Ice crystal number concentration estimates from lidar–radar satellite remote sensing – Part 1: Method and evaluation

Sourdeval, Odran; Gryspeerdt, Edward; Krämer, Martina; Goren, Tom; Delanoë, Julien; Afchine, Armin; Hemmer, Friederike; Quaas, Johannes

doi:https://doi.org/10.5194/acp-18-14327-2018

Articles | Volume 18, issue 19

https://doi.org/10.5194/acp-18-14327-2018

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

https://doi.org/10.5194/acp-18-14327-2018

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

Articles | Volume 18, issue 19

Research article

| Highlight paper

|

09 Oct 2018

Research article | Highlight paper |

| 09 Oct 2018

Ice crystal number concentration estimates from lidar–radar satellite remote sensing – Part 1: Method and evaluation

Odran Sourdeval, Edward Gryspeerdt, Martina Krämer, Tom Goren, Julien Delanoë, Armin Afchine, Friederike Hemmer, and Johannes Quaas

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Final revised paper (published on 09 Oct 2018)
Supplement to the final revised paper
Preprint (discussion started on 31 Jan 2018)

Interactive discussion

Status: closed

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

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RC1: 'Review of ACP-2018-20 ‘Ice crystal number concentration estimates from lidar-radar satellite remote sensing. Part 1: Method and evaluation’', Anonymous Referee #3, 27 Feb 2018
- AC1: 'Response to RC1', Odran Sourdeval, 17 Jul 2018
RC2: 'review comments', Anonymous Referee #1, 02 Mar 2018
- AC2: 'Response to RC1', Odran Sourdeval, 17 Jul 2018
RC3: 'Referee comments', Anonymous Referee #2, 15 Mar 2018
- AC3: 'Response to RC3', Odran Sourdeval, 17 Jul 2018
RC4: 'comment on referee #2 comments', Anonymous Referee #1, 20 Mar 2018
- AC4: 'Response to RC4', Odran Sourdeval, 17 Jul 2018
AC5: 'Combined responses with manuscript differences and supplementary materials', Odran Sourdeval, 17 Jul 2018

Peer-review completion

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

AR by Odran Sourdeval on behalf of the Authors (17 Jul 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (18 Jul 2018) by Matthias Tesche

RR by Anonymous Referee #1 (10 Aug 2018)

Suggestions for revision or reasons for rejection

General Comments:

The authors have provided thorough replies and explanations to all my comments/questions. I appreciate all the work they have invested into this process and which has provided the research community with a valuable tool. I have only a few specific comments.

Specific Comments:

1. Regarding the 2nd author comment and Fig. S3, please include SPARTICUS data in the analysis for Fig. S3. SPARTICUS (dedicated to sampling cirrus clouds) was conducted over a 6-month period with several flights per month. Some flights were downwind of the Rocky Mountains of North America while many others were over the ARM Southern Great Plains facility. This should provide a diversity of cirrus conditions and should thus provide representative sampling over continental regions. The other campaigns listed do not provide the long-term and spatially extensive sampling that SPARTICUS provides. I’m assuming that the ARM data indicated is for the year 2000 ARM campaign.

2. Regarding major comment/response #5 and Sec. 6.1, the cirrus sampled by the lidar-IR method in Mitchell et al. (2016; 2018) roughly correspond to visible optical depths (ODs) between 0.3 and 3.0. Most would probably agree that cirrus clouds that completely block the Sun’s image are not thin cirrus, and one can just make out the orb of the Sun at a cirrus OD of 1.0 (Peter Francis, private communication). That is, the Sun’s orb is not visible for OD > 1.0 approximately. Therefore, it is suggested that in Sec. 6.1, that the sentence appearing as "Lidar and thermal-infrared measurements indeed only provide the concentrations of thin cirrus or at cloud-top found at this temperature range, ..." be changed to "Lidar and thermal-infrared measurements indeed only provide the concentrations of thin-to-moderately thick cirrus or near cloud-top found at this temperature range, …". This revised sentence appears consistent with the findings of Hong and Liu (2015, J. Climate).

This reviewer agrees that OD differences in the tropical cirrus clouds sampled by the lidar-IR method vs. the DARDAR-LIM method is the most logical explanation for the relative differences in tropical N retrieved by these two methods. The fact that the two retrievals exhibit similar relative differences in N in the mid-to-high latitudes is indeed encouraging.

Referee Report: PDF

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RR by Anonymous Referee #2 (17 Aug 2018)

ED: Publish subject to technical corrections (20 Aug 2018) by Matthias Tesche

Short summary

The number concentration of ice crystals (N_i) is a key cloud property that remains very uncertain due to difficulties in determining it using satellites. This lack of global observational constraints limits our ability to constrain this property in models responsible for predicting future climate. This pair of papers fills this gap by showing and analyzing the first rigorously evaluated global climatology of N_i, leading to new information shedding light on the processes that control high clouds.