Diurnal variations of aerosol optical properties in the North China Plain and their influences on the estimates of direct aerosol radiative effect

Kuang, Y.; Zhao, C. S.; Tao, J. C.; Ma, N.

doi:https://doi.org/10.5194/acp-15-5761-2015

Articles | Volume 15, issue 10

https://doi.org/10.5194/acp-15-5761-2015

© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue:

Haze in China (HaChi 2009–2010)

https://doi.org/10.5194/acp-15-5761-2015

© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 15, issue 10

Research article

|

26 May 2015

Research article |

| 26 May 2015

Diurnal variations of aerosol optical properties in the North China Plain and their influences on the estimates of direct aerosol radiative effect

Y. Kuang, C. S. Zhao, J. C. Tao, and N. Ma

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Final revised paper (published on 26 May 2015)
Preprint (discussion started on 07 Jan 2015)

Interactive discussion

Status: closed

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

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RC C32: 'Review of Kuang et al.', Anonymous Referee #1, 28 Jan 2015
- AC C1264: 'Reply to referee#1', Chunsheng Zhao, 02 Apr 2015
RC C77: 'Review of Kuang et al.', Anonymous Referee #2, 03 Feb 2015
- AC C1265: 'Reply to referee#2', Chunsheng Zhao, 02 Apr 2015

Peer-review completion

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

AR by Chunsheng Zhao on behalf of the Authors (03 Apr 2015) Author's response Manuscript

ED: Referee Nomination & Report Request started (07 Apr 2015) by Veli-Matti Kerminen

RR by Anonymous Referee #1 (17 Apr 2015)

Suggestions for revision or reasons for rejection

This manuscript "Diurnal variations of aerosol optical properties in the North China Plain and their influences
on the estimates of direct aerosol radiative forcing" by Kuang et al. has clearly improved after the revisions
and most of my comments were adequately addressed. However, there is one of those comments that I would like to
discuss further. I suggested that you would look also at the diurnal pattern of AERONET-measured SSA, which you
showed in your response. I would suggest that these results are also included, or at least the main conclusions
mentioned explicitly by few sentences, in the final published version of your study. For radiative effect calculations
one needs columnar measurements of optical properties, therefore with in-situ measurements there was now a necessary
assumption that near surface optical properties go for any layers. However, AERONET measures columnar properties, so
I think it is fair to discuss also these results clearly and explicitly.

Your justification not to include these results was that there are "only about one hundred valid data points of
AERONET level 2 SSA dataset at XiangHe site in July and August ... we don’t think the AERONET dataset can faithfully
capture the morning and afternoon contrast". However, an immediate counterclaim is that then it covers a much larger
number of days than your 17 days shown in the Figure 6, for instance. Moreover, it is based on several years, so why
would not it capture true contrast, at least as faithfully as your 17 days within a single one month period?

I also took L2 AERONET data of XiangHe for July-August, day by day forming first the daily average and then the departures
of morning and afternoon measurements from this daily average. It resulted in 86 days (thus 172 data points), so five
times more than 17 days. The difference between afternoon and morning SSA at 440nm was ~0.00056, afternoon values being
slightly higher. It would be certainly nice to have much more days than 86, still in my mind it is useful to mention in
the manuscript very explicitly what type of diurnal pattern for SSA one can draw from AERONET.

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RR by Anonymous Referee #2 (24 Apr 2015)

Suggestions for revision or reasons for rejection

The authors have addressed most review comments satisfactorily. I especially thank the authors for the additional analyses and Figures presented in their response, which support their rebuttal. For example, I do not believe that OPAC is the best source of wavelength-dependent refractive indices, yet the authors' Monte-Carlo analysis demonstrates that wavelength-dependence is fairly secondary to their results.

However, there are two points that need to be clarified before the manuscript can be published.

First, I have not been able to locate the changes made in response to the following discussion:

``Comment: In the introduction, the authors motivate their study by saying that satellites only
provide one or two measurements per day, and AERONET inversions are limited to a narrow range
of solar zenith angles (page 341, line 8 to 24). The authors should be fair, and their abstract and
conclusion (after line 27 on page 355) should clearly state that according to their findings,
observing an incomplete diurnal cycle has only second-order consequences on direct radiative
effect estimates.

Response: We agree with you, and some sentences are added in the conclusions and discussions.''

If the authors could locate those changes, that would be helpful.

Second, the refractive index used for the core aerosol has changed from Seinfeld and Pandis (2006) [Discussion manuscript page 346 line 10] to Ma et al. (2012) [Revised manuscript line 181].
That change is not documented in the authors' response. Why has it been made?
It does not seem to have made large changes in the results. Is that correct?

Finally, note that there are quite a few typos, especially in the revised text. I recommend careful edition before publication.

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ED: Reconsider after minor revisions (Editor review) (28 Apr 2015) by Veli-Matti Kerminen

AR by Chunsheng Zhao on behalf of the Authors (29 Apr 2015) Author's response Manuscript

ED: Publish subject to technical corrections (04 May 2015) by Veli-Matti Kerminen

AR by Chunsheng Zhao on behalf of the Authors (05 May 2015) Author's response Manuscript

Short summary

In this paper, it is found that the diurnal variations of single scattering albedo (SSA) and asymmetry factor (g) for ambient aerosol are both evident and far different from those of dry state aerosol in the North China Plain (NCP. The diurnal changes of SSA and g have significant impacts on the estimation of daily average direct aerosol radiative effect (DARE) at the top of the atmosphere. In addition, several suggestions are proposed to improve the accurate prediction of DARE in the NCP.