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| Titel |
Time-dependent freezing rate parcel model |
| VerfasserIn |
G. Vali, J. R. Snider |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 4 ; Nr. 15, no. 4 (2015-02-25), S.2071-2079 |
| Datensatznummer |
250119460
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| Publikation (Nr.) |
 copernicus.org/acp-15-2071-2015.pdf |
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| Zusammenfassung |
| The time-dependent freezing rate (TDFR) model here described represents the
formation of ice particles by immersion freezing within an air parcel. The
air parcel trajectory follows an adiabatic ascent and includes a period in
time when the parcel remains stationary at the top of its ascent. The
description of the ice nucleating particles (INPs) in the air parcel is taken
from laboratory experiments with cloud and precipitation samples and is
assumed to represent the INP content of the cloud droplets in the parcel.
Time dependence is included to account for variations in updraft velocity and
for the continued formation of ice particles under isothermal conditions. The
magnitudes of these factors are assessed on the basis of laboratory
measurements. Results show that both factors give rise to three-fold variations in ice concentration for a realistic range of the input
parameters. Refinements of the parameters specifying time dependence and INP
concentrations are needed to make the results more specific to different
atmospheric aerosol types. The simple model framework described in this paper
can be adapted to more elaborate cloud models. The results here presented can
help guide decisions on whether to include a time-dependent ice nucleation
scheme or a simpler singular description in models. |
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