Jump to main content
Jump to site search

Volume 189, 2016
Previous Article Next Article

Ozone production chemistry in the presence of urban plumes

Author affiliations

Abstract

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 (HO2), 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 HO2 in NOx-rich plumes. OH production and loss do not balance as they should in the morning, and the ozone production calculated with measured HO2 is a decade greater than that calculated with modeled HO2 when NO levels are high. Calculated ozone production using measured HO2 is twice that using modeled HO2, 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 HO2 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 + O2 → HO2 + NO2.

Back to tab navigation

Supplementary files

Publication details

The article was received on 01 Dec 2015, accepted on 23 Dec 2015 and first published on 23 Dec 2015


Article type: Paper
DOI: 10.1039/C5FD00204D
Author version available: Download Author version (PDF)
Citation: Faraday Discuss., 2016,189, 169-189
  •   Request permissions

    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
    DOI: 10.1039/C5FD00204D

Search articles by author

Spotlight

Advertisements