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| Titel |
Laboratory measurements and model sensitivity studies of dust deposition ice nucleation |
| VerfasserIn |
G. Kulkarni, J. Fan, J. M. Comstock, X. Liu, M. Ovchinnikov |
| 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 ; 12, no. 16 ; Nr. 12, no. 16 (2012-08-16), S.7295-7308 |
| Datensatznummer |
250011384
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| Publikation (Nr.) |
 copernicus.org/acp-12-7295-2012.pdf |
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| Zusammenfassung |
| We investigated the ice nucleating properties of mineral dust particles to
understand the sensitivity of simulated cloud properties to two different
representations of contact angle in the Classical Nucleation Theory (CNT).
These contact angle representations are based on two sets of laboratory
deposition ice nucleation measurements: Arizona Test Dust (ATD) particles of
100, 300 and 500 nm sizes were tested at three different temperatures (−25,
−30 and −35 °C), and 400 nm ATD and kaolinite dust species were
tested at two different temperatures (−30 and −35 °C). These
measurements were used to derive the onset relative humidity with respect to
ice (RHice) required to activate 1% of dust particles as ice
nuclei, from which the onset single contact angles were then calculated based
on CNT. For the probability density function (PDF) representation, parameters
of the log-normal contact angle distribution were determined by fitting
CNT-predicted activated fraction to the measurements at different
RHice. Results show that onset single contact angles vary from
~18 to 24 degrees, while the PDF parameters are sensitive to the
measurement conditions (i.e. temperature and dust size). Cloud modeling
simulations were performed to understand the sensitivity of cloud properties
(i.e. ice number concentration, ice water content, and cloud initiation
times) to the representation of contact angle and PDF distribution
parameters. The model simulations show that cloud properties are sensitive to
onset single contact angles and PDF distribution parameters. The comparison
of our experimental results with other studies shows that under similar
measurement conditions the onset single contact angles are consistent within
±2.0 degrees, while our derived PDF parameters have larger discrepancies. |
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