The impact of inhomogeneous emissions and topography on ozone photochemistry in the vicinity of Hong Kong Island

Wang, Yuting; Ma, Yong-Feng; Muñoz-Esparza, Domingo; Li, Cathy W. Y.; Barth, Mary; Wang, Tao; Brasseur, Guy P.

doi:https://doi.org/10.5194/acp-21-3531-2021

Articles | Volume 21, issue 5

https://doi.org/10.5194/acp-21-3531-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/acp-21-3531-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 21, issue 5

Research article

|

09 Mar 2021

Research article |

| 09 Mar 2021

The impact of inhomogeneous emissions and topography on ozone photochemistry in the vicinity of Hong Kong Island

Yuting Wang, Yong-Feng Ma, Domingo Muñoz-Esparza, Cathy W. Y. Li, Mary Barth, Tao Wang, and Guy P. Brasseur

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Final revised paper (published on 09 Mar 2021)
Preprint (discussion started on 30 Sep 2020)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'Interactive comment', Anonymous Referee #1, 27 Oct 2020
- AC1: 'Responses to Referee 1', Yuting Wang, 22 Dec 2020
RC2: 'The impact ofinhomogeneous emissions and topography onozone photochemistry in the vicinity of the HongKong island', Anonymous Referee #2, 04 Nov 2020
- AC2: 'Responses to Referee 2', Yuting Wang, 22 Dec 2020
AC3: 'Manuscript-track-changes', Yuting Wang, 22 Dec 2020

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Yuting Wang on behalf of the Authors (22 Dec 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (30 Dec 2020) by Jason West

RR by Anonymous Referee #1 (12 Jan 2021)

Suggestions for revision or reasons for rejection

The authors addressed most of the concerns. There are some remaining issues.

1. In the revised manuscript, it states “With an OH concentration of 5 x 10^6 molecule cm-3, the corresponding chemical lifetimes of RH-A and RH-B are approximately 2 days and 30 minutes, respectively.” However, in the response to reviewers, it states “The daytime chemical lifetimes between the two different species are very different: 5.5 hours for RH-A (propane-like) and 3 minutes for RH-B (isoprene-like), assuming that the OH concentration is 5 x 10^6 cm-3.” Please clarify the differences and how they are calculated.

2. The manuscript now provides a good review of previous studies in the introduction section. It would be helpful to include more of these studies in the comparison in the result section. Studies such as Krol et al. (2000), Li et al. (2016), and Kim et al. (2016) also calculated Damköhler number and/or intensity of segregation. Also, besides simply compare the values, please provide brief explanations about why they are consistent or different.

3. It is necessary to acknowledge the difficulties in representing PBL processes and cloud convection in WRF. Even though the modified 𝜃v gradient method or other methods used in the study were consistent with PBL from WRF, it doesn’t guarantee the results are realistic, especially without comparing with observations. It would be helpful to add the following citations which studied the gaps in different ways.
Barth et al., Atmos. Chem. Phys., 7, 4709–4731, 2007
Li et al., Atmospheric Environment 199, 88–101, 2019
Mapes et al., J. Atmos. Sci., 61(11), 1284–1295, 2014

4. For Table 1, please explain why some reaction rates have been revised. Have the authors redone all the simulations using these updated rates?

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RR by Anonymous Referee #2 (13 Jan 2021)

ED: Publish subject to technical corrections (23 Jan 2021) by Jason West

AR by Yuting Wang on behalf of the Authors (29 Jan 2021) Author's response Manuscript

Short summary

Large-eddy simulations (LESs) were performed in the mountainous region of the island of Hong Kong to investigate the degree to which the rates of chemical reactions between two reactive species are reduced due to the segregation of species within the convective boundary layer. We show that the inhomogeneity in emissions plays an important role in the segregation effect. Topography also has a significant influence on the segregation locally.