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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


Yangjun Wang

Elly Arukulem Yaluk

Hui Chen

Sen Jiang

Ling Huang

Ansheng Zhu

Shilin Xiao

Jin Xue

Guibin Lu

Jinting Bian

Manomaiphiboon Kasemsan

Kun Zhang

Hanqing Liu

Huanhuan Tong

Maggie Chel Gee Ooi

Li Li


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.


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:

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
Keywords Ground-level ozone (O3); Yangtze River Delta (YRD); Photochemical reactions; Volatile organic compounds (VOCs); Nitrogen oxides (NOx)
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WANG 2022 The importance of NOx (VOR) (6.2 Mb)

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Copyright Statement
© 2022. The Authors. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

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