Importance of aerosol composition, mixing state, and morphology for heterogeneous ice nucleation: A combined field and laboratory approach
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Author(s)
Baustian, Kelly J.
Cziczo, Daniel James
Wise, Matthew E.
Pratt, Kerri A.
Kulkarni, Gourihar
Hallar, A. Gannet
Tolbert, Margaret A.
Date Issued
March 2012
Journal
Journal of Geophysical Research Atmospheres
Publisher
American Geophysical Union (AGU)
Citation
Baustian, Kelly J. et al. “Importance of Aerosol Composition, Mixing State, and Morphology for Heterogeneous Ice Nucleation: A Combined Field and Laboratory Approach.” Journal of Geophysical Research 117.D6 (2012). ©2012. American Geophysical Union.
Version
Final published version
Abstract
In this study chemical compositions of background aerosol and ice nuclei were examined through laboratory investigations using Raman spectroscopy and field measurements by single-particle mass spectrometry. Aerosol sampling took place at Storm Peak Laboratory in Steamboat Springs, Colorado (elevation of 3210 m). A cascade impactor was used to collect coarse-mode aerosol particles for laboratory analysis by Raman spectroscopy; the composition, mixing state, and heterogeneous ice nucleation activity of individual particles were examined. For in situ analysis of fine-mode aerosol, ice nucleation on ambient particles was observed using a compact ice nucleation chamber. Ice crystals were separated from unactivated aerosol using a pumped counterflow virtual impactor, and ice nuclei were analyzed using particle analysis by laser mass spectrometry. For both fine and coarse modes, the ice nucleating particle fractions were enriched in minerals and depleted in sulfates and nitrates, compared to the background aerosol sampled. The vast majority of particles in both the ambient and ice active aerosol fractions contained a detectable amount of organic material. Raman spectroscopy showed that organic material is sometimes present in the form of a coating on the surface of inorganic particles. We find that some organic-containing particles serve as efficient ice nuclei while others do not. For coarse-mode aerosol, organic particles were only observed to initiate ice formation when oxygen signatures were also present in their spectra.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1029/2011jd016784
