A study of the impact of synoptic weather conditions and water vapor on aerosol–cloud relationships over major urban clusters of China

Kourtidis, K.; Stathopoulos, S.; Georgoulias, A. K.; Alexandri, G.; Rapsomanikis, S.

doi:https://doi.org/10.5194/acp-15-10955-2015

Articles | Volume 15, issue 19

https://doi.org/10.5194/acp-15-10955-2015

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

https://doi.org/10.5194/acp-15-10955-2015

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

Articles | Volume 15, issue 19

Research article

|

02 Oct 2015

Research article |

| 02 Oct 2015

A study of the impact of synoptic weather conditions and water vapor on aerosol–cloud relationships over major urban clusters of China

K. Kourtidis, S. Stathopoulos, A. K. Georgoulias, G. Alexandri, and S. Rapsomanikis

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Final revised paper (published on 02 Oct 2015)
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Preprint (discussion started on 18 May 2015)
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Interactive discussion

Status: closed

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

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RC C3188: 'Review of "A study of the impact of synoptic weather conditions and water vapor on aerosol-cloud relationships over major urban clusters of China" by Kourtidis et al', Anonymous Referee #1, 03 Jun 2015
- AC C4860: 'Authors response to comments by Referee #1', Konstantinos Kourtidis, 14 Jul 2015
RC C4974: 'Comments on "A study of the impact of synoptic weather conditions and water vapor on aerosol-cloud relationships over major urban clusters of China by Kourtidis et al."', Anonymous Referee #2, 16 Jul 2015
- AC C5213: 'Authors response to comments by Referee #2', Konstantinos Kourtidis, 27 Jul 2015

Peer-review completion

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

AR by Konstantinos Kourtidis on behalf of the Authors (28 Jul 2015) Author's response

ED: Referee Nomination & Report Request started (19 Aug 2015) by Evangelos Gerasopoulos

RR by Anonymous Referee #1 (01 Sep 2015)

Suggestions for revision or reasons for rejection

**** General comments ****

Kourtidis et al. have improved the clarity of their paper.
I recommend publication after the authors have considered the comments below.

**** Specific comments ****

** Extension to “regions where AOD and WV have opposite seasonal variations” [p1.14, p4.265, p7.369] **
The authors have now clarified their extrapolation in response to my previous review.
A further thing to consider is that over a hypothetical region where AOD and WV have opposite seasonal variations, the seasonal effect may not only
(a) weaken a positive AOD-CC relationship (underestimation of the “AOD impact on CC”, as mentioned by the authors),
but may actually
(b) lead to a negative AOD-CC relationship (i.e. cause an inverse relationship to be found).
The authors may like to mention this second possibility (b).

** Testing whether “there is no large systematic AOD increase at increased WV” [p4.302, p7.389] **
Apologies for the typo in my previous review.
You interpreted correctly that I intended to say “a more helpful figure would be to plot a line of AOD vs WV for different CC bins”.
I have two comments about the current version of the manuscript:

(a) I am still not convinced that “if Fig. 5 does suggest that for small bins of CC, there is no large increase in WV as AOD increases, it does also suggest, viewed from a different perspective, that for small bins of CC, there is no large increase in AOD as WV increases” [authors’ response].
It would of course be true to say that “if there is no correlation between WV and AOD there is no correlation between AOD and WV”, or “if there is only a weak correlation between WV and AOD there is only a weak correlation between AOD and WV”.
However, “linear correlation” is not the measure under consideration in either Fig. 5 or the text.
For a given CC bin and SLP regime, even if WV only increases by a small percentage as AOD increases, it is still possible that AOD could increase by a large percentage as WV increases.
You can test whether or not this is the case by plotting AOD vs WV for different CC bins (or AOD for different WV and CC bins).

(b) Even if you do find that (i) for small bins of CC (and a given SLP regime) there is no large increase in AOD as WV increases it does not follow that (ii) “there is no large systematic AOD increase at increased WV”.
Statement (i) has the clarification that CC and SLP have been controlled for; statement (ii), a more general statement, does not have this clarification.
(Indeed, if CC is not controlled for, Fig. 2b suggests that positive WV-AOD relationships often exist, indicated by the fact that WV=8cm line only starts at AOD=0.7.)

** Introduction: semi-direct effect [p1.37] **
The sentence “Absorption in the atmosphere, by perturbing the vertical temperature structure, may impact also clouds” is potentially misleading, as it could be (mis)read to imply that the absorption occurs via perturbation of the vertical temperature structure (rather than vice versa).
It would be clearer to write:
“Absorption in the atmosphere may impact also clouds, by perturbing the vertical temperature structure”.

** Data and methods: Costantino and Bréon (2013) [p3.122] **
Please check whether the Costantino and Bréon (ACPD, 2013) reference at p3.122 is accurate.
As far as I can tell, Costantino and Bréon (2013) neither (a) use aerosol index nor (b) investigate aerosol-cloud interactions - they actually focus on the direct radiative effect.
Hence I suggest deleting this reference from the paper.

**** Technical corrections ****

- A large part of the sentence starting at p3.138 is repeated almost exactly word-for-word at p3.195. Consider rewriting one of these occurrences.

- Gryspeerdt et al. (2015) reference: delete “Discuss.”, and correct pagination to 7557-7570.

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ED: Reconsider after minor revisions (Editor review) (02 Sep 2015) by Evangelos Gerasopoulos

AR by Konstantinos Kourtidis on behalf of the Authors (14 Sep 2015) Author's response Manuscript

ED: Publish as is (14 Sep 2015) by Evangelos Gerasopoulos

AR by Konstantinos Kourtidis on behalf of the Authors (15 Sep 2015)

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Short summary

The impact of aerosols on cloud cover (CC) under the influence of water vapor is studied using a decade of satellite observations. Water vapor is found to have a stronger impact on CC than aerosols. The water vapor impact shows that the hydrological cycle interferes with the aerosol climatic impact, and we need to improve our understanding of this interference.