Ground-Based MAX-DOAS Observations of Tropospheric Ozone and Its Precursors for Diagnosing Ozone Formation Sensitivity
Diagnosing ozone (O<sub>3</sub>) formation sensitivity using tropospheric observations of O<sub>3</sub> and its precursors is important for formulating O<sub>3</sub> pollution control strategies. Photochemical reactions producing O<sub>3</sub> occur at...
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| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-02-01
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| Series: | Remote Sensing |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2072-4292/17/4/658 |
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| Summary: | Diagnosing ozone (O<sub>3</sub>) formation sensitivity using tropospheric observations of O<sub>3</sub> and its precursors is important for formulating O<sub>3</sub> pollution control strategies. Photochemical reactions producing O<sub>3</sub> occur at the earth’s surface and in the elevated layers, indicating the importance of diagnosing O<sub>3</sub> formation sensitivity at different layers. Synchronous measurements of tropospheric O<sub>3</sub> and its precursors nitrogen dioxide (NO<sub>2</sub>) and formaldehyde (HCHO) were performed in urban Hefei to diagnose O<sub>3</sub> formation sensitivity at different atmospheric layers using multi-axis differential optical absorption spectroscopy observations. The retrieved surface NO<sub>2</sub> and O<sub>3</sub> were validated with in situ measurements (correlation coefficients (R) = 0.81 and 0.80), and the retrieved NO<sub>2</sub> and HCHO vertical column densities (VCDs) were consistent with TROPOMI results (R = 0.81 and 0.77). The regime transitions of O<sub>3</sub> formation sensitivity at different layers were derived using HCHO/NO<sub>2</sub> ratios and O<sub>3</sub> profiles, with contributions of VOC-limited, VOC-NO<sub>x</sub>-limited, and NO<sub>x</sub>-limited regimes of 74.19%, 7.33%, and 18.48%, respectively. In addition, the surface O<sub>3</sub> formation sensitivity between HCHO/NO<sub>2</sub> ratios and O<sub>3</sub> (or increased O<sub>3</sub>, ΔO<sub>3</sub>) had similar regime transitions of 2.21–2.46 and 2.39–2.71, respectively. Moreover, the O<sub>3</sub> formation sensitivity of the lower planetary boundary layer on polluted and non-polluted days was analyzed. On non-polluted days, the contributions of the VOC-limited regime were predominant in the lower planetary boundary layer, whereas those of the NO<sub>x</sub>-limited regime were predominant in the elevated layers during polluted days. These results will help us understand the evolution of O<sub>3</sub> formation sensitivity and formulate O<sub>3</sub> mitigation strategies in the Yangtze River Delta region. |
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| ISSN: | 2072-4292 |