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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/acp-2018-81
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
05 Mar 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Atmospheric Chemistry and Physics (ACP).
Ice-nucleating efficiency of aerosol particles and possible sources at three coastal marine sites
Meng Si1, Victoria E. Irish1, Ryan H. Mason1, Jesús Vergara-Temprado2, Sarah Hanna1, Luis A. Ladino3,a, Jacqueline D. Yakobi-Hancock3, Corinne L. Schiller4, Jeremy J. B. Wentzell5, Jonathan P. D. Abbatt3, Ken S. Carslaw2, Benjamin J. Murray2, and Allan K. Bertram1 1Department of Chemistry, University of British Columbia, Vancouver, V6T1Z1, Canada
2Institute for Climate and Atmospheric Science, School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK
3Department of Chemistry, University of Toronto, Toronto, M5S3H6, Canada
4Air Quality Science Unit, Environment and Climate Change Canada, Vancouver, V6C3S5, Canada
5Air Quality Research Division, Environment and Climate Change Canada, Toronto, M3H5T4, Canada
anow at: Centro de Ciencias de la Atmósfera, Universidad Nacional Autónoma de México, Ciudad Universitaria, Mexico City, Mexico
Abstract. Despite the importance of ice-nucleating particles (INPs) for climate and precipitation, our understanding of these particles is far from complete. Here, we investigated INPs at three coastal marine sites in Canada, two at mid-latitude (Amphitrite Point and Labrador Sea), and one in the Arctic (Lancaster Sound). At all three sites, the ice-nucleating efficiency on a per number basis (expressed as the fraction of aerosol particles acting as an INP) was strongly dependent on the size. For example, at diameters of around 0.2 µm, approximately 1 in 106 particles acted as an INP at −25 ºC, while at diameters of around 8 µm, approximately 1 in 10 particles acted as an INP at −25 ºC. The ice-nucleating efficiency on a per surface area basis (expressed as the surface active site density, ns) was also dependent on the size, with larger particles being more efficient at nucleating ice. The ns values of supermicron particles at Amphitrite Point and Labrador Sea were larger than previously measured ns values of sea spray aerosol, suggesting that sea spray aerosol was not a major contributor to the supermicron INP population at these two sites. Consistent with this observation, a global model of INP concentrations under-predicted the INP concentrations when assuming only marine organics as INPs. On the other hand, assuming only K-feldspar as INPs, the same model was able to reproduce the measurements at a freezing temperature of −25 ºC, but under-predicted INP concentrations at −15 ºC, suggesting that the model is missing a source of INPs active at a freezing temperature of −15 ºC.
Citation: Si, M., Irish, V. E., Mason, R. H., Vergara-Temprado, J., Hanna, S., Ladino, L. A., Yakobi-Hancock, J. D., Schiller, C. L., Wentzell, J. J. B., Abbatt, J. P. D., Carslaw, K. S., Murray, B. J., and Bertram, A. K.: Ice-nucleating efficiency of aerosol particles and possible sources at three coastal marine sites, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2018-81, in review, 2018.
Meng Si et al.
Meng Si et al.

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Short summary
Using the concentrations of ice-nucleating particles (INPs) and total aerosol particles measured at three coastal marine sites, the ice-nucleating efficiency of aerosol particles as a function of size was determined. The ice-nucleating efficiency was strongly dependent on size, with larger particles being more efficient. This type of information can help determine or rule out the sources of INPs, and constrain future modeling of INPs and mixed-phase clouds.
Using the concentrations of ice-nucleating particles (INPs) and total aerosol particles measured...
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