Analysis of influential factors for the relationship between PM<sub>2.5</sub> and AOD in Beijing

Zheng, Caiwang; Zhao, Chuanfeng; Zhu, Yannian; Wang, Yang; Shi, Xiaoqin; Wu, Xiaolin; Chen, Tianmeng; Wu, Fang; Qiu, Yanmei

doi:https://doi.org/10.5194/acp-17-13473-2017

Articles | Volume 17, issue 21

https://doi.org/10.5194/acp-17-13473-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/acp-17-13473-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 17, issue 21

Research article

|

13 Nov 2017

Research article |

| 13 Nov 2017

Analysis of influential factors for the relationship between PM_2.5 and AOD in Beijing

Caiwang Zheng, Chuanfeng Zhao, Yannian Zhu, Yang Wang, Xiaoqin Shi, Xiaolin Wu, Tianmeng Chen, Fang Wu, and Yanmei Qiu

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Final revised paper (published on 13 Nov 2017)
Preprint (discussion started on 17 Feb 2017)

Interactive discussion

Status: closed

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

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RC1: 'Review comments on "Analysis of Influential Factors for the Relationship between PM2.5 and AOD in Beijing"', Anonymous Referee #1, 07 Mar 2017
RC2: 'review in attached pdf', Anonymous Referee #3, 04 Jun 2017
AC1: 'Responses to Reviewers for "Analysis of Influential Factors for the Relationship between PM2.5 and AOD in Beijing"', Chuanfeng Zhao, 14 Jul 2017

Peer-review completion

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

AR by Chuanfeng Zhao on behalf of the Authors (14 Jul 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (06 Aug 2017) by Xiaohong Liu

RR by Anonymous Referee #4 (21 Aug 2017)

Suggestions for revision or reasons for rejection

Review of Zheng et al., “Analysis of influential factors for the relationship between PM2.5 and AOD in Beijing” submitted for publication in ACP.

General comments
The authors investigate the relationship between AOD and PM2.5 using 5 years of data in Beijing, figuring out the impacts of different influential factors to this relationship including PBLH, RH, wind speed and direction and aerosol type. This is a complex study, which found valuable and interesting quantitative results regarding the impacts of most influential factors to AOD-PM2.5 relationship.

Relationship between PM2.5 and aerosol optical depth (AOD) is often investigated in order to obtain surface PM2.5 from satellite observation of AOD with a broad area coverage. Various factors could affect the AOD-PM2.5 regressions, but they have not yet been systematically evaluated. This study evaluates the influence of most various factors to the AOD-PM2.5 relationship quantitatively, and thus could have a broad influence. This will help future derivation of accurate PM2.5 from satellite AOD observations. The authors have done a very good reply to the previous reviewers’ comments. The paper is also written well, but some language corrections/improvements are needed as detailed below. I would recommend its publication after a minor revision.

