Preprints
https://doi.org/10.5194/acp-2020-1286
https://doi.org/10.5194/acp-2020-1286

  08 Mar 2021

08 Mar 2021

Review status: a revised version of this preprint was accepted for the journal ACP and is expected to appear here in due course.

A Comparative Study to Reveal the Influence of Typhoons on the Transport, Production and Accumulation of O3 in the Pearl River Delta, China

Kun Qu1,2, Xuesong Wang1,2, Yu Yan1,2, Jin Shen3, Teng Xiao1,2, Huabin Dong1,2, Limin Zeng1,2, and Yuanhang Zhang1,2,4,5 Kun Qu et al.
  • 1State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
  • 2International Joint Laboratory for Regional Pollution Control, Ministry of Education, Beijing, 100816, China
  • 3State Key Laboratory of Regional Air Quality Monitoring, Guangdong Key Laboratory of Secondary Air Pollution Research, Guangdong Environmental Monitoring Center, Guangzhou 510308, China
  • 4Beijing Innovation Center for Engineering Science and Advanced Technology, Peking University, Beijing 100871, China
  • 5CAS Center for Excellence in Regional Atmospheric Environment, Chinese Academy of Sciences, Xiamen 361021, China

Abstract. The Pearl River Delta (PRD) region in South China is faced with severe ambient O3 pollution in autumn and summer, which mostly coincides with the occurrence of typhoons above the Northwest Pacific. With increasingly severe O3 pollution in the PRD under the influence of typhoons, it is necessary to gain a comprehensive understanding of the impact of typhoons on O3 transport, production and accumulation for efficient O3 reduction. In this study, we analysed the general influence of typhoons on O3 pollution in the PRD via systematic comparisons of meteorological conditions, O3 processes and sources on O3 pollution days with and without typhoon occurrence (denoted as the typhoon-induced and no-typhoon scenarios, respectively), and also examined the differences in these influences in autumn and summer. The results show that the approach of typhoons was accompanied by higher wind speeds and strengthened downdrafts in autumn as well as the inflows of more polluted air masses in summer, suggesting favourable O3 transport conditions in the typhoon-induced scenario in both seasons. However, the effect of typhoons on the production and accumulation of O3 were distinct. Typhoons led to reduced cloud cover, and thus stronger solar radiation in autumn, which accelerated O3 production, but the shorter residence time of local air masses was unfavourable for the accumulation of O3 within the PRD. In contrast, in summer, typhoons increased cloud cover, and weakened solar radiation, thus restraining O3 formation, but the growing residence time of local air masses favoured O3 accumulation. The modelling results using the Community Multiscale Air Quality (CMAQ) model for the typical O3 pollution days suggest increasing contributions from the transport processes as well as sources outside the PRD for O3 pollution, confirming enhanced O3 transport under typhoon influence in both seasons. The results of the process analysis in CMAQ suggest that the chemical process contributed more in autumn but less in summer in the PRD. Since O3 production and accumulation cannot be enhanced at the same time, the proportion of O3 contributed by emissions within the PRD was likely to decrease in both seasons. The difference in the typhoon influence on O3 processes in autumn and summer can be attributed to the seasonal variation of the East Asian monsoon. From the meteorology-process-source perspective, this study revealed the complex influence of typhoons on O3 pollution in the PRD and their seasonal differences. To alleviate O3 pollution under typhoon influence, emission control is needed on a larger scale, rather than only within the PRD.

Kun Qu et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2020-1286', Anonymous Referee #2, 05 Apr 2021
    • RC2: 'Reply on RC1', Anonymous Referee #1, 05 Apr 2021
      • AC2: 'Reply on RC2', Xuesong Wang, 03 May 2021
    • AC1: 'Reply on RC1', Xuesong Wang, 03 May 2021

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2020-1286', Anonymous Referee #2, 05 Apr 2021
    • RC2: 'Reply on RC1', Anonymous Referee #1, 05 Apr 2021
      • AC2: 'Reply on RC2', Xuesong Wang, 03 May 2021
    • AC1: 'Reply on RC1', Xuesong Wang, 03 May 2021

Kun Qu et al.

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Short summary
Typhoons above the Northwest Pacific frequently lead to severe ambient ozone pollution in the Pearl River Delta, China in autumn and summer. However, typhoons do not enhance ozone transport, production and accumulation at the same time, and differences also exist between these influences in two seasons. Through systematic comparisons, we revealed the complex interactions between local meteorology and ozone processes, which is essential to understand the causes of regional ozone pollution.
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