Investigating the role of dust in ice nucleation within clouds and further effects on the regional weather system over East Asia – Part 2: modification of the weather system

Su, Lin; Fung, Jimmy C. H.

doi:https://doi.org/10.5194/acp-18-11529-2018

Articles | Volume 18, issue 15

https://doi.org/10.5194/acp-18-11529-2018

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

https://doi.org/10.5194/acp-18-11529-2018

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

Articles | Volume 18, issue 15

Research article

|

15 Aug 2018

Research article |

| 15 Aug 2018

Investigating the role of dust in ice nucleation within clouds and further effects on the regional weather system over East Asia – Part 2: modification of the weather system

Lin Su and Jimmy C. H. Fung

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Final revised paper (published on 15 Aug 2018)
Preprint (discussion started on 13 Oct 2017)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Comments and Suggestions', Anonymous Referee #1, 17 Nov 2017
- AC1: 'Response to the anonymous referee', Lin Su, 12 Dec 2017
RC2: 'Review of “Investigating the role of dust in ice nucleation within clouds and further effects on the regional weather system over East Asia – Part II: modification of the weather system” by L. Su and C. H. Fung', Anonymous Referee #2, 18 Dec 2017
- AC2: 'Response to the anonymous referee', Lin Su, 22 Dec 2017

Peer-review completion

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

AR by Lin Su on behalf of the Authors (14 Jan 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (20 Feb 2018) by Corinna Hoose

RR by Anonymous Referee #2 (07 Mar 2018)

Suggestions for revision or reasons for rejection

I rated the scientific quality as poor based on my comments below. I might be wrong in my understand of the implementation of the model (in which case I would rate the scientific quality as good), but if I am correct, I believe the work needs some major revisions with new model runs

I need some more information about the implementation of this scheme before I can give any recommendations regarding this paper, and I have to admit that I have not read the entire manuscript again because I have a major concern:

In the Thompson-Eidhammer scheme it is found that an important contributor to in-situ cirrus clouds is the homogeneous freezing of deliquescent aerosols (Koop et al parameterization). This process can contribute to ice concentration of several hundreds L-1, because this freezing comes from sulfate aerosols which can have concentrations of 1-100 cm-3 (i.e. 1000-100,000 L-1). According to Su et al., homogeneous freezing of deliquescent aerosols is calculated based on aerosol concentration of 1 L-1. This means that ice crystal concentration from homogeneous freezing of deliquescent aerosols can maximum be 1 L-1, much less than what is typical (hundreds L-1).

In the conclusion, Su et al states that they find that dust has a large impact in the upper troposphere and increase in cloud ice is mainly concentrated to the mid to upper troposphere. I can see that this is the case if the background ice concentration is only 1 L-1, instead of for example 200 L-1, which you can find, due to homogeneous freezing.

Su et al also found that they had to reduce the limit for when ice freeze to 100 % RHi, due to too low ice water content. I can also see that this is the case if homogeneous freezing is not effective in their setup.

In effect, I have major concern about the findings in their paper regarding dust, if homogeneous freezing of deliquescent aerosols is not effective. I believe the dust to be found too effective compared to what is actually happening in the atmosphere.

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RR by Anonymous Referee #1 (07 Mar 2018)

ED: Reconsider after major revisions (16 Mar 2018) by Corinna Hoose

AR by Lin Su on behalf of the Authors (09 May 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (05 Jun 2018) by Corinna Hoose

RR by Anonymous Referee #2 (06 Jul 2018)

Suggestions for revision or reasons for rejection

Review

I am happy with the changes the authors have done to the homogeneous freezing of deliquescent aerosols and the results seem more reasonable. I have a few minor comments and I think the paper will be fit for publication after these comments are addressed

Introduction
Page 5, line 47: The semi-direct effect does not only have to be for aerosols (here dust) within clouds. This is the definition used in IPCC: Absorption of solar radiation by absorbing aerosols affects static stability and the surface energy budget, and may lead to an evaporation of cloud particles. I suggest rewording the definition in the paper. The semi-direct effect has an impact on cloud formation and lifetime, but the aerosols does not have to be located interstitial within the clouds.

Page 7, line 97: This is the first time hygroscopic aerosol concentration is mentioned. Below is the description of where these aerosols come from (the water friendly aerosols from Thompson-Eidhammer scheme). Instead of using “aerosol using the hygroscopic aerosol concentration” I removing “the” in front of hygroscopic.

Page 11, line 225. I suggest replacing “format” with “properties”

Page 13, line 262: I suggest replacing “fined” with “small”

Page 14, line 290: How is “dust induced” SW, LW and TOA determined. Is the SW and LW from dust an output, or do you take the difference between DUST and NO-DUST runs to determine the “dust induced” forcings?

Page 15, line 342: What is meant by “relative slight” ?

Page 17, lines 378-382. This sentence is long. I suggest breaking it up into two sentences.

Page 21, line 499: This sentence is difficult to understand. Please rephrase.

Page 23, line 542: Should this line be deleted?

Page 24, line 577: Please rephrase sentence.

Page 24, line 583: As mentioned earlier, the semi direct-effect does not only act on particles within cloud, but in the entire atmosphere.

Page 25, line 598: Do you ever really show a redistribution of water vapor? You show changes in LWC and IWC and the K-index. I would add a sentence or two on how you infer the changes in water vapor based on the other parameters you have discussed.

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ED: Publish subject to minor revisions (review by editor) (20 Jul 2018) by Corinna Hoose

AR by Lin Su on behalf of the Authors (25 Jul 2018) Author's response Manuscript

ED: Publish subject to technical corrections (02 Aug 2018) by Corinna Hoose

AR by Lin Su on behalf of the Authors (03 Aug 2018) Author's response Manuscript

Short summary

By applying an updated version of WRF-Chem, we aim to investigate the full effects of dust, including direct, semi-direct, and indirect effects, on the regional weather system over East Asia during a dust-intensive period. This is the first study to document the full effects of dust during a typical dust-intensive period over East Asia by applying an online coupled regional numerical model.