Laboratory studies of collection efficiency of sub-micrometer aerosol particles by cloud droplets on a single-droplet basis
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Cziczo_laboratory studies.pdf
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Author(s)
Ardon Dryer, Karin
Cziczo, Daniel James
Huang, Y.-W.
Date Issued
August 2015
Journal
Atmospheric Chemistry and Physics
Publisher
Copernicus GmbH
Citation
Ardon-Dryer, K., Y.-W. Huang, and D. J. Cziczo. “Laboratory Studies of Collection Efficiency of Sub-Micrometer Aerosol Particles by Cloud Droplets on a Single-Droplet Basis.” Atmos. Chem. Phys. 15, no. 16 (2015): 9159–9171.
Version
Final published version
Abstract
An experimental setup has been constructed to measure the collection efficiency (CE) of sub-micrometer aerosol particles by cloud droplets. Droplets of a dilute aqueous ammonium sulfate solution with an average radius of 21.6 μm fall freely into a chamber and collide with sub-micrometer polystyrene latex (PSL) sphere particles of known sizes and concentrations. Two relative humidity (RH) conditions, 15 ± 3 % and 88 ± 3 %, hereafter termed "low" and "high", respectively, were varied with different particles sizes and concentrations. After passing through the chamber, the droplets and aerosol particles were sent to the Particle Analysis by Laser Mass Spectrometry (PALMS) instrument to determine chemical compositions on a single-droplet basis. "Coagulated droplets" (droplets that collected aerosols) had mass spectra that contained signatures from both an aerosol particle and a droplet residual. CE values range from 2.0 × 10[superscript −1] to 1.6 for the low-RH case and from 1.5 × 10[superscript −2] to 9.0 × 10[superscript −2] for the high-RH case. CE values were, within experimental uncertainty, independent of the aerosol concentrations. CE values in this study were found to be in agreement with previous experimental and theoretical studies. To our knowledge, this is the first collection experiment performed on a single-droplet basis with atmospherically relevant conditions such as droplet sizes, droplet charges and flow.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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DOI of Published Version
https://doi.org/10.5194/acp-15-9159-2015
