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Proceedings Paper

Year-to-year variations of the vitamin D synthesis related UV-B radiation in Estonia in autumn and spring
Author(s): Kalju Eerme; Uno Veismann; Ilmar Ansko; Silver Lätt
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Paper Abstract

In the geographic latitudes above 50° there is a period in each winter when the level of short-wave ultraviolet radiation (UVR) remains below the threshold needed for vitamin D synthesis in human skin. Vitamin D is produced with maximum efficiency at wavelengths around 297 nm. We proceed from the assumption that spectral irradiance at 306 nm is closely related to that at the wavelength 297 nm. The daily totals of the continuously recorded 306 nm spectral irradiance above the threshold value for vitamin D production have been studied during spring and autumnal transition periods as well as in summer. The "vitamin D winter" at the Tartu-Toravere Meteorological Station site (58.16'N, 26°.28'E, 70 m a.s.l.) lasted for 100-105 days from about Nov 6 to Feb 19 in cloudless weather and climatic total ozone conditions. During the closest 10 days to the conventional "vitamin D winter" in the most unfavorable conditions there could be no availability of the vitamin D synthesizing irradiance above its threshold level. In the most favorable conditions in separate cases small doses above the threshold could be available even about two weeks before the conventional end of the "vitamin D winter".

Paper Details

Date Published: 12 October 2006
PDF: 7 pages
Proc. SPIE 6362, Remote Sensing of Clouds and the Atmosphere XI, 636216 (12 October 2006); doi: 10.1117/12.688976
Show Author Affiliations
Kalju Eerme, Tartu Observatory (Estonia)
Uno Veismann, Tartu Observatory (Estonia)
Ilmar Ansko, Tartu Observatory (Estonia)
Silver Lätt, Tartu Observatory (Estonia)


Published in SPIE Proceedings Vol. 6362:
Remote Sensing of Clouds and the Atmosphere XI
James R. Slusser; Klaus Schäfer; Adolfo Comerón, Editor(s)

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