CCN Properties of Organic Aerosol Collected Below and within Marine Stratocumulus Clouds near Monterey, California
by
Akua Asa-Awuku 1,2,*, Armin Sorooshian 3
, Richard C. Flagan 4, John H. Seinfeld 5 and Athanasios Nenes 5,6,7
Akua Asa-Awuku 1,2,*, Armin Sorooshian 3, Richard C. Flagan 4, John H. Seinfeld 5 and Athanasios Nenes 5,6,7
1
Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA 92521, USA
2
Bourns College of Engineering, Center for Environmental Research and Technology, University of California, Riverside, Riverside, CA 92507, USA
3
Departments of Chemical and Environmental Engineering, and Atmospheric Sciences University of Arizona, Tucson, AZ 85721, USA
4
Department of Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
5
Schools of Chemical and Biomolecular Engineering and Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
6
Institute of Chemical Engineering Sciences, FORTH, Patras, GR-26504, Greece
7
Institute of Environmental Research and Sustainable Development, National Observatory of Athens, Palea Penteli, GR-15236, Greece
*
Author to whom correspondence should be addressed.
Academic Editor: Robert W. Talbot
Atmosphere 2015, 6(11), 1590-1607; https://doi.org/10.3390/atmos6111590
Received: 31 August 2015 / Revised: 5 October 2015 / Accepted: 10 October 2015 / Published: 28 October 2015
(This article belongs to the Special Issue Atmospheric Composition Observations)
The composition of aerosol from cloud droplets differs from that below cloud. Its implications for the Cloud Condensation Nuclei (CCN) activity are the focus of this study. Water-soluble organic matter from below cloud, and cloud droplet residuals off the coast of Monterey, California were collected; offline chemical composition, CCN activity and surface tension measurements coupled with Köhler Theory Analysis are used to infer the molar volume and surfactant characteristics of organics in both samples. Based on the surface tension depression of the samples, it is unlikely that the aerosol contains strong surfactants. The activation kinetics for all samples examined are consistent with rapid (NH4)2SO4 calibration aerosol. This is consistent with our current understanding of droplet kinetics for ambient CCN. However, the carbonaceous material in cloud drop residuals is far more hygroscopic than in sub-cloud aerosol, suggestive of the impact of cloud chemistry on the hygroscopic properties of organic matter.
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MDPI and ACS Style
Asa-Awuku, A.; Sorooshian, A.; Flagan, R.C.; Seinfeld, J.H.; Nenes, A. CCN Properties of Organic Aerosol Collected Below and within Marine Stratocumulus Clouds near Monterey, California. Atmosphere 2015, 6, 1590-1607.
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