Comparison of methods for deriving aerosol asymmetry parameter
Author
Andrews, E.
Sheridan, P. J.
Fiebig, M.
McComiskey, A.
Ogren, J. A.
Arnott, P.
Covert, D.
Elleman, R.
Gasparini, R.
Collins, D.
Jonsson, H.
Schmid, B.
Wang, J.
Date
2006Metadata
Show full item recordAbstract
Values for Mie-equivalent aerosol asymmetry parameter (g) were derived using a
variety of methods from the large suite of measurements (in situ and remote from surface
and aircraft) made in Oklahoma during the 2003 aerosol Intensive Operations Period
(IOP). Median values derived for dry asymmetry parameter at 550 nm ranged between
0.55 and 0.63 over all instruments and for all derivation methods, with the exception of
one instrument which did not measure over the full size range of optically important
aerosol. Median values for the ‘‘wet’’ asymmetry parameter (i.e., asymmetry parameter at
humidity conditions closer to ambient) were between 0.59 and 0.72. Values for g derived
for surface and airborne in situ measurements were highly correlated, but in situ and
remote sensing measurements both at the surface and aloft did not agree as well because of
vertical inhomogeneity of the aerosol. Radiative forcing calculations suggest that a
10% decrease in g would result in a 19% reduction in top of atmosphere radiative forcing
for the conditions observed during the IOP. Comparison of the different methods for
deriving g suggests that in computing the asymmetry parameter, aerosol size is the most
important parameter to measure; composition is less important except for how it influences
the hygroscopic growth (i.e., size) of particles.
Description
Journal of Geophysical Research, Vol. 111, No. D5, D05S04
The article of record as published may be located at http://dx.doi.org/10.1029/2004JD005734
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.Collections
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