3D transport characteristics of ozone pollution affected by tropical cyclones over the Greater Bay Area, China: insights from a radar wind profiler network, surface observations, and model simulations

Yang, Yuanjian; Qian, Chenjie; Zhang, Minxuan; Zhan, Chenchao; Liu, Zhenxin; Chan, Pak Wai; Bi, Xueyan; Gao, Meng; Lolli, Simone

doi:10.5194/amt-19-1345-2026

Articles | Volume 19, issue 4

https://doi.org/10.5194/amt-19-1345-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/amt-19-1345-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 19, issue 4

Research article

|

20 Feb 2026

Research article |

| 20 Feb 2026

3D transport characteristics of ozone pollution affected by tropical cyclones over the Greater Bay Area, China: insights from a radar wind profiler network, surface observations, and model simulations

Yuanjian Yang, Chenjie Qian, Minxuan Zhang, Chenchao Zhan, Zhenxin Liu, Pak Wai Chan, Xueyan Bi, Meng Gao, and Simone Lolli

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Final revised paper (published on 20 Feb 2026)
Preprint (discussion started on 03 Nov 2025)

Interactive discussion

Status: closed

RC1:
'Comment on egusphere-2025-4668', Anonymous Referee #2, 18 Nov 2025

This manuscript presents a significant and timely contribution to our understanding of ozone

pollution dynamics in the GBA under tropical cyclone influence. The study provides a

comprehensive three-dimensional characterization of O3 transport mechanisms during TC

events, thereby moving beyond previous work that has primarily focused on general TC-O3

relationships. The combination of high-temporal-resolution wind profile measurements with

hourly meteorological and air quality observations, supplemented by model simulations,

represents a methodologically robust approach that enables detailed process-level

understanding. The manuscript offers valuable quantitative insights into distance-dependent

transport mechanisms. Notably, the finding that TC activity accounts for 39.9% of O3

pollution episodes underscores the practical importance of this work for pollution forecasting

and mitigation strategies in the GBA and other TC-affected bay regions globally.

Despite these considerable strengths, several aspects of the manuscript would benefit from

further clarification and refinement to strengthen its scientific contribution and accessibility to

the broader readership. Therefore recommend this manuscript for publication after minor

revisions addressing the following points:

1.Formatting issues with superscript units. Multiple instances of incorrect superscript

formatting for units such as "μg m -3" and "m s -1" are found throughout the manuscript.

Please check and correct all unit expressions consistently throughout the text.

2.Lines 290-295: There appears to be a date inconsistency in this section. Please clarify

whether the events occurred in July or August.

3.Line 295: The model results do not adequately address whether the elevated ozone

concentrations at the HD site on the 23rd-24th were primarily due to local photochemical

production or regional transport. Please provide additional analysis.

4.Line 341: There is an inconsistency in the surface wind direction for the HK on August

24th. Line 281 and Figure 5c both indicate southwesterly winds, while Line 341 describes

northwesterly winds. Please verify the actual wind direction from the observational data and

correct this discrepancy.

5.Line371-374: How does the RI value at the GZ site indicate the occurrence of convergence?

Does " which led to reduced wind speeds within the boundary layer" refer to horizontal or

vertical wind speed? Please specify.And The explanation in lines 371-374 transitions abruptly

from wind speed changes to terrain and urbanization effects. Please provide more detailed

explaining.

6.Line 376: Based on Figure 10, O₃ appears to be more uniformly mixed within the boundary

layer at the GZ site, which seems inconsistent with the text description.

7.Line 385-392: The relationship between O₃ and VWS requires more detailed explanation. Specifically, the authors should clarify: (1) how VWS magnitude corresponds to O₃ levels

(i.e., whether larger/smaller VWS values correspond to higher or lower O₃ concentrations),

and (2) how changes in VWS affect o O₃ concentrations. Currently, this section provides

minimal explanation of these mechanisms . And "But the HK station had a higher boundary

layer height that could accommodate more O₃." this statement appears contradictory: if the

boundary layer can accommodate more O₃, one might reasonably infer that O₃ concentrations

would be lower. However, the HK actually exhibits higher O₃ concentrations. The authors

should provide more comprehensive explanations to reconcile this apparent inconsistency and

ensure logical coherence in their interpretation.

