Intercomparing different devices for the investigation of ice nucleating particles using Snomax® as test substance

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 P
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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Author:Heike Wex, Stefanie Augustin-Bauditz, Yvonne Boose, Carsten Budke, Joachim Curtius, Karoline Diehl, Axel Dreyer, Fabian Frank, Susan Hartmann, Naruki Hiranuma, Evelyn Jantsch, Zamin A. Kanji, Alexei Kiselev, Thomas Koop, Ottmar Möhler, Dennis Niedermeier, Björn Nillius, Michael Rösch, Diana Rose, C. Schmidt, Isabelle Steinke, Frank Stratmann
URN:urn:nbn:de:hebis:30:3-372520
DOI:http://dx.doi.org/10.5194/acp-15-1463-2015
ISSN:1680-7324
Parent Title (English):Atmospheric chemistry and physics
Publisher:European Geosciences Union
Place of publication:Katlenburg-Lindau
Document Type:Article
Language:English
Date of Publication (online):2015/02/10
Date of first Publication:2015/02/10
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2015/04/22
Volume:15
Pagenumber:23
First Page:1463
Last Page:1485
Note:
© Author(s) 2015. This work is distributed under the Creative Commons Attribution 3.0 License.
HeBIS PPN:369072006
Institutes:Geowissenschaften
Dewey Decimal Classification:550 Geowissenschaften
Sammlungen:Universitätspublikationen
Licence (German):License LogoCreative Commons - Namensnennung 3.0

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