Impact of aerosols on ice crystal size

Zhao, Bin; Liou, Kuo-Nan; Gu, Yu; Jiang, Jonathan H.; Li, Qinbin; Fu, Rong; Huang, Lei; Liu, Xiaohong; Shi, Xiangjun; Su, Hui; He, Cenlin

doi:https://doi.org/10.5194/acp-18-1065-2018

Articles | Volume 18, issue 2

https://doi.org/10.5194/acp-18-1065-2018

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

https://doi.org/10.5194/acp-18-1065-2018

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

Articles | Volume 18, issue 2

Research article

|

26 Jan 2018

Research article |

| 26 Jan 2018

Impact of aerosols on ice crystal size

Bin Zhao, Kuo-Nan Liou, Yu Gu, Jonathan H. Jiang, Qinbin Li, Rong Fu, Lei Huang, Xiaohong Liu, Xiangjun Shi, Hui Su, and Cenlin He

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Final revised paper (published on 26 Jan 2018)
Supplement to the final revised paper
Preprint (discussion started on 26 Jul 2017)
Supplement to the preprint

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'comments on "A water vapor modulated aerosol impact on ice crystal size" by Zhao, et. al.', Anonymous Referee #1, 19 Aug 2017
- AC1: 'Response to Anonymous Referee #1', Bin Zhao, 08 Nov 2017
RC2: 'review of "A water vapor modulated aerosol impact on ice crystal size"', Anonymous Referee #2, 28 Aug 2017
- AC2: 'Response to Anonymous Referee #2', Bin Zhao, 08 Nov 2017

Peer-review completion

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

AR by Bin Zhao on behalf of the Authors (08 Nov 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (08 Nov 2017) by Qiang Fu

RR by Anonymous Referee #1 (14 Nov 2017)

RR by Anonymous Referee #2 (25 Nov 2017)

Suggestions for revision or reasons for rejection

General Comments:

I have gone over all of the author responses to my comments, and am happy to say that all have been addressed very well. The authors have done an excellent job at revising their paper, which reflects a considerable amount of additional work (e.g. the improvements on modeling). As noted in the first review, this appears to be the first combined observational-modeling study showing the impact of aerosols on cirrus cloud microphysics under various meteorological conditions. The conceptual framework of the paper is now greatly improved, and I suspect this paper will be widely referenced in regards to cirrus cloud-aerosol-radiation interactions. There are just a few outstanding issues that should be addressed, as described below. Congratulations to the authors for this significant advancement in our understanding.

Major Comments:
1) Page 8, line 33: Different investigators use different formula for calculating Rei; which equation is used here?

2) Page 16, lines 11-12, and Fig. 5 in general: Since the model has been improved to more closely mimic natural processes now (and predicted and observed Rei agree fairly well), it would be interesting to know what fraction of INP result in an ice crystal for aerosol number concentration > 300 cm-3 (when nearly all ice crystals are produced by heterogeneous ice nucleation). This information would be useful for comparing with other cirrus cloud modeling studies.

Combining deposition and immersion INP together, the INP to aerosol ratio is 1:10,000. For an aerosol concentration of 300 cm-3, the combined INP concentration should be 0.03 cm-3, or 30 L-1. But Fig. 5b relates this INP concentration to an ice crystal concentration (Ni) of ~ 300 L-1. It seems that either I have made a mistake in this calculation (or assumed something incorrect), or the combined INP-to-aerosol ratio should be 1:1000 to account for an Ni of 300 L-1 (assuming all INP produce an ice crystal).

Minor Comments:
1) Page 4, lines 12-13: Might be more accurate to say that the DARDAR Rei retrievals, corrected for the crystal habit assumption used here, lie mostly between 10 and 80 microns.

2) Page 12, line 29: dcreases => decreases

Referee Report: PDF

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ED: Publish subject to technical corrections (11 Dec 2017) by Qiang Fu

AR by Bin Zhao on behalf of the Authors (16 Dec 2017) Author's response Manuscript

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Short summary

The interactions between aerosols and ice clouds represent one of the largest uncertainties among anthropogenic forcings on climate change. We find that the responses of ice crystal effective radius, a key parameter determining ice clouds' net radiative effect, to aerosol loadings are modulated by water vapor amount and vary from a significant negative correlation in moist conditions (consistent with the “Twomey effect” for liquid clouds) to a strong positive correlation in dry conditions.