they should in the morning, and the ozone production calculated with measured HO_2 is a decade greater than that calculated with modeled HO_2 when NO levels are high. Calculated ozone production using measured HO2 is twice that using modeled HO_2, but this difference in calculated ozone production has minimal impact on the assessment of NOx-sensitivity or VOC-sensitivity for midday ozone production. Evidence from this study indicates that this important discrepancy is not due to the HO_2 measurement or to the sampling of transported plumes but instead to either emissions of unknown organic species that accompany the NO emissions or unknown photochemistry involving nitrogen oxides and hydrogen oxides, possibly the hypothesized reaction OH + NO + O_2 → HO_2 + NO_2.

Item Type:Article
Related URLs:
URLURL TypeDescription
Brune, W. H.0000-0002-1609-4051
Cohen, R. C.0000-0001-6617-7691
Goldstein, A. H.0000-0003-4014-4896
Thornton, J. A.0000-0002-5098-4867
Wennberg, P. O.0000-0002-6126-3854
Additional Information:© 2016 The Royal Society of Chemistry. Received 01 Dec 2015, Accepted 23 Dec 2015. First published online 23 Dec 2015. This article is part of themed collection: Chemistry in the Urban Atmosphere. We thank John Karlik, Rick Ramirez and the other scientists and staff at the University of California Kern County Extension Center for their hospitality and use of their facilities. Participation by WHB, BCB, JT was supported by grants from California Air Resources Board through the University of California, Berkeley (UCB subcontract 00007016) and from NSF (ATM-0706821).
Group:UNSPECIFIED, Division of Geological and Planetary Sciences
Funding AgencyGrant Number
California Air Resources Board00007016
Record Number:CaltechAUTHORS:20160502-143820468
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Official Citation:Ozone production chemistry in the presence of urban plumes W. H. Brune, B. C. Baier, J. Thomas, X. Ren, R. C. Cohen, S. E. Pusede, E. C. Browne, A. H. Goldstein, D. R. Gentner, F. N. Keutsch, J. A. Thornton, S. Harrold, F. D. Lopez-Hilfiker and P. O. Wennberg Faraday Discuss., 2016, 189, 169-189 DOI: 10.1039/C5FD00204D
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:66598
Deposited By: Ruth Sustaita
Deposited On:03 May 2016 18:27
Last Modified:11 Nov 2021 00:00

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