Assessment of meteorology vs. control measures in the China fine particular matter trend from 2013 to 2019 by an environmental meteorology index

Gong, Sunling; Liu, Hongli; Zhang, Bihui; He, Jianjun; Zhang, Hengde; Wang, Yaqiang; Wang, Shuxiao; Zhang, Lei; Wang, Jie

doi:https://doi.org/10.5194/acp-21-2999-2021

Articles | Volume 21, issue 4

https://doi.org/10.5194/acp-21-2999-2021

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

https://doi.org/10.5194/acp-21-2999-2021

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

Articles | Volume 21, issue 4

Research article

|

01 Mar 2021

Research article |

| 01 Mar 2021

Assessment of meteorology vs. control measures in the China fine particular matter trend from 2013 to 2019 by an environmental meteorology index

Sunling Gong, Hongli Liu, Bihui Zhang, Jianjun He, Hengde Zhang, Yaqiang Wang, Shuxiao Wang, Lei Zhang, and Jie Wang

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Final revised paper (published on 01 Mar 2021)
Preprint (discussion started on 15 Jul 2020)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Comments to acp-2020-348', Kun Luo, 02 Aug 2020
- AC1: 'Reply to Referee #1', Sunling Gong, 17 Sep 2020
RC2: 'Referee report for acp-2020-348', Anonymous Referee #2, 04 Aug 2020
- AC2: 'Reply to Referee #2', Sunling Gong, 17 Sep 2020

Peer-review completion

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

AR by Sunling Gong on behalf of the Authors (17 Sep 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (01 Oct 2020) by Joshua Fu

RR by Anonymous Referee #2 (01 Oct 2020)

ED: Reconsider after major revisions (16 Oct 2020) by Joshua Fu

AR by Sunling Gong on behalf of the Authors (23 Nov 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (27 Nov 2020) by Joshua Fu

RR by Anonymous Referee #3 (01 Jan 2021)

Suggestions for revision or reasons for rejection

The manuscript developed an environmental meteorology index (EMI) and use this index to further quantify the contributions of meteorology and emission control to the air quality improvement in China from 2013 to 2019. A major concern raised by a previous reviewer is about the inclusion of emission in the definition of EMI. After reviewing the manuscript, review comments and the authors’ response, I sided with the previous reviewer, and think it is a valid concern regarding the emission term in the calculation of EMI. This issue needs to be thoroughly addressed.
1. Including Emis (emission) in their eq. (3) is important for diagnosing accumulation potentials or dispersing potentials, as illustrated in Fig. 3 and discussed in the last paragraph of page 14 and the first paragraph of page 15. Without emis, it would be hard to see how pollutant accumulates or disperse, as the accumulation or dispersion depends not only on meteorology but also on emissions. So for the purpose of calculating accumulation or dispersing potentials, it is fine to include Emis in Eq. (3). In this regard, I agreed with the authors that the exact definition of EMI will depend on scientific objectives the index is used to address.
2. But for the current manuscript, the most important goal is to diagnose contributions of meteorology and emission control to the air quality improvement in China. In the manuscript, Eq. (6) is used to calculate the sole contribution from emission control. One critical term in Eq. (6) is PM (m0, e1), the PM concentration under conditions of unchanged meteorology at p0 but with new emission e1. To get this, the authors then used the ratio of EMI(p0)_bar to EMI(p1)_bar (Eq. (7)). And the authors claim that this ratio can be used to “reflect the impact ratio of sole meteorology variations on the concentrations between p0 and p1 with the same emission at p1” (page 16, lines 10-12). But this argument is flawed, as the formula of EMIS includes emission contribution (Emis in Eq. (1)), as pointed out by the previous reviewer. As emission differences also contribute to the difference in EMI between p0 and p1, the authors can not attribute the ratio EMI(p0)_bar/EMI(p1)_bar to the pure impact of meteorology. So the primary objective of this manuscript, I agreed the previous reviewer and do not think it is appropriate to include the emission term in EMI.
3. It is also important for the authors to quantitatively evaluate the effectiveness of the proposed EMI index for the attribution. For example, it would significantly strengthen this manuscript if the authors can use their CTM to calculate the contribution of emission control to the air quality improvement by perturbing emissions, and then use the CTM results to evaluate the results diagnosed from EMI.

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ED: Publish subject to minor revisions (review by editor) (25 Jan 2021) by Joshua Fu

AR by Sunling Gong on behalf of the Authors (26 Jan 2021) Author's response Author's tracked changes Manuscript

ED: Publish as is (27 Jan 2021) by Joshua Fu

Short summary

Surface concentrations of PM_2.5 in China have had a declining trend since 2013 across the country. This research found that the control measures of emission reduction are the dominant factors in the PM_2.5 declining trends in various regions. The contribution by the meteorology to the surface PM_2.5 concentrations from 2013 to 2019 was not found to show a consistent trend, fluctuating positively or negatively by about 5% on the annual average and 10–20% for the fall–winter heavy-pollution seasons.