EarthRef.org Reference Database (ERR)
Development and Maintenance by the EarthRef.org Database Team

Detailed Reference Information
Schafer et al. 1996
Schafer, J.S., Saxena, V.K., Wenny, B.N., Barnard, W. and De Luisi, J.J. (1996). Observed influence of clouds on ultraviolet-B radiation. Geophysical Research Letters 23: doi: 10.1029/96GL01984. issn: 0094-8276.

A Brewer Spectrophotometer was utilized to make ground-based measurements of solar ultraviolet (UV-B) radiation received at Black Mountain, NC (35.66 ¿N) in order to quantify the reduction of UV-B due to cloud cover. Observations were made over the interval February-July 1995 with continuous coverage except for a three-week period in May. A wide-angle lens video camera at the site was used for the assessment of cloud conditions at the time of each scan. Integrated UV-B (290--320 nm) values were evaluated and a regression through the values for clear conditions was produced for the range of zenith angles from 25¿--70¿. This regression effectively represents an average effect of the ambient aerosols and attenuating gases and was used to normalize the UV-B values measured under different cloud cover amounts, providing an estimate of the reduction in irradiance due to a given cloud amount as a function of solar zenith angle. For a solar zenith angle of 50¿, average UV-B transmission was observed to be 30% for overcast skies, 61% for 8--9 tenths cloud cover, 74% for 6--7 tenths cover, and 79% for the scans during 4--5 tenths cover. A number of fractional cloud cover cases were observed where cloud reflections resulted in measured surface irradiances exceeding the expected clear sky values by as much as 11 percent. ¿ American Geophysical Union 1996

BACKGROUND DATA FILES

Abstract

Keywords
Atmospheric Composition and Structure, Transmission and scattering of radiation
Journal
Geophysical Research Letters
http://www.agu.org/journals/gl/
Publisher
American Geophysical Union
2000 Florida Avenue N.W.
Washington, D.C. 20009-1277
USA
1-202-462-6900
1-202-328-0566
service@agu.org
Click to clear formClick to return to previous pageClick to submit