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4 November 2003 Defining the probabilities of solar UV event exposures for plant effects research
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Studies into the biological effects of acute exposures requires understanding of the probability of an event of a given intensity and duration. The occurrence of high hourly biologically-effective UVB (UVBBE) exposures were evaluated for the 1997-2001 summer growing seasons (May-August) at five locations between 38° and 41° longitude across the continental United States. In general, the frequency of extreme hourly exposures decreased from west to east. The daily UVBBE exposures resulting from the extreme hourly UVBBE exposures were inversely correlated with TOC for that day. Hourly exposures in the upper 10% of all exposures occurred most frequently during June and July. There was a 30% probability of having a day with 2h of exposure in the upper 5% of UVBBE values across the entire USA. The probability of having two sequential days with 2h of high exposure was approximately 10% most locations. The probability of having six sequential days of 2h extreme exposure was approximately equivalent to two to three days of 4h extreme exposure. Based on this analysis, a reasonable exposure regime for acute UVB effects on plants is the insertion of a 1 kJm-2 h-1 UVBBE exposure for two to four hours into the ambient conditions for three sequential days.
© (2003) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Richard H. Grant and James R. Slusser "Defining the probabilities of solar UV event exposures for plant effects research", Proc. SPIE 5156, Ultraviolet Ground- and Space-based Measurements, Models, and Effects III, (4 November 2003);

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