拉萨地区生物有效紫外辐射初步分析

A Preliminary Study of the Biologically Effective Ultraviolet Radiation of the Lhasa Area

根据1996～1998年由NILUV紫外辐射仪在西藏拉萨地区观测的紫外辐射资料,分析了青藏高原拉萨地区生物有效辐射的分布特征.结果表明,1997年日正午最大生物有效紫外辐射剂量率(UV dose rate)达到500mW m-2,最小值为9.7 mW m-2;晴天时生物有效辐射剂量率的日变化呈规则曲线,且早晚小,中午大;一年中紫外辐射变化的总趋势是由太阳天顶角决定的,紫外辐射的日变化和年变化是其最主要、最基本的变化;西藏拉萨地区的月平均红斑辐射剂量明显高于全球其他同纬度地区.

The characteristics of biologically effective UV in Lhasa are analyzed in this paper on the basis of the measurements with multichannel moderate bandwith filter instruments from 1996 to 1998 in Lhasa. The results show that the max UV dose rate is 500.0 mW m-2 and the min UV dose rate is 9.7 mW m-2 at local noon of 1997. For clear sky, the variations of daily UV dose rate are regular curve and UV dose rate at noon is larger than that at morning and evening. The basic variations of UV dose rate in a year are mainly determined by solar zenith angle (SZA). On the other hand, a comparison between monthly mean daily erythemal UV dose of Lhasa and that of other locations demonstrates the extremely high UV radiation on the Tibetan Plateau. The values of Lhasa from May to August are higher than those of San Diego by a factor of 1.3 ~1.4 and in summer values of Lhasa are even higher by a factor of 1.2~1.4 than those of Perch which has a similar latitude to Lhasa.