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| Titel |
Chemical composition and mixing-state of ice residuals sampled within mixed phase clouds |
| VerfasserIn |
M. Ebert, A. Worringen, N. Benker, S. Mertes, E. Weingärtner, S. Weinbruch |
| 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 ; 11, no. 6 ; Nr. 11, no. 6 (2011-03-25), S.2805-2816 |
| Datensatznummer |
250009522
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| Publikation (Nr.) |
 copernicus.org/acp-11-2805-2011.pdf |
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| Zusammenfassung |
| During an intensive campaign at the high alpine research station
Jungfraujoch, Switzerland, in February/March 2006 ice particle residuals
within mixed-phase clouds were sampled using the Ice-counterflow virtual
impactor (Ice-CVI). Size, morphology, chemical composition, mineralogy and
mixing state of the ice residual and the interstitial (i.e., non-activated)
aerosol particles were analyzed by scanning and transmission electron
microscopy. Ice nuclei (IN) were identified from the significant enrichment
of particle groups in the ice residual (IR) samples relative to the
interstitial aerosol. In terms of number lead-bearing particles are enriched
by a factor of approximately 25, complex internal mixtures with silicates or
metal oxides as major components by a factor of 11, and mixtures of
secondary aerosol and carbonaceous material (C-O-S particles) by a factor of
2. Other particle groups (sulfates, sea salt, Ca-rich particles, external
silicates) observed in the ice-residual samples cannot be assigned
unambiguously as IN. Between 9 and 24% of all IR are Pb-bearing
particles. Pb was found as major component in around 10% of these
particles (PbO, PbCl2). In the other particles, Pb was found as some
100 nm sized agglomerates consisting of 3–8 nm sized primary particles
(PbS, elemental Pb). C-O-S particles are present in the IR at an abundance
of 17–27%. The soot component within these particles is strongly
aged. Complex internal mixtures occur in the IR at an abundance of 9–15%.
Most IN identified at the Jungfraujoch station are internal mixtures
containing anthropogenic components (either as main or minor constituent),
and it is concluded that admixture of the anthropogenic component is
responsible for the increased IN efficiency within mixed phase clouds. The
mixing state appears to be a key parameter for the ice nucleation behaviour
that cannot be predicted from the sole knowledge of the main component of an
individual particle. |
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