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Quasi-spherical Ice in Convective Clouds

Järvinen, Emma and Schnaiter, Martin and Mioche, Guillaume and Jurkat, Tina and Voigt, Christiane and Schlager, Hans (2016) Quasi-spherical Ice in Convective Clouds. Journal of the Atmospheric Sciences. American Meteorological Society. DOI: 10.1175/JAS-D-15-0365.s1 ISSN 0022-4928

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Official URL: http://dx.doi.org/10.1175/JAS-D-15-0365.s1

Abstract

Homogeneous freezing of supercooled droplets occurs in convective systems in low and midlatitudes. This droplet-freezing process leads to the formation of a large amount of small ice particles, so-called frozen droplets, that are transported to the upper parts of anvil outflows, where they can influence the cloud radiative properties. However, the detailed microphysics and, thus, the scattering properties of these small ice particles are highly uncertain. Here, the link between the microphysical and optical properties of frozen droplets is investigated in cloud chamber experiments, where the frozen droplets were formed, grown, and sublimated under controlled conditions. It was found that frozen droplets developed a high degree of small-scale complexity after their initial formation and subsequent growth. During sublimation, the small-scale complexity disappeared, releasing a smooth and near-spherical ice particle. Angular light scattering and depolarization measurements confirmed that these sublimating frozen droplets scattered light similar to spherical particles: that is, they had angular light-scattering properties similar to water droplets. The knowledge gained from this laboratory study was applied to two case studies of aircraft measurements in midlatitude and tropical convective systems. The in situ aircraft measurements confirmed that the microphysics of frozen droplets is dependent on the humidity conditions they are exposed to (growth or sublimation). The existence of optically spherical frozen droplets can be important for the radiative properties of detraining convective outflows.

Item URL in elib:https://elib.dlr.de/107432/
Document Type:Article
Title:Quasi-spherical Ice in Convective Clouds
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Järvinen, EmmaKITUNSPECIFIED
Schnaiter, MartinKITUNSPECIFIED
Mioche, GuillaumeUniverite Clermont FerrandUNSPECIFIED
Jurkat, TinaDLR, IPAUNSPECIFIED
Voigt, ChristianeDLR, IPAUNSPECIFIED
Schlager, HansDLR, IPAUNSPECIFIED
Date:2016
Journal or Publication Title:Journal of the Atmospheric Sciences
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
DOI :10.1175/JAS-D-15-0365.s1
Publisher:American Meteorological Society
ISSN:0022-4928
Status:Published
Keywords:clouds, sphericity, ice, cirrus
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:air traffic management and operations
DLR - Research area:Aeronautics
DLR - Program:L AO - Air Traffic Management and Operation
DLR - Research theme (Project):L - Human factors and safety in Aeronautics
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics > Atmospheric Trace Species
Deposited By: Voigt, Dr.rer.nat. Christiane
Deposited On:10 Nov 2016 07:25
Last Modified:06 Sep 2019 15:27

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