Articles | Volume 21, issue 15
© Author(s) 2021. This work is distributed underthe Creative Commons Attribution 4.0 License.
A comparative study to reveal the influence of typhoons on the transport, production and accumulation of O3 in the Pearl River Delta, China
- Final revised paper (published on 04 Aug 2021)
- Supplement to the final revised paper
- Preprint (discussion started on 08 Mar 2021)
- Supplement to the preprint
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
- RC2: 'Reply on RC1', Anonymous Referee #1, 05 Apr 2021
Peer review completion
AR: Author's response | RR: Referee report | ED: Editor decision
AR by Xuesong Wang on behalf of the Authors (07 May 2021)  Author's response Author's tracked changes Manuscript
ED: Referee Nomination & Report Request started (15 May 2021) by Xavier Querol
RR by Anonymous Referee #2 (04 Jun 2021)
RR by Anonymous Referee #3 (14 Jun 2021)
RR by Anonymous Referee #4 (15 Jun 2021)
ED: Publish subject to minor revisions (review by editor) (22 Jun 2021) by Xavier Querol
AR by Xuesong Wang on behalf of the Authors (08 Jul 2021)  Author's response Author's tracked changes Manuscript
ED: Publish as is (08 Jul 2021) by Xavier Querol
The manuscript provides thorough analysis of the influence of typhoons on the occurrence of ozone episodes in the Pearl River Delta, China.
Despite many papers (correctly referenced by the Authors) have been published concerning ozone pollution in the area, the manuscript resumes the different aspect of ozone episodes development and can be a guide through previous literature. The modelling section is, from my point of view, the most important to provide a clear support to the hypothesis and correlations provided by the previous analysis. A possible missing point is the evaluation of the overall import/export of ozone, to estimate if the PRD region is responsible of a net export of ozone increasing the amount of pollutant over the region.
The overall result that typhoon influenced O3 episodes have a major contribution from long range transport (from outside the model domain) and advection from nearby China regions has relevant policy implications that are only quickly commented in the conclusions and would merit a wider discussion. Local O3 precursor emission control can be expected to have a limited effectiveness and regional policies seem definitely needed, at China national level but even at South and East Asia regional level, to be able to reduce population exposure and overall ozone production.
The manuscript is well written and needs few clarifications/integrations to reach publication quality.
This is due to the O3 persistence in the atmosphere due to its relatively long lifetime in the atmosphere. The Authors should consider mentioning it.
“of” just before the symbol “>” should be removed.
Why precipitation is not considered?
Does the mentioned “30%” refers to the total number of days or to the number of polluted days?
This consideration seems convincing for July only. For October the difference of values with/without typhoons seems rather small.
This is not clear, what is the reason to discard 5 episodes?
Why the endpoint of the back trajectories has been set to 500m and not nearer the surface?
What is the horizontal space resolution of the mentioned matrix?
Setting the trajectory starting points to 100m seems reasonable for industrial emissions, but it seems high for road transport related emissions or other surface sources.
Were time durations attributed to points and then gridded? on which target grid?
The sentence “model, the CMAQ model (version 5.0.2)” should be simplified to avoid useless word repetition.
The meaning of the sentence “all O3 pollution days in these two months served as representative O3 pollution days under multiple scenarios.” is not clear.
The meaning of this sentence is not clear.
“CMAQ model”, or “model application” would read better that “CMAQ modelling”.
Alternatively to zero emission a fractional reduction could be applied to reduce non linearity. See e.g. https://fairmode.jrc.ec.europa.eu/activity/ct1
The Authors should comment this alternative approach and the reasons supporting their choice.
3 Comparison of meteorological conditions
It is not clear how ERA-Interim fields have been processed. Has a gridded area been processed or timeseries have been extracted in few points? What choice has been done and why?
The reference to first and second categories in Sect 2.1 is not clear.
This sentence is not clear. Does it mean that during the summer the air masses advected by slow wind are expected to bring higher O3 concentration? Or with low wind speed local phenomena would prevail on advection?
The reference to Sect 2.1 is not clear.
Are values in Figure 4 mean values over the considered time period?
Downdrafts seem to be at higher levels from the Figure. Please refer to the Figure vertical scale in hPa to be better understood by the reader.
How values in Figure 6 have been computed from ERA-Interim fields? Are they mean values?
The meaning of the sentence is obscure, what does “and offset the influence of weakened O3 formation to some extent.” mean?
Please relate to the unfavourable/favourable conditions for ozone formation shown in the previous sections.
4 Comparisons of O3 processes and sources
I can't find this number in Figure 10.
This discussion about anthropogenic emissions control is relevant and should be expanded to provide useful input to air quality management and suggestions to conceive measures capable to reduce the population exposure and the production of ozone at global scale.