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| Titel |
Intercomparing different devices for the investigation of ice nucleating particles using Snomax® as test substance |
| VerfasserIn |
H. Wex, S. Augustin-Bauditz, Y. Boose, C. Budke, J. Curtius, K. Diehl, A. Dreyer, F. Frank, S. Hartmann, N. Hiranuma, E. Jantsch, Z. A. Kanji, A. Kiselev, T. Koop, O. Möhler, D. Niedermeier, B. Nillius, M. Rösch, D. Rose, C Schmidt, I. Steinke, F. Stratmann |
| 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. 3 ; Nr. 15, no. 3 (2015-02-10), S.1463-1485 |
| Datensatznummer |
250119402
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| Publikation (Nr.) |
 copernicus.org/acp-15-1463-2015.pdf |
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| Zusammenfassung |
| Seven different instruments and measurement methods were used to examine the
immersion freezing of bacterial ice nuclei from
Snomax® (hereafter Snomax), a product
containing ice-active protein complexes from non-viable Pseudomonas
syringae bacteria. The experimental conditions were kept as similar as
possible for the different measurements. Of the participating instruments,
some examined droplets which had been made from suspensions directly, and the
others examined droplets activated on previously generated Snomax particles,
with particle diameters of mostly a few hundred nanometers and up to a few
micrometers in some cases. Data were obtained in the temperature range from
−2 to −38 °C, and it was found that all ice-active protein
complexes were already activated above −12 °C. Droplets with
different Snomax mass concentrations covering 10 orders of magnitude were
examined. Some instruments had very short ice nucleation times down to below
1 s, while others had comparably slow cooling rates around 1 K min−1.
Displaying data from the different instruments in terms of numbers of ice-active protein complexes per dry mass of Snomax, nm, showed
that within their uncertainty, the data agree well with each other as well as
to previously reported literature results. Two parameterizations were taken
from literature for a direct comparison to our results, and these were a time-dependent approach based on a contact angle distribution (Niedermeier
et al., 2014) and a modification of the parameterization presented in
Hartmann et al. (2013) representing a time-independent approach. The
agreement between these and the measured data were good; i.e., they agreed
within a temperature range of 0.6 K or equivalently a range in
nm of a factor of 2. From the results presented herein, we
propose that Snomax, at least when carefully shared and prepared, is a
suitable material to test and compare different instruments for their
accuracy of measuring immersion freezing. |
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