Retrieving ice-nucleating particle concentration and ice multiplication factors using active remote sensing validated by in situ observations

Wieder, Jörg; Ihn, Nikola; Mignani, Claudia; Haarig, Moritz; Bühl, Johannes; Seifert, Patric; Engelmann, Ronny; Ramelli, Fabiola; Kanji, Zamin A.; Lohmann, Ulrike; Henneberger, Jan

doi:https://doi.org/10.5194/acp-22-9767-2022

Articles | Volume 22, issue 15

https://doi.org/10.5194/acp-22-9767-2022

© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/acp-22-9767-2022

© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 22, issue 15

Research article

|

01 Aug 2022

Research article |

| 01 Aug 2022

Retrieving ice-nucleating particle concentration and ice multiplication factors using active remote sensing validated by in situ observations

Jörg Wieder, Nikola Ihn, Claudia Mignani, Moritz Haarig, Johannes Bühl, Patric Seifert, Ronny Engelmann, Fabiola Ramelli, Zamin A. Kanji, Ulrike Lohmann, and Jan Henneberger

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Final revised paper (published on 01 Aug 2022)
Preprint (discussion started on 26 Jan 2022)

Interactive discussion

Status: closed

RC1:
'Comment on acp-2022-67', Anonymous Referee #1, 21 Feb 2022

Please see attached review for my full comments.

Citation: https://doi.org/10.5194/acp-2022-67-RC1
- AC1: 'Reply on RC1', Jörg Wieder, 05 Jun 2022
  
  The comment was uploaded in the form of a supplement: https://acp.copernicus.org/preprints/acp-2022-67/acp-2022-67-AC1-supplement.pdf
  
  Citation: https://doi.org/10.5194/acp-2022-67-AC1
RC2:
'Comment on acp-2022-67', Anonymous Referee #2, 30 Apr 2022
Review for Wieder et al., “Retrieving ice nucleating particle concentration and ice multiplication factors using active remote sensing validated by in situ observations”, submitted to Atmospheric Chemistry & Physics

This manuscript presents a method to retrieve ice-nucleating particle (INP) concentrations using a polarization Raman lidar and a Ka-band cloud radar as well as ice multiplication factors due to secondary ice production in orographic mixed-phase clouds. The retrievals were compared against in situ observations derived from a tethered balloon system at two locations: the WFJ and WOP sites at different altitudes during the RACELETS field campaign in the Swiss Alps.

Retrievals of INP concentrations and ice multiplication are both extremely poorly constrained and valuable for better constraining cloud properties. The study is thus well-motivated and using tethered balloons for ice crystal number concentration is advantageous compared to aircraft in situ probe measurements because they don’t suffer from ice crystal shattering effects. However, details describing the methodology and a clear disclosure of assumptions and quantification of limitations is lacking. Specific comments follow.

The method is not described in sufficient detail. This is especially important given the large number of assumptions that need to be made in the retrievals. For example, the method to retrieve the INP number concentration is appears to use the various INP concentrations, but not a single equation for any of the parameterizations appears in the manuscript. The same goes for the ICNC retrieved by the radar under the assumption of a particular ice crystal size distribution which was not described.

Error quantification is almost nonexistent in this work.

Why does the lidar almost always overestimate the in situ observations at the WFJ site? I couldn’t find an explanation for this.

For the non-expert in in situ measurements, why does the ambient air need to be heated to 46C in the inlet?
Citation: https://doi.org/10.5194/acp-2022-67-RC2
- AC2: 'Reply on RC2', Jörg Wieder, 05 Jun 2022
  
  The comment was uploaded in the form of a supplement: https://acp.copernicus.org/preprints/acp-2022-67/acp-2022-67-AC2-supplement.pdf
  
  Citation: https://doi.org/10.5194/acp-2022-67-AC2

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload

AR by Jörg Wieder on behalf of the Authors (05 Jun 2022) Author's response Author's tracked changes Manuscript

ED: Publish as is (21 Jun 2022) by Anne Perring

AR by Jörg Wieder on behalf of the Authors (21 Jun 2022)

Post-review adjustments

AA: Author's adjustment | EA: Editor approval

AA by Jörg Wieder on behalf of the Authors (20 Jul 2022) Author's adjustment Manuscript

EA: Adjustments approved (24 Jul 2022) by Anne Perring

Short summary

Ice formation and its evolution in mixed-phase clouds are still uncertain. We evaluate the lidar retrieval of ice-nucleating particle concentration in dust-dominated and continental air masses over the Swiss Alps with in situ observations. A calibration factor to improve the retrieval from continental air masses is proposed. Ice multiplication factors are obtained with a new method utilizing remote sensing. Our results indicate that secondary ice production occurs at temperatures down to −30 °C.