Measuring ice- and liquid-water properties in mixed-phase cloud layers at the Leipzig Cloudnet station

Bühl, Johannes; Seifert, Patric; Myagkov, Alexander; Ansmann, Albert

doi:https://doi.org/10.5194/acp-16-10609-2016

Articles | Volume 16, issue 16

https://doi.org/10.5194/acp-16-10609-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

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https://doi.org/10.5194/acp-16-10609-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 16, issue 16

Research article

|

26 Aug 2016

Research article |

| 26 Aug 2016

Measuring ice- and liquid-water properties in mixed-phase cloud layers at the Leipzig Cloudnet station

Johannes Bühl, Patric Seifert, Alexander Myagkov, and Albert Ansmann

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Final revised paper (published on 26 Aug 2016)
Preprint (discussion started on 27 Jan 2016)

Interactive discussion

Status: closed

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

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RC1: 'Comments', Anonymous Referee #1, 24 Feb 2016
RC2: 'Review of “Relation between ice and liquid water mass in mixed-phase cloud layers measured with Cloudnet” by Johannes Bühl, Patric Seifert, Alexander Myagkov, and Albert Ansmann', Anonymous Referee #2, 22 Apr 2016
RC3: 'Review: Bühl et al., Relation between ice and liquid water mass in mixed-phase cloud layers measured with Cloudnet', Anonymous Referee #3, 28 Apr 2016
AC1: 'Author's response to reviewer comments', Johannes Bühl, 17 Jun 2016

Peer-review completion

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

AR by Johannes Bühl on behalf of the Authors (23 Jun 2016) Author's response Manuscript

ED: Referee Nomination & Report Request started (29 Jun 2016) by Jianping Huang

RR by Anonymous Referee #1 (11 Jul 2016)

RR by Anonymous Referee #2 (15 Jul 2016)

Suggestions for revision or reasons for rejection

Review of “Relation between ice and liquid water mass in mixed-phase cloud layers measured with Cloudnet” by Johannes Bühl, Patric Seifert, Alexander Myagkov, and Albert Ansmann

I thank the authors for enhancing the manuscript. However, I still have concerns regarding three of the major issues I raised. Remarkably, the authors rejected in particular comments which involve more effort than changing some lines in the manuscript.

Major comments

Vertical air motion: The authors have to provide more details in L 153/154: How much averaging is required to get rid of vertical air motion? Are there any references supporting that? Isn’t that in opposition to their statement in the introduction: “Vertical motions keep mixed-phase clouds alive by activating aerosol particles to cloud droplets…”. Why did the authors not apply the Shupe et al 2008 algorithm for detecting vertical air motion? The authors seem to know the method since the article is in their references. At least the authors should mention the issue more clearly when analyzing the Doppler velocity and introducing the static ice flux. Furthermore, the authors often use the term ‘fall velocity’ when they actually mean ‘Doppler velocity’ (e.g. Fig 8b and corresponding discussion). Please go through the manuscript in order to use them correctly.

Z-IWC relation: The authors responded: “We consider the Hogan retrieval as the best that is currently available.” but do not point out why they think Hogan’s method is best. Hogan et al (2006) assumed the mass-size relation of Brown and Francis (1995) which is based on a study by Locatelli and Hobbs (1974). They developed the mass-size relation for “aggregates of unrimed bullets, columns and side-planes”. Since this study is targeting pristine ice particles, how can a mass size relation for aggregates be used? Moreover, Hogan assumed the median volume diameter of the particle size distribution to be between 0.2 and 3 mm. Is that in agreement with the expected size of the pristine particles? I would recommend to apply 2-3 other Z-IWC relations in order to investigate whether this changes the overall results. I expect this won't change the results, but give a better feeling for the uncertainties.

LWP retrieval: I still think that a radiometer retrieval would be better suited to get LWP if it is offset corrected during clear sky periods. This would correct not only for water vapor, but also for potential calibration offsets. Since a radiometer is part of the standard Cloudnet set up I do not see why this should limit the applicability of the approach to other data sets. Did the authors actually compare LWP values of the radiometer and the adiabatic approach to each other?

Minor comments

Cloud misclassification: The authors responded that they estimate the accuracy of their cloud classification to be around 15% (I hope that this is actually the inaccuracy!). I would suggest to mention this in the manuscript.

Pristine particles: I would suggest that the authors point out in section 4.2 more clearly why the data shows that the observed particles are pristine. In their response to my corresponding comment, the authors points this out more clearly than in section 4.2.

Static lifetime index: ‘static’ is not used consistently in the manuscript. e.g. Section 4.4 and Figure 10.

L 147: I do not understand this statement, how is ‘quality’ quantified?

L204: This calibration is 1) component based (i.e. theoretical) and 2) for a different radar.

L 221: I’m surprised that the authors use such a static formula. Don’t the authors use the standard MIRA moments which finds the hydrometeor peak in the Doppler spectrum?

L255 fall velocities are decreased in 8b, but enhanced in 8d for the highest temperature bin?

Figure 8: Is it possible that different temperature bins have been used in Figure 8a and c (b and d)?

L 292/293: A ‘future’ approach published in 2010? Please rephrase.

L 298: If the IWC uncertainty is one magnitude, how can the uncertainty of IWC/LWC be one magnitude as well?

L 295 & 304: Isn’t the statement in line 295 “Assuming that particles directly below the mixed-phase layer have the same properties as within the layer…” (i.e. the authors assume static conditions) in opposition to Line 304 “ice formation is a dynamic process“?

L 301: Do the authors really mean ‘error’? maybe ‘variability’?

L 308: v -> v_CB?

Autors' response to reviewer #3: I noticed that the authors mentioned a minimum time span for a cloud case of 15 min, but according to the manuscript (L 155) it is 20 minutes.

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ED: Publish as is (18 Jul 2016) by Jianping Huang

AR by Johannes Bühl on behalf of the Authors (28 Jul 2016) Author's response Manuscript

Short summary

We probe thin layered clouds with remote sensing instruments from ground in order to get insight into atmospheric processes like the formation of rain or snow. We think that the findings of our work can be used to improve climate and weather simulations. The present paper presents a new technique that can be used to detect the shape, fall speed and mass of ice particles falling from layered clouds. With such information the impact of cloud ice, e.g., on the lifetime of a cloud, can be estimated.