Proceedings Article | 4 November 2003
KEYWORDS: Radiometry, Solar radiation, Ozone, Calibration, Satellites, Internet, Ultraviolet radiation, Analytical research, Spectral calibration, Lamps
Seasonal variation of global solar radiation: ultraviolet-B (UV-B: 290 - 320 nm), ultraviolet-A (UV-A: 320 - 400 nm) and Total (Total: 300 - 3000 nm) has been measured at the Shonan Campus of Tokai University (35°21’N, 139°16’E, in central Japan) since October 1990. To clarify regional difference of solar radiation in East Asia, the same type of radiometers were installed at Wakkanai (October 2000: 141°48’N, 145°21’E, in Hokkaido, at the northern end of Japan), Mashiki (June 1996: 32°50'N, 130°52'E, in Kumamoto, at the mid-west Japan) and Taketomi (July 1998: 24°20’N, 123°41'E, on Iriomote Island, in Okinawa, at the south western end of Japan). Observation data are transferred to the Shonan Campus every day via Internet, and the data were posted on our web site. Comparison of sensitivity among all radiometers used in this network was carried out from August 2002 to September 2002. Observed data were corrected based on the comparison results.
Solar radiation showed clear regional differences depending on the season. Global solar radiation in summer was almost the same among stations, but in winter, global radiation showed very significantly among the stations. The ratio of UV-B in winter to summer was 14 times at Wakkanai, 6 times at Shonan and Mashiki, and 2 times at Taketomi. The ratio of Total in winter to summer was 2 times at Shonan, Mashiki and Taketomi, and 6 times at Wakkanai. The seasonal variation of the ozone level corresponded the latitude with Taketomi registering the least amplitude.