Citation: https://doi.org/10.5194/egusphere-2025-4668-RC1
- AC1: 'Reply on RC1', Yuanjian Yang, 28 Dec 2025
  
  Please the supplement
  
  Citation: https://doi.org/10.5194/egusphere-2025-4668-AC1
- AC2: 'Reply on RC1', Yuanjian Yang, 28 Dec 2025
  
  Please the supplement
  
  Citation: https://doi.org/10.5194/egusphere-2025-4668-AC2
RC2:
'Comment on egusphere-2025-4668', Anonymous Referee #1, 24 Nov 2025

This study examines the three-dimensional transport characteristics of ozone (O3) pollution in the Greater Bay Area (GBA) under the influence of tropical cyclones (TCs). The integration of wind profiler radar observations, surface measurements, and model analysis is a key strength, offering valuable insights into how TC-induced circulation modulates both horizontal and vertical O3 transport. The impacts of TCs on O3 pollution exhibit a systematic variation with distance from the GBA: horizontal advection dominates at distant locations (1800–2000 km), enhanced subsidence and downward transport become significant at intermediate distances (1000–1700 km), and strong vertical wind shear drives boundary-layer mixing and coastal O3 enhancement when TCs move within 800 km of the region. The manuscript is generally well-organized, and the identification of three transport phases provides an important understanding of the dynamic processes influencing O3 variability during TC events. However, I have several suggestions to improve the study:
Major comments:
How did the authors isolate the impact of tropical cyclones on O3 pollution from other synoptic-scale weather systems?
What datasets were used to validate the WRF-Chem model outputs, and how was the evaluation conducted?
Why was the role of VOCs in O3 formation and pollution during TC events not analyzed in the study?
What are the spatial resolutions of all datasets used in the research?
Minor comments:
Page 4, Lines 110–112: The detection heights of the wind profiler radar differ across the three stations. Could this difference affect the vertical profile data?
Page 4, Line 119: The temporal resolution of the best-track TC dataset is 6 hours. Could you clarify how this dataset is matched with the 1-hour resolution data used in the study?
Page 4, Line 120: Please provide references defining “TC days.”
Page 5, Line 131: Please provide a reference for the national standard of "MDA8", e.g., doi: 10.1016/j.rse.2021.112775
Page 5, Line 132: Please provide references that define "O3 pollution" in the GBA.
Table 2: Please include the calculation methods for the statistical metrics, such as MB, FE, and FB.
Page 8, Line 201: Please clarify the standard used to define "O3 pollution day" and cite related references, for example: doi:10.1016/j.rse.2024.114482
Page 9, Lines 220–221: Please provide possible explanations for the observed results.
Figure 3: Some regions in the figure appear to lack data. Please clarify.
Page 13, Line 239: It appears that subfigure (d) is missing from the figure.
Figure 10: The units of O3 in the text are µg/m3, but they are given in ppmv here. Please maintain consistency in the units.
Figure 12: Why do the VWS grids differ in size among the three station regions? Please clarify this discrepancy.

Citation: https://doi.org/10.5194/egusphere-2025-4668-RC2
- AC3: 'Reply on RC2', Yuanjian Yang, 28 Dec 2025
  
  Please the supplement
  
  Citation: https://doi.org/10.5194/egusphere-2025-4668-AC3

Peer review completion

AR – Author's response | RR – Referee report | ED – Editor decision | EF – Editorial file upload

AR by Yuanjian Yang on behalf of the Authors (29 Dec 2025) Author's response Author's tracked changes

EF by Mario OESO (02 Jan 2026) Manuscript

ED: Referee Nomination & Report Request started (04 Jan 2026) by Haichao Wang

RR by Anonymous Referee #1 (04 Jan 2026)

ED: Publish as is (10 Jan 2026) by Haichao Wang

AR by Yuanjian Yang on behalf of the Authors (17 Jan 2026) Manuscript

Post-review adjustments

AA – Author's adjustment | EA – Editor approval

AA by Yuanjian Yang on behalf of the Authors (18 Feb 2026) Author's adjustment Manuscript

EA: Adjustments approved (19 Feb 2026) by Haichao Wang

Short summary

Up to ~ 40 % of ozone pollution in the Greater Bay Area of China is related to tropical cyclones. The O₃ pollution was found to be transported from inland areas to coastal areas. The transport process can be roughly divided into three phases: downdraft control, horizontal transport, and vertical mixing.