Detailed Comments
1. Many “aerosols” in the manuscript could be changed as “aerosol”.
2. Page 4, line 8, “are associated with” should be “is associated with”
3. Page 5, line 5, ‘observations’ -> ‘observation’
4. Page 5, line 11, ‘has not’ should be changed as “has no” or “has not a”
5. Page 6, lines 9 and 18, “includes” should be changed to “include”
6. Page 7, line 11, ‘ensure’ should be ‘ensures’
7. Page 8, “RH” and “PBLH” have been denoted earlier.
8. Page 8, please make sure whether you are using “PBLH” or “BLH” for planetary boundary layer height and keep them consistent.
9. Page 9, line 5, change ‘are’ to ‘is’
10. Page 10, line 2, change ‘is’ to ‘are’
11. Page 10, line 15, change ‘is’ to ‘are’
12. Page 11, line 4, delete ‘has’
13. Page 11, line 6, ‘PM2.5’ to ‘PM2.5’
14. Page 13, line 4, ‘including those from both MODIS and CALIPSO’
15. Page 13, line 6, ‘AODs at time within 30-min frame’
16. Page 14, line 2, ‘AOD’ -> ‘AODs’
17. Page 14, line 6, ‘substantial’ -> ‘large’
18. Page 16, line 1, ‘observational studies’
19. Page 16, line 11, please use ‘PBLH’ for consistency.
20. Page 17, line 6-9, you could modify the sentence as “Clearly, there is generally an anti-correlated temporal trend between PBLH and RH. The averaged PBLHs for 2011 to 2015 are 2.56 km, 1.97 km, 1.55 km and 1.32 km with corresponding averaged RHs of 27.58%, 48.73%, 42.78% and 33.05%in MAM, JJA, SON and DJF, respectively”
21. Page 17, line 12, ‘imply’ -> ‘implies’
22. Page 17, line 19, ‘trend’ -> ‘trends’
23. Page 18, line 18, delete ‘promising’
24. Page 19, lines 6-10, the descriptions could be further improved.
25. Page 19, line 21, ‘R2 values”
26. Page 21, line 8, change ‘decrease’ to ‘decreases’
27. Page 22, line 9, using ‘and thus not shown here”.
28. Page 23, line 11, ‘implies’->’imply’
29. Page 24, line 8, please delete “Different from the wind speed which will be analyzed in Figs. 12 and 13”
30. Page 26, line 16, ‘distribution also’
31. Page 26, line 17, ‘ADO integrated from surface to’
32. Page 28, line 3, ‘AOD’ changes to ‘AODs’
33. Page 28, lines 5 and 7, ‘a RMS’ -> ‘an RMS’
34. Page 28, line 12, I would suggest “With the correction of RH and PBLH to AOD, R2 of monthly averaged PM2.5 and AOD increases from 0.63 to 0.76 at 14:00 LT, …”
35. Page 29, lines 2-4, “The occurrence rate of good air quality (PM2.5<50 μg/m3) increases …”
36. The figures are in good quality.

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RR by Anonymous Referee #5 (30 Aug 2017)

ED: Reconsider after minor revisions (Editor review) (08 Sep 2017) by Xiaohong Liu

AR by Chuanfeng Zhao on behalf of the Authors (14 Sep 2017) Author's response Manuscript

ED: Publish subject to technical corrections (01 Oct 2017) by Xiaohong Liu

Dear Authors,

The manuscript has been much improved with the revision. I appreciate the efforts the authors put into revising their manuscript. I still have several technical corrections before publishing. Please make the corrections:

1. Pg2, L19, change "to" to "for".
2. Pg4, L10. Since you are talking about aerosol acting as ice nuclei, please add some references on this aspect such as:
Hoose, C. and Möhler, O.: Heterogeneous ice nucleation on atmospheric aerosols: a review of results from laboratory experiments, Atmos. Chem. Phys., 12, 9817–9854, doi:10.5194/acp-12-9817-2012, 2012.

Liu, X., Shi, X., Zhang, K., Jensen, E. J., Gettelman, A., Barahona, D., Nenes, A., and Lawson, P.: Sensitivity studies of dust ice nuclei effect on cirrus clouds with the Community Atmosphere Model CAM5, Atmos. Chem. Phys., 12, 12061–12079, doi:10.5194/acp-12-12061-2012, 2012.

3. Pg5, L15. Change "building" to "development".
4. Pg6, L16. The definitions of acronyms "PBLH" and "RH" should be done earlier since they are used on Page 5.
5. Pg7, L9. change "instant" to "instantaneous".
6. Pg8, L6. change "enter by" to "entering".
7. Pg9, L10. change "MEP" to "CMA".
8. Pg12, L17. remove "the" before "AOD".
9. Pg17, L15 and L16. "Within PBLH" should be "within PBL". You need to spell out PBL.
10. Pg20, L7. change "contributed" to "attributed".
11. Pg24, L3 and L4. "For absorbing aerosols, the slope roughly decreases with increasing particle size from coarse, mixed to fine particles..." however, is the particle size decreased instead of increased from coarse, mixed to fine particles? the slope does not decrease ( 89, 111, 104). This sentence needs to be rewritten for correction.

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AR by Chuanfeng Zhao on behalf of the Authors (03 Oct 2017) Author's response Manuscript

Short summary

This study analyzes influential factors including the aerosol type, relative humidity (RH), atmospheric boundary layer height (BLH), wind speed and direction, and aerosol vertical structure to the AOD–PM_2.5 relationship. It shows that the ratio of PM_2.5 to AOD, η, varies a lot with aerosol type. η is smaller for scattering-dominant (coarse mode) than for absorbing-dominant (fine mode) aerosol. The higher the RH (BLH), the larger (smaller) the η. η also decreases with the surface wind speed.