Articles | Volume 17, issue 1
https://doi.org/10.5194/acp-17-575-2017
https://doi.org/10.5194/acp-17-575-2017
Research article
 | 
12 Jan 2017
Research article |  | 12 Jan 2017

Online single particle analysis of ice particle residuals from mountain-top mixed-phase clouds using laboratory derived particle type assignment

Susan Schmidt, Johannes Schneider, Thomas Klimach, Stephan Mertes, Ludwig Paul Schenk, Piotr Kupiszewski, Joachim Curtius, and Stephan Borrmann

Abstract. In situ single particle analysis of ice particle residuals (IPRs) and out-of-cloud aerosol particles was conducted by means of laser ablation mass spectrometry during the intensive INUIT-JFJ/CLACE campaign at the high alpine research station Jungfraujoch (3580 m a.s.l.) in January–February 2013. During the 4-week campaign more than 70 000 out-of-cloud aerosol particles and 595 IPRs were analyzed covering a particle size diameter range from 100 nm to 3 µm. The IPRs were sampled during 273 h while the station was covered by mixed-phase clouds at ambient temperatures between −27 and −6 °C. The identification of particle types is based on laboratory studies of different types of biological, mineral and anthropogenic aerosol particles. The outcome of these laboratory studies was characteristic marker peaks for each investigated particle type. These marker peaks were applied to the field data. In the sampled IPRs we identified a larger number fraction of primary aerosol particles, like soil dust (13 ± 5 %) and minerals (11 ± 5 %), in comparison to out-of-cloud aerosol particles (2.4 ± 0.4 and 0.4 ± 0.1 %, respectively). Additionally, anthropogenic aerosol particles, such as particles from industrial emissions and lead-containing particles, were found to be more abundant in the IPRs than in the out-of-cloud aerosol. In the out-of-cloud aerosol we identified a large fraction of aged particles (31 ± 5 %), including organic material and secondary inorganics, whereas this particle type was much less abundant (2.7 ± 1.3 %) in the IPRs. In a selected subset of the data where a direct comparison between out-of-cloud aerosol particles and IPRs in air masses with similar origin was possible, a pronounced enhancement of biological particles was found in the IPRs.

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Short summary
Ice formation in clouds is an important process in the formation of precipitation, especially at midlatitudes, but the exact properties of the aerosol particles that initiate freezing is not fully understood. We analysed residual particles from ice crystals sampled from mixed phase clouds. The results show that the residues contain a larger relative amount of soil dust and minerals, but also particles from industrial emissions and lead-containing particles, than the out-of-cloud aerosol.
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