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Redistribution of ice nuclei between cloud and rain droplets: Parameterization and application to deep convective clouds

Paukert, M. 1; Hoose, Corinna ORCID iD icon 1; Simmel, M.
1 Institut für Meteorologie und Klimaforschung (IMK), Karlsruher Institut für Technologie (KIT)


In model studies of aerosol-dependent immersion freezing in clouds, a common assumption is that each ice nucleating aerosol particle corresponds to exactly one cloud droplet. In contrast, the immersion freezing of larger drops—“rain”—is usually represented by a liquid volume-dependent approach, making the parameterizations of rain freezing independent of specific aerosol types and concentrations. This may lead to inconsistencies when aerosol effects on clouds and precipitation shall be investigated, since raindrops consist of the cloud droplets—and corresponding aerosol particles—that have been involved in drop-drop-collisions. Here we introduce an extension to a two-moment microphysical scheme in order to account explicitly for particle accumulation in raindrops by tracking the rates of selfcollection, autoconversion, and accretion. This provides a direct link between ice nuclei and the primary formation of large precipitating ice particles. A new parameterization scheme of drop freezing is presented to consider multiple ice nuclei within one drop and effective drop cooling rates. In our test cases of deep convective clouds, we find that at altitudes which are most relevant for immersion freezing, the majority of potential ice nuclei have been converted from cloud droplets into raindrops. ... mehr

Verlagsausgabe §
DOI: 10.5445/IR/1000067325
Veröffentlicht am 16.03.2018
DOI: 10.1002/2016MS000841
Zitationen: 13
Web of Science
Zitationen: 13
Zitationen: 15
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Meteorologie und Klimaforschung – Forschungsbereich Troposphäre (IMK-TRO)
KIT-Zentrum Klima und Umwelt (ZKU)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2017
Sprache Englisch
Identifikator ISSN: 1942-2466
KITopen-ID: 1000067325
HGF-Programm 12.01.01 (POF III, LK 01) Clouds in a pertubed atmosphere
Erschienen in Journal of advances in modeling earth systems
Verlag American Geophysical Union (AGU)
Band 9
Heft 1
Seiten 514-535
Schlagwörter ice nucleation, rain freezing, convetive clouds, microphysics
Nachgewiesen in Dimensions
Web of Science
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