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Titel |
Improved sky imaging for studies of enhanced UV irradiance |
VerfasserIn |
J. M. Sabburg, C. N. Long |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1680-7316
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Digitales Dokument |
URL |
Erschienen |
In: Atmospheric Chemistry and Physics ; 4, no. 11/12 ; Nr. 4, no. 11/12 (2004-12-14), S.2543-2552 |
Datensatznummer |
250001429
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Publikation (Nr.) |
copernicus.org/acp-4-2543-2004.pdf |
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Zusammenfassung |
A recent World Meteorological Organisation report discussed the importance of
continued study of the effect of clouds on the solar UV radiation reaching the earth's
surface. The report mentions that the use of all-sky imagery offers the potential to
understand and quantify cloud effects more accurately. There are an increasing number of
studies investigating the enhancement of surface solar, UV irradiance, and UV actinic
flux, using automated CCD and sky imagers. This paper describes new algorithms
applicable to a commercially available all-sky imager (TSI-440), for research
investigating cloud enhanced spectral UV irradiance. Specifically, these include three
new algorithms relating to cloud amount at different spatial positions from 1) zenith and
2) from the solar position and 3) the visible brightness of clouds surrounding the sun. A
possible relationship between UV enhancement and the occurrence of near-sun cloud
brightness is reported based on this preliminary data. It is found that a range of
wavelength dependent intensities, from 306 to 400 nm, can occur in one day for UV
enhancements. Evidence for a possible decreasing variation of intensity with longer
wavelengths is also presented. |
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