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Ozone Formation under high NOx conditions: Insights from the AEROMMA NYC-METS field campaign
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Ozone Formation under high NOx conditions: Insights from the AEROMMA NYC-METS field campaign

Ezra Wood, Khaled Shaifullah Joy, Andrew John Lindsay and Lee Vincent Feinman
EGU General Assembly 2025
15 Mar 2025
url
https://doi.org/10.5194/egusphere-egu25-12780View
Published, Version of Record (VoR) Open

Abstract

Despite well over a half century of research, gaps remain in our understanding of ozone formation chemistry. Net ozone formation results from the oxidation of NO to NO2 by peroxy radicals (HO2 and RO2) followed by photolysis of NO2. Measurements of peroxy radicals made by several analytical methods over the past decade in numerous locations across the world have revealed discrepancies under high NOx conditions ([NO] > 1 ppb), with zero-dimensional models apparently underestimating peroxy radical concentrations and ozone production rates (P(O3)) by up to a factor of eight. These findings suggest that models may misidentify when ozone formation is NOx-limited vs. NOx-saturated (VOC-limited) and that our knowledge of the relevant reactions is incomplete. To investigate these anomalously high P(O3) values at high NOx, we used the Drexel University Ethane Chemical AMPlifier (ECHAMP) instrument to measure total peroxy radicals at a roof-top site in Manhattan (NYC) as part of the NOAA AEROMMA/NYC-METS project. A wide assortment of other measurements were made by spectroscopic and mass spectrometric methods. We will present results from this field project with special emphasis on our measurements during a few “high-NOx” periods (roughly defined as daytime periods with NO mixing ratios greater than 1 ppb).

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