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New investigations on homogeneous ice nucleation: The effects of water activity and water saturation formulations

Baumgartner, Manuel; Rolf, Christian; Grooß, Jens-Uwe; Schneider, Julia; Schorr, Tobias; Möhler, Ottmar; Spichtinger, Peter; Krämer, Martina


Laboratory measurements at the AIDA cloud chamber and airborne in situ observations suggest that the homogeneous freezing thresholds at low temperatures are possibly higher than expected from the so-called “Koop line”. This finding is of importance, because the ice onset relative humidity affects the cirrus cloud coverage and, at the very low temperatures of the tropical tropopause layer, together with the number of ice crystals also the transport of water vapor into the stratosphere. Both the appearance of cirrus clouds and the amount of stratospheric water feed back to the radiative budget of the atmosphere. In order to explore the enhanced ice onset humidities, we re-examine the entire homogeneous ice nucleation process, ice onset, and nucleated crystal numbers, by means of a two-moment microphysics scheme embedded in the trajectory-based model (CLaMS-Ice) as follows: the well-understood and described theoretical framework of homogeneous ice nucleation includes certain formulations of the water activity of the freezing aerosol particles and the saturation vapor pressure of water with respect to liquid water. However, different formulations are available for both parameters. ... mehr

Verlagsausgabe §
DOI: 10.5445/IR/1000142390
Veröffentlicht am 27.01.2022
DOI: 10.5194/acp-22-65-2022
Zitationen: 9
Web of Science
Zitationen: 9
Zitationen: 9
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Meteorologie und Klimaforschung – Atmosphärische Aerosolforschung (IMK-AAF)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2022
Sprache Englisch
Identifikator ISSN: 1680-7316, 1680-7324
KITopen-ID: 1000142390
HGF-Programm 12.11.26 (POF IV, LK 01) Aerosol-Cloud-Climate-Interaction
Erschienen in Atmospheric Chemistry and Physics
Verlag European Geosciences Union (EGU)
Band 22
Heft 1
Seiten 65-91
Nachgewiesen in Web of Science
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