Intra-annual variations of regional aerosol optical depth, vertical distribution, and particle types from multiple satellite and ground-based observational datasets

Zhao, Bin; Jiang, Jonathan H.; Diner, David J.; Su, Hui; Gu, Yu; Liou, Kuo-Nan; Jiang, Zhe; Huang, Lei; Takano, Yoshi; Fan, Xuehua; Omar, Ali H.

doi:https://doi.org/10.5194/acp-18-11247-2018

Articles | Volume 18, issue 15

https://doi.org/10.5194/acp-18-11247-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/acp-18-11247-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 18, issue 15

Research article

|

13 Aug 2018

Research article |

| 13 Aug 2018

Intra-annual variations of regional aerosol optical depth, vertical distribution, and particle types from multiple satellite and ground-based observational datasets

Bin Zhao, Jonathan H. Jiang, David J. Diner, Hui Su, Yu Gu, Kuo-Nan Liou, Zhe Jiang, Lei Huang, Yoshi Takano, Xuehua Fan, and Ali H. Omar

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Final revised paper (published on 13 Aug 2018)
Preprint (discussion started on 12 Apr 2018)

Interactive discussion

Status: closed

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

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RC1: 'Comments to "Intra-annual variations of regional aerosol optical depth, vertical distribution, and particle types from multiple satellite and ground-based observational datasets"', Anonymous Referee #1, 08 May 2018
- AC1: 'Response to reviewer 1', Bin Zhao, 12 Jun 2018
RC2: 'Review of Zhao et al. for ACP', Anonymous Referee #2, 11 May 2018
- AC2: 'Response to reviewer 2', Bin Zhao, 12 Jun 2018

Peer-review completion

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

AR by Bin Zhao on behalf of the Authors (12 Jun 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (25 Jun 2018) by Xiaohong Liu

RR by Anonymous Referee #2 (23 Jul 2018)

Suggestions for revision or reasons for rejection

Summary: This study examines the spatial-temporal variability of both total AOD and aerosol vertical profile over three populous regions.

Overall comments: This paper is much improved compared to the previous versions. The authors have satisfactorily answered most, if not all, of the reviewers’ comments. I am happy to see better explanations/interpretations for the observed patterns, including references where possible.

1) Lines 12-13; I do not see how the two phrases are related. Short lifetimes may create aerosol “blobs” that are highly variable, but don’t see how that causes climatic effects. Suggest just removing the “relatively short times” and say. “Understanding the intra-annual variations in aerosol loading and vertical profile is important for assessing both climatic and health effects.”
2) Lines 22-28: Is a run-on sentence. I can’t follow the logic.
3) Why does the abstract not mention the interesting conclusion that the sum of low + high layers in CALIPSO do not equal MODIS or MISR, and that the seasonal patterns are different?

4) You convinced me that the sampling of MODIS/MISR gridded data (whether CALIPSO curtain or MODIS swath) does not significantly impact conclusions of seasonal variability. However, I am still uncomfortable with the use of L2 data for some datasets (CALIPSO, AERONET, PM2.5) and L3 gridded data (MODIS/MISR) for others. I would be interested in seeing more direct comparisons at the measurement/retrieval level. But maybe that is a future study.

I also have a few minor corrections/concerns.
1) Line 47. What do you mean by aerosol components? I think you mean different aerosol types (e.g. size/shape/composition/source).
2) Line 89: Suggest using “following our previous study… “
3) Lines 107- (for MISR) and lines 124- (for MODIS). Is there any issue about using 0.5° product for MISR, 1° product for MODIS? Also which version of Level 2 MISR product goes into F15 Level 3 MISR product? Note that the uncertainties (lines 112, 126) as compared to AERONET are from Level 2 (not Level 3) .
4) Lines 135-136: I wonder is there any uncertainty in aerosol “type” determination, and whether that has effect on assigning lidar ratios and thus AODs below and above 800 m. I think it warrants a sentence or two.
5) Line 177: Remove extra “N” in AERONET
6) Line 261: Is daily mean AOD 10% larger in all three regions? Line 262: I am not happy with the sentence. Remember, L3 MODIS data 1°x1° have not been validated with AERONET.
7) Lines 283: I am not going to look for them now, but there are definitely surface visibility studies (e.g. IMPROVE network) that compare horizontal extinction with PM2.5.
8) Lines 310-315. I don’t think I understand this discussion.
9) Line 446-452. I find these sentences unnecessary and outside the scope of everything we just learned. Just put the references in the previous sentence (line 445), and go straight to line 452. Leaves the door open for any kind of next steps.

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ED: Publish subject to technical corrections (27 Jul 2018) by Xiaohong Liu

AR by Bin Zhao on behalf of the Authors (02 Aug 2018) Manuscript

Short summary

We combine satellite-borne and ground-based observations to investigate the intra-annual variations of regional aerosol column loading, vertical distribution, and particle types. Column aerosol optical depth (AOD), as well as AOD > 800 m, peaks in summer/spring. However, AOD < 800 m and surface PM_2.5 concentrations mostly peak in winter. The aerosol intra-annual variations differ significantly according to aerosol types characterized by different sizes, light absorption, and emission sources.