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| Titel |
BINARY: an optical freezing array for assessing temperature and time dependence of heterogeneous ice nucleation |
| VerfasserIn |
C. Budke, T. Koop |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 8, no. 2 ; Nr. 8, no. 2 (2015-02-10), S.689-703 |
| Datensatznummer |
250116128
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| Publikation (Nr.) |
 copernicus.org/amt-8-689-2015.pdf |
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| Zusammenfassung |
| A new optical freezing array for the study of heterogeneous ice
nucleation in microliter-sized droplets is introduced, tested and
applied to the study of immersion freezing in aqueous
Snomax® suspensions. In the Bielefeld Ice
Nucleation ARraY (BINARY) ice nucleation can be studied
simultaneously in 36 droplets at temperatures down to
−40 °C (233 K) and at cooling rates between
0.1 and 10 K min−1. The droplets are
separated from each other in individual compartments, thus
preventing a Wegener–Bergeron–Findeisen type water vapor transfer
between droplets as well as avoiding the seeding of neighboring
droplets by formation and surface growth of frost halos. Analysis of
freezing and melting occurs via an automated real-time image analysis
of the optical brightness of each individual droplet. As an
application ice nucleation in water droplets containing
Snomax® at concentrations from
1 ng mL−1 to 1 mg mL−1 was
investigated. Using different cooling rates, a small time dependence
of ice nucleation induced by two different classes of ice nucleators (INs)
contained in Snomax® was detected and the corresponding
heterogeneous ice nucleation rate coefficient was quantified. The observed time
dependence is smaller than those of other types of INs reported in the literature,
suggesting that the BINARY setup is suitable for quantifying time
dependence for most other INs of atmospheric interest, making it
a useful tool for future investigations. |
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