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LATITUDINAL AND SEASONAL VARIATION IN CALCULATED ULTRAVIOLET-B IRRADIANCE IN THE RICE-GROWING REGIONS OF ASIA
Citation:
Bachelet, D., P. Barnes, D. Brown, AND M. Brown. LATITUDINAL AND SEASONAL VARIATION IN CALCULATED ULTRAVIOLET-B IRRADIANCE IN THE RICE-GROWING REGIONS OF ASIA. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-91/193 (NTIS PB91240499), 1991.
Description:
Ultraviolet-B (UV-B, 280-329 nm) irradiance was calculated for more than 1200 sites in Asia to characterize the spatial and temporal variation in the present UV-B climate for rice-growing regions. he analytical model of Green et al. was used to compute UV-B irradiance for clear skies using satellite-observed ozone column thickness and local elevation data. round-based observations of cloud cover were then used to approximate the average effect of cloud cover on UV-B irradiance using the approach of Johnson et al. Over the geographic range of rice cultivation, the maximum daily effective UV-B irradiance (UV-B BE) when weighted according to a general plant action spectrum, was found to vary approximately 2.5-fold under both clear and cloudy sky conditions. nder clear skies, the timing of maximum solar UV-B BE changed with latitude and varied from February-March near the equator to July-August at temperate locations. loud cover was found to alter the season of maximum UV many tropical regions, due to the pronounced monsoonal climate, but had little effect on UV-B seasonality at higher latitudes. nder a climate resulting from a doubling of atmospheric carbon dioxide, estimated UV-B using predicted cloud cover was found to change by up to 17% from present conditions in Thailand. oth latitudinal and seasonal variation in solar UV-B radiation may be important aspects of the UV-B climate for rice as cultivars differ in sensitivity to UV-B and are grown under diverse conditions and locations.
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LATITUDINAL AND SEASONAL VARIATION IN CALCULATED ULTRAVIOLET-B IRRADIANCE IN THE RICE-GROWING REGIONS OF ASIA