1994 Arctic Ocean Section
Aerosols
John D. Grovenstein, Richard Leaitch and Fred Hopper
Aerosols, especially those that influence cloud microphysics (droplet size
spectra), are important in atmospheric research because they influence climate
directly by backscattering and absorption of incoming solar radiation and in-
directly by affecting cloud albedo. Wigley (1989) suggested that the latter
effect could be the reason that the planet has not exhibited heating as predict-
ed by global climate models of the
"greenhouse effect." Generally
10000
climate models are poorly param-
CN
CCN (1% S)
eterized for aerosol and cloud mi-
PCN (0.33% S)
crophysics, especially in the remote
1000
CASP
Arctic. Therefore, it is necessary to
measure these parameters to pro-
vide data sets for modelers and to
100
diagnose future environmental
change.
The figure at the left is a time
10
series of aerosol concentration
from AOS-94. The uppermost
dotted line is the condensation
1
nuclei (CN) concentration mea-
208
212
216
220
224
228
232
236
240
Day (1994)
sured by TSI models 3025 and
3022 condensation nuclei counters. This number represents the concentra-
Time series of
aerosol concentra-
tion of the finest nuclei (nucleation mode) with a radius of 0.003 m to the
tion for the AOS-94
larger aerosols up to a radius of 3 m. The uppermost solid line is the cloud
expedition.
condensation nuclei (CCN) concentration active at 1% supersaturation. These
measurements were taken with an instantaneous CCN spectrometer intro-
duced by Fukuta and Saxena (1979). For this study the spectrometer was op-
erated at a range of 0.21.3% supersaturation. The spectrometer makes one
spectral sweep every 15 s. The middle dotted line is the CCN concentration
active at 0.33% supersaturation measured by the DH Associates cloud con-
John Grovenstein is with the Department of Marine, Earth and Atmospheric Sciences at North Carolina State
University in Raleigh, North Carolina, U.S.A. Richard Leaitch and Fred Hopper are with the Atmospheric
Environment Service, Downsview, Ontario, Canada.
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