Moderation of cloud reduction of UV in the Antarctic due to high surface albedo

To gauge the impact of clouds on erythemal (sunburn causing) UV irradiances under different surface albedo conditions, UV measurements from two Antarctic sites (McMurdo and South Pole Stations) and a midlatitude site (Lauder, New Zealand) are examined. The surface albedo at South Pole remains high t...

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Bibliographic Details
Published inJournal of applied meteorology and climatology Vol. 42; no. 8; p. 1174
Main Authors Nichol, S E, Pfister, G, Bodeker, G E, McKenzie, R L
Format Journal Article
LanguageEnglish
Published Boston American Meteorological Society 01.08.2003
Subjects
Albedo
Clouds
Latitude
Optical analysis
Ozone
Radiative transfer
Solar energy
Ultraviolet radiation
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Summary:To gauge the impact of clouds on erythemal (sunburn causing) UV irradiances under different surface albedo conditions, UV measurements from two Antarctic sites (McMurdo and South Pole Stations) and a midlatitude site (Lauder, New Zealand) are examined. The surface albedo at South Pole remains high throughout the year, at McMurdo it has a strong annual cycle, and at Lauder it is low throughout the year. The measurements at each site are divided into clear and cloudy subsets and are compared with modeled clear-sky irradiances to assess the attenuation of UV by clouds. A radiative transfer model is also used to interpret the observations. Results show increasing attenuation of UV with increasing cloud optical depth, but a high surface albedo can moderate this attenuation as a result of multiple scattering between the surface and cloud base. This effect is of particular importance at high latitudes where snow may be present during the summer months. There is also a tendency toward greater cloud attenuation with increasing solar zenith angle. [PUBLICATION ABSTRACT]
ISSN:1558-8424
1558-8432