Preprints
https://doi.org/10.5194/egusphere-2023-754
https://doi.org/10.5194/egusphere-2023-754
22 May 2023
 | 22 May 2023

Technical note: Bimodal Parameterizations of in situ Ice Cloud Particle Size Distributions

Irene Bartolomé García, Odran Sourdeval, Reinhold Spang, and Martina Krämer

Abstract. The cloud particle size distribution (PSD) is a key parameter for the retrieval of micro-physical and optical properties from remote sensing instruments, which in turn are necessary for determining the radiative effect of clouds. Current representations of PSDs for ice clouds rely on parameterizations that were largely based on in situ measurements where the distribution of small ice crystals were uncertain. This makes current parameterizations deficient to simulate remote sensing observations sensitive to small ice, such as from lidar and thermal infrared instruments. In this study we fit the in situ PSDs of ice crystals from the JULIA (JÜLich In situ Aircraft data set) database, which consists of 11 campaigns covering the tropics, mid-latitudes and the Arctic, consistently processes and considered more robust in their measurements of small ice. For the fitting, we implement an established approach to PSD parameterizations, which consists in finding an adequate set of parameters for a modified gamma function after normalization of both PSD axes. These parameters are constrained to match in-situ mea surements when predicting microphysical properties from the PSDs, via a cost function minimization method. We selected the ice water content and the ice crystal number concentration, which are currently key parameters for modern satellite retrievals and model microphysics schemes. We found that a bimodal parameterization yields better results than a monomodal one. The bimodal parameterization has a lower spread for almost all ice crystal sizes over the entire range of analyzed temperatures and fits better the observations, especially for particles between 20 and about 110 μm at temperatures between −60 and −20 °C. For this temperature range, the root mean square error for the retrieved Nice is reduced from 0.36 to 0.20. This demonstrates a clear advantage to considering the bimodality of PSDs, e.g. for satellite retrievals.

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Journal article(s) based on this preprint

06 Feb 2024
Technical note: Bimodal parameterizations of in situ ice cloud particle size distributions
Irene Bartolomé García, Odran Sourdeval, Reinhold Spang, and Martina Krämer
Atmos. Chem. Phys., 24, 1699–1716, https://doi.org/10.5194/acp-24-1699-2024,https://doi.org/10.5194/acp-24-1699-2024, 2024
Short summary
Irene Bartolomé García, Odran Sourdeval, Reinhold Spang, and Martina Krämer

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-754', Anonymous Referee #1, 03 Jun 2023
  • RC2: 'Second review of Technical note: Bimodal Parameterizations of in situ Ice Cloud Particle Size Distributions', Anonymous Referee #2, 19 Jun 2023

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-754', Anonymous Referee #1, 03 Jun 2023
  • RC2: 'Second review of Technical note: Bimodal Parameterizations of in situ Ice Cloud Particle Size Distributions', Anonymous Referee #2, 19 Jun 2023

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Irene Bartolome Garcia on behalf of the Authors (28 Sep 2023)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (19 Oct 2023) by Barbara Ervens
RR by Andrew Heymsfield (28 Oct 2023)
RR by Anonymous Referee #2 (03 Nov 2023)
ED: Publish subject to minor revisions (review by editor) (07 Nov 2023) by Barbara Ervens
AR by Irene Bartolome Garcia on behalf of the Authors (30 Nov 2023)  Author's response   Author's tracked changes   Manuscript 
ED: Publish subject to technical corrections (06 Dec 2023) by Barbara Ervens
AR by Irene Bartolome Garcia on behalf of the Authors (13 Dec 2023)  Author's response   Manuscript 

Journal article(s) based on this preprint

06 Feb 2024
Technical note: Bimodal parameterizations of in situ ice cloud particle size distributions
Irene Bartolomé García, Odran Sourdeval, Reinhold Spang, and Martina Krämer
Atmos. Chem. Phys., 24, 1699–1716, https://doi.org/10.5194/acp-24-1699-2024,https://doi.org/10.5194/acp-24-1699-2024, 2024
Short summary
Irene Bartolomé García, Odran Sourdeval, Reinhold Spang, and Martina Krämer
Irene Bartolomé García, Odran Sourdeval, Reinhold Spang, and Martina Krämer

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Latest update: 18 Sep 2024
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Short summary
How many ice crystals of each size are in a cloud is a key parameter for the retrieval of cloud properties. The distribution of ice crystals is obtained from in situ measurements and used to create parameterizations that can be used when analyzing the remote sensing data. Current parameterizations are based in datasets that do not include realible measurements of small crystals, but in our study we use a dataset that includes very small ice crystals to improve these parameterizations.