Ambient ozone (O3) concentrations in Southeast Michigan (SEMI) can exceed the U.S. National Ambient Air Quality Standard. Despite past efforts to measure O3precursors and elucidate reaction mechanisms, changing emission patterns and atmospheric composition in SEMI warrant new measurements and updated mechanisms to understand the causes of observed O3exceedances. In this study, we examine the chemical drivers of O3exceedances in SEMI, based on the Phase I MOOSE (Michigan‐Ontario Ozone Source Experiment) field study performed during May to June 2021. A zero‐dimensional (0‐D) box model is constrained with measurement data of meteorology and trace gas concentrations. Box model sensitivity simulations suggest that the formaldehyde to nitrogen dioxide ratio (HCHO/NO2) for the transition between the volatile organic compounds (VOCs)‐ and nitrogen oxides (NO
Examining the Summertime Ozone Formation Regime in Southeast Michigan Using MOOSE Ground-Based HCHO/NO2 Measurements and F0AM Box Model
The summertime surface ozone (O3) concentrations over Southeast Michigan (SEMI) often exceed 70 ppbv. However, the associated O3 formation regime is still not well known. In this study, we examined the chemical drivers of O3 exceedances in SEMI, based on the Michigan-Ontario Ozone Source Experiment (MOOSE) field campaign during the period of May 20 – June 30, 2021. We employed a zero-dimensional (0-D) box model, which was constrained by measurements of meteorology and trace gas concentrations during MOOSE. Our model simulations demonstrated that the formaldehyde to nitrogen dioxide ratio (HCHO/NO2) for the transition between the VOC- and NOx-limited O3 production regimes was 3.0 ± 0.3 (mean ± 1σ) in SEMI. The midday (12:00-16:00) averaged HCHO/NO2 ratio during MOOSE was 1.62 ± 1.03, suggesting that O3 production in SEMI was likely limited by VOC emissions. Our study has significant implications for air quality policy and the design of effective O3 pollution control strategies through ground-based HCHO/NO2 measurements and model simulations.
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- Award ID(s):
- 2126097
- NSF-PAR ID:
- 10508789
- Publisher / Repository:
- American Geophysical Union
- Date Published:
- Format(s):
- Medium: X
- Location:
- San Francisco, CA
- Sponsoring Org:
- National Science Foundation
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Abstract x )‐limited O3production regimes is 3.0 ± 0.3 in SEMI. The midday (12:00–16:00) averaged HCHO/NO2ratio during the MOOSE Phase I study is 1.62 ± 1.03, suggesting that O3production in SEMI is limited by VOC emissions. This finding implies that imposing stricter regulations on VOC emissions should be prioritized for the SEMI O3nonattainment area. This study, through its use of ground‐based HCHO/NO2ratios and box modeling to assess O3‐VOC‐NOx sensitivities, has significant implications for air quality policy and the design of effective O3pollution control strategies, especially in O3nonattainment areas. -
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