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JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 108, NO. D23,
8660,
doi:10.1029/2002JD003233,
2003
Surface aerosol radiative forcing at Gosan during the ACE-Asia campaign
Brett C. Bush
Atmospheric Research Laboratory, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California,
USA
Francisco P. J. Valero
Atmospheric Research Laboratory, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California,
USA
Abstract
Surface radiation measurements were made at Gosan, Jeju, Republic of Korea, during the ACE-Asia field campaign aimed at assessing
the impact of aerosols, specifically the “Asian yellow dust,” throughout the region. Downwelling total, direct, and diffuse
radiative fluxes were measured in the total solar spectrum as well as near-infrared and visible portions of the spectrum.
Aerosol optical depth measurements at 500 nm were also made using a scanning shadow band radiometer. Surface radiative forcing
values were determined during clear-sky conditions made from 25 March to 4 May 2001. The diurnal forcing efficiency, determined
by taking the slope of the best fit line through the flux versus optical depth plot, was found to be −73.0 ± 9.6, −35.8 ±
5.5, and − 42.2 ± 4.8 W m−2/τ500 for the total solar, near-infrared, and visible spectral regions. We also introduce a new radiative forcing parameter, the
fractional forcing efficiency, defined to express the radiative forcing relative to the total energy incident at the top of
the atmosphere. The fractional diurnal forcing efficiency at Gosan during ACE-Asia was −18.0 ± 2.3, −16.2 ± 2.4, and −26.7
± 3.3%/τ500 for the same band passes, indicating that a larger percentage of the flux at visible wavelengths is radiatively forced compared
to the total and near-infrared portions of the solar spectrum.
Received 27
November
2002;
accepted 27
March
2003;
published 26
August
2003.
Index Terms: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801); 0360 Atmospheric Composition and Structure: Transmission and scattering of radiation; 0394 Atmospheric Composition and Structure: Instruments and techniques.
Read Full Article (file size: 681349 bytes) Cited by
Citation: Bush, B. C., and F. P. J. Valero
(2003),
Surface aerosol radiative forcing at Gosan during the ACE-Asia campaign,
J. Geophys. Res.,
108(D23),
8660,
doi:10.1029/2002JD003233.
Copyright 2003 by the American Geophysical Union.
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