Hygroscopic growth of sub-micrometer and one-micrometer aerosol particles measured during ACE-Asia A. Massling1, S. Leinert2, A. Wiedensohler1, and D. Covert3 1Leibniz-Institute for Tropospheric Research, Permoserstr. 15, 04318 Leipzig, Germany 2Environmental Protection Agency, Richview, Clonskeagh Road, Dublin 14, Ireland 3Department of Atmospheric Sciences, University of Washington, Box 354235, Seattle, WA 98195-4235, USA
Abstract. Hygroscopic properties of aerosol particles in the sub-micrometer and
one-micrometer size ranges were measured during the ACE-Asia study (Aerosol
Characterization Experiment-Asia) in spring 2001. The measurements took
place off the coasts of Japan, Korea, and China. All instruments
contributing to this study were deployed in a container on the forward deck
of the NOAA Research Vessel Ronald H. Brown. Air masses with primarily
marine influence and air masses from the Asian continent affected by both
anthropogenic sources and by the transport of desert dust aerosol were
encountered during the cruise.
Results showed very different hygroscopic behavior in the sub-micrometer
size range compared to the one-micrometer size range. In general, for all
continentally influenced air masses, the one-micrometer particle population
was characterized by two different particle groups – a nearly hydrophobic
fraction with growth factors around 1.0 representative of dust particles and
a sea salt fraction with hygroscopic growth factors around 2.0. The number
fraction of dust particles was generally about 60% independent of
long-range air mass origin.
For sub-micrometer particles, a dominant, more hygroscopic particle fraction
with growth factors between 1.5 and 1.9 (depending on dry particle size)
consistent with ammonium sulfate or non-neutralized sulfates as major
component was always found. In marine air masses and for larger sizes within
the sub-micrometer range (Dp=250 and 350 nm), a sea salt fraction with growth
factors between 2.0 and 2.1 was also observed. For all other air masses, the
more hygroscopic particle fraction in the sub-micrometer size range was
mostly accompanied by a less hygroscopic particle fraction with growth
factors between 1.20 and 1.55 depending on both the continental sources and
the dry particle size. Number fractions of this particle group varied
between 4 and 39% depending on dry particle size and air mass type.
Nearly hydrophobic particles indicating dust particles in the sub-micrometer
size regime were only found for particles with Dp=250 and 350 nm during a
time period when the aerosol was influenced by transport from Asian desert
Citation: Massling, A., Leinert, S., Wiedensohler, A., and Covert, D.: Hygroscopic growth of sub-micrometer and one-micrometer aerosol particles measured during ACE-Asia, Atmos. Chem. Phys., 7, 3249-3259, doi:10.5194/acp-7-3249-2007, 2007.