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GEOPHYSICAL RESEARCH LETTERS,
VOL. 35,
L03818,
doi:10.1029/2007GL031075,
2008
Cloud forming potential of secondary organic aerosol under near atmospheric conditions
J. Duplissy
Laboratory of Atmospheric Chemistry, Paul Scherrer Institut, Villigen, Switzerland
M. Gysel
Laboratory of Atmospheric Chemistry, Paul Scherrer Institut, Villigen, Switzerland
M. R. Alfarra
Laboratory of Atmospheric Chemistry, Paul Scherrer Institut, Villigen, Switzerland
J. Dommen
Laboratory of Atmospheric Chemistry, Paul Scherrer Institut, Villigen, Switzerland
A. Metzger
Laboratory of Atmospheric Chemistry, Paul Scherrer Institut, Villigen, Switzerland
A. S. H. Prevot
Laboratory of Atmospheric Chemistry, Paul Scherrer Institut, Villigen, Switzerland
E. Weingartner
Laboratory of Atmospheric Chemistry, Paul Scherrer Institut, Villigen, Switzerland
A. Laaksonen
Department of Physics, University of Kuopio, Kuopio, Finland
T. Raatikainen
Finnish Meteorological Institute, Helsinki, Finland
N. Good
Centre for Atmospheric Sciences, University of Manchester, Manchester, UK
S. F. Turner
Centre for Atmospheric Sciences, University of Manchester, Manchester, UK
G. McFiggans
Centre for Atmospheric Sciences, University of Manchester, Manchester, UK
U. Baltensperger
Laboratory of Atmospheric Chemistry, Paul Scherrer Institut, Villigen, Switzerland
Abstract
Cloud droplets form by nucleation on atmospheric aerosol particles. Populations of such particles invariably contain organic
material, a major source of which is thought to be condensation of photo-oxidation products of biogenic volatile organic compounds
(VOCs). We demonstrate that smog chamber studies of the formation of such biogenic secondary organic aerosol (SOA) formed
during photo-oxidation must be conducted at near atmospheric concentrations to yield atmospherically representative particle
composition, hygroscopicity and cloud-forming potential. Under these conditions, the hygroscopicity measured at 95% relative
humidity can be used reliably to predict the CCN activity of the SOA particles by assuming droplet surface tension of pure
water. We also show that the supersaturation required to activate a given size of particle decreases with age.
Received 21
June
2007;
accepted 5
December
2007;
published 15
February
2008.
Keywords: hygroscopicity;
secondary organic aerosol;
cloud condensation nuclei.
Index Terms: 3311 Atmospheric Processes: Clouds and aerosols; 0320 Atmospheric Composition and Structure: Cloud physics and chemistry; 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801, 4906).
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Citation: Duplissy, J., et al.
(2008),
Cloud forming potential of secondary organic aerosol under near atmospheric conditions,
Geophys. Res. Lett.,
35,
L03818,
doi:10.1029/2007GL031075.
Copyright 2008 by the American Geophysical Union.
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