Influence of high levels of cloud cover on vitamin D effective and erythemal solar UV irradiances

Parisi, Alfio V. and Turnbull, David J. and Downs, Nathan J. (2012) Influence of high levels of cloud cover on vitamin D effective and erythemal solar UV irradiances. Photochemical and Photobiological Sciences, 11 (12). pp. 1855-1859. ISSN 1474-905X

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Abstract

The solar irradiances for the initiation of vitamin D synthesis (UVD3) have been measured concurrently with the amount of cloud cover to investigate the influence of high cloud cover fraction. The cases of 6.5 and more octa cloud cover were considered for five solar zenith angle (SZA) ranges up to 80o. For each of the SZA ranges, the UVD3 reduced due to the high cloud cover. The average of the ratios of the UVD3 irradiances on a cloudy day to those on a clear day with the corresponding ozone and SZA are 0.71 for the 6.5-7.5 octa cloud and 0.45 for the more than 7.5 octa cloud ranges. The exposure times necessary to receive 1/3 MED to a horizontal plane were found to increase as the amount of cloud cover increased. For each cloud cover category, the range of values increased with cloud cover and with SZA. This research shows that the current public recommendations on the times of solar UV exposures required to produce adequate vitamin D are inappropriate for situations of more than 6.5 octa cloud.

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Item Type:	Article (Commonwealth Reporting Category C)
Refereed:	Yes
Item Status:	Live Archive
Additional Information:	Accepted version deposited in accordance with the copyright policy of the publisher. Permanent restricted access to published version due to publisher copyright policy.
Faculty/School / Institute/Centre:	Historic - Faculty of Sciences - Department of Biological and Physical Sciences
Date Deposited:	12 Mar 2013 21:39
Last Modified:	18 Aug 2014 23:28
Uncontrolled Keywords:	cloud; vitamin D; UV; octa
Fields of Research :	02 Physical Sciences > 0299 Other Physical Sciences > 029999 Physical Sciences not elsewhere classified
Socio-Economic Objective:	E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Identification Number or DOI:	10.1039/c2pp25160d
URI:	http://eprints.usq.edu.au/id/eprint/22289

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