The importance of NOx control for peak ozone mitigation based on a sensitivity study using CMAQ‐HDDM‐3D model during a typical episode over the Yangtze River delta region, China.

Wang, Yangjun; Yaluk, Elly Arukulem; Chen, Hui; Jiang, Sen; Huang, Ling; Zhu, Ansheng; Xiao, Shilin; Xue, Jin; Lu, Guibin; Bian, Jinting; Kasemsan, Manomaiphiboon; Zhang, Kun; Liu, Hanqing; Tong, Huanhuan; Ooi, Maggie Chel Gee; Chan, Andy; Li, Li

Abstract

In recent years, ground-level ozone (O3) has been one of the main pollutants hindering air quality compliance in China's large city-clusters including the Yangtze River Delta (YRD) region. In this work, we utilized the process analysis (PA) and the higher-order decoupled direct method (HDDM-3D) tools embedded in the Community Multiscale Air Quality model (CMAQ) to characterize O3 formation and sensitivities to precursors during a typical O3 pollution episode over the YRD region in July 2018. Results indicate that gas-phase chemistry contributed dominantly to the ground-level O3 although a significant proportion was chemically produced at the middle and upper boundary layer before reaching the surface via diffusion process. Further analysis of the chemical pathways of O3 and Ox formation provided deep insights into the sensitivities of O3 to its precursors that were consistent with the HDDM results. The first-order sensitivities of O3 to anthropogenic volatile organic compounds (AVOC) were mainly positive but small, and temporal variations were negligible compared with those to NOx. During the peak O3 time in the afternoon, the first- and second-order sensitivities of O3 to NOx were significantly positive and negative, respectively, suggesting a convex response of O3 to NOx over most areas including Shanghai, Hangzhou, Nanjing and Hefei. These findings further highlighted an accelerated decrease in ground-level O3 in the afternoon corresponding to continuous decrease of NOx emissions in the afternoon. Therefore, over the YRD region including its metropolises, NOx emission reductions will be more important in reducing the afternoon peak O3 concentration compared with the effect of VOC emission control alone.

Citation

WANG, Y., YALUK, E.A., CHEN, H., JIANG, S., HUANG, L., ZHU, A., XIAO, S., XUE, J., LU, G., BIAN, J., KASEMSAN, M., ZHANG, K., LIU, H., TONG, H., OOI, M.C.G., CHAN, A. and LI, L. 2022. The importance of NOx control for peak ozone mitigation based on a sensitivity study using CMAQ-HDDM-3D model during a typical episode over the Yangtze River delta region, China. Journal of geophysical research: atmospheres [online], 127(9), article e2022JD036555. Available from: https://doi.org/10.1029/2022jd036555

• Journal Article Type: Article
• Acceptance Date: Sep 11, 2022
• Online Publication Date: Sep 30, 2022
• Publication Date: Oct 16, 2022
• Deposit Date: Apr 4, 2023
• Publicly Available Date: Apr 4, 2023
• Journal: Journal of Geophysical Research: Atmospheres
• Print ISSN: 2169-897X
• Electronic ISSN: 2169-8996
• Publisher: American Geophysical Union
• Peer Reviewed: Peer Reviewed
• Volume: 127
• Issue: 19
• Article Number: e2022JD036555
• DOI: https://doi.org/10.1029/2022jd036555
• Keywords: Ground-level ozone (O3); Yangtze River Delta (YRD); Photochemical reactions; Volatile organic compounds (VOCs); Nitrogen oxides (NOx)
• Public URL: https://rgu-repository.worktribe.com/output/1888356
• Related Public URLs: https://rgu-repository.worktribe.com/output/1930696 (Dataset)