Understanding aerosol–cloud interactions through modeling the development of orographic cumulus congestus during IPHEx

Duan, Yajuan; Petters, Markus D.; Barros, Ana P.

doi:https://doi.org/10.5194/acp-19-1413-2019

Articles | Volume 19, issue 3

https://doi.org/10.5194/acp-19-1413-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/acp-19-1413-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 19, issue 3

Research article

|

04 Feb 2019

Research article |

| 04 Feb 2019

Understanding aerosol–cloud interactions through modeling the development of orographic cumulus congestus during IPHEx

Yajuan Duan, Markus D. Petters, and Ana P. Barros

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Final revised paper (published on 04 Feb 2019)
Supplement to the final revised paper
Preprint (discussion started on 14 May 2018)
Supplement to the preprint

Interactive discussion

Status: closed

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

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AC1: 'Author Comment regarding a previous version of the manuscript', Yajuan Duan, 19 May 2018
RC1: 'Review of “Understanding aerosol-cloud interactions through modelling the development of orographic cumulus congestus during IPHEx”', Anonymous Referee #1, 18 Jun 2018
RC2: 'A review of the manuscript acp-2018-419 "Understanding aerosol-cloud interactions through modelling the development of orographic cumulus congestus during IPHEx"', Anonymous Referee #2, 20 Jun 2018
RC3: 'acp-2018-419 - Review of "Understanding aerosol–cloud interactions through modelling the development of orographic cumulus congestus during IPHEx"', Anonymous Referee #3, 06 Jul 2018
RC4: 'Comments on the “Understanding aerosol-cloud interactions through modelling the development of orographic cumulus congestus during IPHEx” by Duan et al.', Anonymous Referee #4, 16 Jul 2018

Peer-review completion

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

AR by Yajuan Duan on behalf of the Authors (01 Oct 2018) Manuscript

ED: Referee Nomination & Report Request started (05 Oct 2018) by Hailong Wang

RR by Anonymous Referee #4 (23 Oct 2018)

Suggestions for revision or reasons for rejection

The revision addressed most of the questions raised by the reviewers and the overall organisation of the manuscript is improved. However, there are still some questions remained ambiguous. Besides, the response letter is not well-written. The sentences are very long and redundant and sometimes bear severe grammar mistakes that one cannot follow. Therefore, I do not support the publication of the present form of the manuscript before it is carefully revised based on all comments made by the previous and current reviews.

(1) The revision is not very well-written. Some sentences are very long and difficult to understand. For example:
a. The last sentence of the abstract: “Nonetheless, the model simulations provide new constraints of the determinant factors of convective cloud formation leading to mid-day warm season rainfall in complex terrain.” I think the sentence is either incomplete or needs structural improvement.
b. Line 15-17, page 3: “The representation of physical and chemical processes related to clouds and precipitation in numerical models relies on parameterizations with varying degrees of uncertainties depending on space-time model resolution because of multiscale and complex physics, (Khairoutdinov et al., 2005; Randall et al., 2003)” The sentence is wordy and not understandable, and the comma should be period.
c. Line 32, page 19 – line 4, page 20
I would suggest splitting all sentences that exceed 3 lines, if possible.

(2) One critical comment that shared by all reviewers is that the paper did not present a clear scientific contribution. The revision still did not satisfactorily provide convincing arguments. Specifically, the scientific purpose and the deliverables of the study is very vague. What is the research question of this study? What is new? What is confirmed from this study and what is the conclusion? What is the contribution of this study? The readers should be able to obtain with ease the answers to the above questions from the paper. In the response letter, the authors answer three times regarding the significance of the work. However, the statements are either too general (i.e., point (4)) or too wordy to understand (i.e., point (3)) or both (i.e. point (5)). I can marginally get from the first two points that the model provides a new tool to study ACI that considers complexed terrain, constraints from the observations, and entrainment. I would suggest the authors use more clear statement to answer the above questions.

(3) The authors stressed more than once in the manuscript as well as in the response letter that their model can illustrate the interplay of physical and chemical processes. However, based on the model description, there is no chemical processes involved in the model. The only thing that is related to “chemistry” is that the model considers the chemical component which affects the hygroscopicity of the aerosol particles. This in no circumstances can be defined as a chemical process. It is strongly suggested that the authors remove the misleading statements that appear in the manuscript.

(4) The idea of “seeder-feeder interactions” is used quite frequently without any explanation of what it is. I suggest the author give a brief and clear description on what is the seeder and what is the feeder and how the mechanism works. Simply mentioning the name does not help to clarify the role of LLCF in rain enhancement.

(5) What is ACPI? It not defined in the manuscript.

(6) Further questions in addition to the 3rd question by Reviewer#1: In equation 8, the droplet in each bin is associated to the aerosols of its corresponding bin. However, why is the droplet number concentration only determined by the number concentration of the aerosol of the ith bin? It is quite possible that aerosol of other bins can contribute to the droplet of ith bin. I.e., droplet of same size (wet radius) can have very different dry radius.

(7) In the answer to the 1st question of reviewer#2, the authors stated that the fall speed of the droplet is < 0.1 m/s. However, this statement is not true. If the model includes drops up to 7mm (line 20, page 7), the fall speed shall easily exceed 1 m/s (Fig. 6 in Beard 1975). Therefore, the statement that the sedimentation effect is not important because “the updraft speed always exceeds fall speed” is not valid. In addition, since the parcel is rising adiabatically (i.e., the model is in Lagrangian framework), the droplet sedimentation should not be affected by the updraft.

(8) To the 3rd question by reviewer #4: no change was made in the revised manuscript.

(9) Spelling & grammar:
a. Line 32, page 2: warm-season
b. Line 26, page3: is adequate to…
c. Line 8, page 12: was used in the process-study
d. Line 1, page 20: bin microphysics
e. Line 31, page 20: parcel models
f. Line 3, page 21: aerosol-cloud interaction
g. Line 4, page 22: relationship
h. There should be space between references. i.e., Koren et al., 2008; Ramanathan et al., 2001.

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ED: Reconsider after major revisions (25 Oct 2018) by Hailong Wang

AR by Ana Barros on behalf of the Authors (16 Dec 2018)

ED: Publish as is (21 Dec 2018) by Hailong Wang

AR by Ana Barros on behalf of the Authors (02 Jan 2019) Manuscript

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Short summary

A new cloud parcel model that simulates entrainment, condensational growth, and collision–coalescence processes is presented and evaluated against airborne observations in complex terrain during IPHEx. Analysis of model simulations reveals that nonlinear interactions among turbulent dispersion, activation, and droplet growth processes modulate spectral width and explain the emergence of bimodal cloud drop spectra in aircraft measurements from different cloud regions and at different heights.