Quantifying the aerosol effect on droplet size distribution at cloud top

Hernández Pardo, Lianet; Toledo Machado, Luiz Augusto; Amore Cecchini, Micael; Sánchez Gácita, Madeleine

doi:https://doi.org/10.5194/acp-19-7839-2019

Articles | Volume 19, issue 11

https://doi.org/10.5194/acp-19-7839-2019

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

https://doi.org/10.5194/acp-19-7839-2019

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

Articles | Volume 19, issue 11

Research article

|

12 Jun 2019

Research article |

| 12 Jun 2019

Quantifying the aerosol effect on droplet size distribution at cloud top

Lianet Hernández Pardo, Luiz Augusto Toledo Machado, Micael Amore Cecchini, and Madeleine Sánchez Gácita

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Final revised paper (published on 12 Jun 2019)
Preprint (discussion started on 05 Dec 2018)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Review of acp-2018-1087', Anonymous Referee #2, 02 Jan 2019
- AC1: 'Response to Anonymous Referee #2', Lianet Hernández Pardo, 28 Mar 2019
RC2: 'Review of Pardo et al.', Anonymous Referee #1, 03 Jan 2019
- AC2: 'Response to Anonymous Referee #1', Lianet Hernández Pardo, 28 Mar 2019

Peer-review completion

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

AR by Lianet Hernández Pardo on behalf of the Authors (25 Apr 2019) Author's response Manuscript

ED: Referee Nomination & Report Request started (26 Apr 2019) by Barbara Ervens

RR by Anonymous Referee #1 (15 May 2019)

Suggestions for revision or reasons for rejection

The revised manuscript by Pardo et al. significantly extends the original model analysis by more careful consideration of the aerosol size distribution, particle depletion, entrainment, etc. This does make a much stronger case to support their conclusions, even though the basic modelling framework is still very simplified.

The previous review comments are addressed by the revised manuscript, but I’d like to ask the Authors to elaborate a little bit on the selection of the (new) ranges for the aerosol concentrations and other distribution parameters. My point is, that for the new bin treatment, the selected aerosol concentrations are quite high across the board. At the same time, the Authors imply that the lower concentrations used for the less accurate bulk method, which are still in the range of several hundreds per cc, were not enough to produce clouds with the bin method (where activation scavenging can be described more realistically). Does this happen in combination with the low-end mode mean diameters and STD, or is there some other reason? Would this suggest that more carefully selected ranges for the distribution parameters (other than the particle number) would alleviate this issue? Please elaborate a bit on the choices you make, as the explanation in Section 3 (e.g. page 6, line 8 onwards) is a bit vague.

As a more minor note, I feel a bit uneasy with statements like “These results show that the study of the aerosol-cloud interaction must include the parameters describing aerosol properties, such as the size distribution, at least for r̄ a ≤ 0.08 μm.” in the discussion section, as it seems to suggests that studies on aerosol-cloud interactions wouldn’t consider the size distribution shape. This generally is not the case especially with contemporary microphysical models. Please consider rewording this accordingly.

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ED: Publish subject to minor revisions (review by editor) (15 May 2019) by Barbara Ervens

Dear authors,

I have received additional comments by Referee #1 (see below). Please address them in a revised manuscript.

Best regards,
Barbara Ervens

-----------------------
Referee #1

The revised manuscript by Pardo et al. significantly extends the original model analysis by more careful consideration of the aerosol size distribution, particle depletion, entrainment, etc. This does make a much stronger case to support their conclusions, even though the basic modelling framework is still very simplified.

1) The previous review comments are addressed by the revised manuscript, but I’d like to ask the Authors to elaborate a little bit on the selection of the (new) ranges for the aerosol concentrations and other distribution parameters.
My point is, that for the new bin treatment, the selected aerosol concentrations are quite high across the board. At the same time, the Authors imply that the lower concentrations used for the less accurate bulk method, which are still in the range of several hundreds per cc, were not enough to produce clouds with the bin method (where activation scavenging can be described more realistically).
- Does this happen in combination with the low-end mode mean diameters and STD, or is there some other reason?
- Would this suggest that more carefully selected ranges for the distribution parameters (other than the particle number) would alleviate this issue?
Please elaborate a bit on the choices you make, as the explanation in Section 3 (e.g. page 6, line 8 onwards) is a bit vague.

2) As a more minor note, I feel a bit uneasy with statements like “These results show that the study of the aerosol-cloud interaction must include the parameters describing aerosol properties, such as the size distribution, at least for r̄ a ≤ 0.08 μm.” in the discussion section, as it seems to suggests that studies on aerosol-cloud interactions wouldn’t consider the size distribution shape. This generally is not the case especially with contemporary microphysical models. Please consider rewording this accordingly.

Hide

AR by Lianet Hernández Pardo on behalf of the Authors (22 May 2019) Author's response Manuscript

ED: Publish subject to technical corrections (23 May 2019) by Barbara Ervens

AR by Lianet Hernández Pardo on behalf of the Authors (23 May 2019) Author's response Manuscript

Short summary

This work analyzes the effects of changes in the environmental aerosol population on Amazonian clouds. The results confirm that the clouds can be very sensitive to changes in the aerosol properties, but the relative importance of each property is variable and depends on the values of the other aerosol characteristics, especially aerosol size. This is controlled by the degree to which the cloud mixes with the surrounding air and by the efficiency with which aerosols are consumed by droplets.