北京市紫外线指数的观测研究

Experimental Study on the Ultraviolet Index in Beijing

1999年5月—2001年10月在北京观象台对紫外线指数(UVI)进行了长期观测,结果表明:UVI季节差异明显,春、夏、秋、冬季的最大值分别为7 85,9 87,4 92,2 99;正午时的平均值分别为3 52,5 31,2 17,1 24。在UVI高峰时段(10:00—15:00),秋、冬季的UVI基本在0～2范围,对人体危害不大;而0～2,3～4,5～6,大于7的各级UVI的平均累积日照时间春季分别为159,87,47,2min,夏季分别为75,99,93,29min,春、夏季紫外线辐射对人体危害较大。另外,UVI的累积分布显示,春、秋、冬季的UVI多数集中在各季节平均值以下,而夏季正午前后的UVI多分布在其季节平均值以上。

Ultraviolet Index (UVI) was measured at Beijing Observatory between May 1999 and October 2001.The results show that the UVI varies significantly in different seasons.The maximum of UVI is 7\^85,987,492 and 299 in spring,summer,autumn and winter,and the seasonal averaged UVI at noon is 352,531,217 and 124 respectively.The UVI reaches its peak between 10:00 and 15:00 in every day.And during the period of time,the UVI is generally in the range of 0～2 in autumn and winter,which has less harm to human health.But in spring,the mean accumulative irradiation time is 159,87,47 and 2 minutes,and 75,99,93 and 29 minutes in summer for the UVI of 0～2,3～4,5～6 and above 7,respectively.So the ultraviolet radiation in spring and summer is very detrimental to human health.In addition,the accumulative distribution of UVI shows that the majority of UVI is below its mean value in spring,autumn and winter,but in summer,around noon most UVI is above its mean value.