Preprints
https://doi.org/10.5194/egusphere-2024-3070
https://doi.org/10.5194/egusphere-2024-3070
25 Oct 2024
 | 25 Oct 2024

A Better Understanding of an Extremely High Ozone Episode with Ensemble Simulation

Jinhui Gao and Hui Xiao

Abstract. Severe ozone pollutions may occur in the Great Bay Area (GBA) when typhoons approach South China. However, numerical models often fail to capture the high ozone concentrations during the episodes, leading to uncertainties in understanding their formation mechanisms. This study conducted an ensemble simulation with 30 members (EMs) using the WRF-Chem model, coupled with a self-developed ozone source apportionment method, to analyze an extremely high ozone episode associated with Typhoon NIDA in the summer of 2016. The newly proposed index effectively distinguished between well-performing (good) and poorly performing (bad) EMs. Compared to the bad EMs, the good EMs accurately reproduced surface ozone variations, particularly capturing the extremely high concentrations observed in the afternoon of July 31. The formation of such high ozone levels was attributed to the retention of ozone in the residual layer at night and the enhanced photochemistry during daytime. As Typhoon NIDA approached, weak winds confined large amounts of ozone in the residual layer at night. The development of planetary boundary layer (PBL) facilitated the downward transport of ozone aloft, contributing to the rapid increase in surface ozone in the following morning. The enhanced photochemistry was primarily driven by increased ozone precursors resulting from favorable accumulation conditions and enhanced biogenic emissions. During the period of high ozone concentrations, contributions from local and surrounding regions increased. Additionally, ozone from southeastern Asia could transport to the GBA at high altitudes and then contribute to surface ozone when the PBL developed.

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Journal article(s) based on this preprint

14 Jul 2025
The skill at modeling an extremely high ozone episode varies substantially amongst ensemble simulation
Jinhui Gao and Hui Xiao
Atmos. Chem. Phys., 25, 7387–7401, https://doi.org/10.5194/acp-25-7387-2025,https://doi.org/10.5194/acp-25-7387-2025, 2025
Short summary
Jinhui Gao and Hui Xiao

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-3070', Anonymous Referee #1, 22 Nov 2024
    • AC1: 'Reply on RC1', Jinhui Gao, 25 Apr 2025
  • CC1: 'Comment on egusphere-2024-3070', H. Kang, 16 Dec 2024
    • AC3: 'Reply on CC1', Jinhui Gao, 25 Apr 2025
  • RC2: 'Comment on egusphere-2024-3070', Anonymous Referee #2, 05 Mar 2025
    • AC2: 'Reply on RC2', Jinhui Gao, 25 Apr 2025

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-3070', Anonymous Referee #1, 22 Nov 2024
    • AC1: 'Reply on RC1', Jinhui Gao, 25 Apr 2025
  • CC1: 'Comment on egusphere-2024-3070', H. Kang, 16 Dec 2024
    • AC3: 'Reply on CC1', Jinhui Gao, 25 Apr 2025
  • RC2: 'Comment on egusphere-2024-3070', Anonymous Referee #2, 05 Mar 2025
    • AC2: 'Reply on RC2', Jinhui Gao, 25 Apr 2025

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Jinhui Gao on behalf of the Authors (25 Apr 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Publish subject to minor revisions (review by editor) (25 Apr 2025) by Rob MacKenzie
AR by Jinhui Gao on behalf of the Authors (28 Apr 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Publish as is (29 Apr 2025) by Rob MacKenzie
AR by Jinhui Gao on behalf of the Authors (29 Apr 2025)

Journal article(s) based on this preprint

14 Jul 2025
The skill at modeling an extremely high ozone episode varies substantially amongst ensemble simulation
Jinhui Gao and Hui Xiao
Atmos. Chem. Phys., 25, 7387–7401, https://doi.org/10.5194/acp-25-7387-2025,https://doi.org/10.5194/acp-25-7387-2025, 2025
Short summary
Jinhui Gao and Hui Xiao
Jinhui Gao and Hui Xiao

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Short summary
The ensemble simulation provides a solution to better reproduce and understand the extremely high ozone episode occurred in the GBA when Typhoon NIDA approached South China in summer 2016. Elevated temperatures and weak winds contributed to the increase in ozone precursors, resulting in enhanced ozone production. Large amounts of ozone aloft also contributed to the increase in surface ozone via vertical transport. Notably, ozone from Southeast Asia contributed through this mechanism.
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