Variation characteristics of Ultraviolet radiation derived from measurement and reconstruction in Beijing, China
会议名称：《第七届全国优秀青年气象科技工作者学术研讨会》
会议日期：2010年
学科分类：07[理学] 070601[理学-气象学] 0706[理学-大气科学]
基 金：supported financially by the National Basic Research Program (Grant Nos.: 2006CB403702) the Knowledge Innovation Key Projects of the Chinese Academy of Sciences (kzcx2-yw-433-04), and the Research Program for excellent Ph.D. dissertations in Chinese Academy of Science
关 键 词：Ultraviolet radiation solar radiation clearness index reconstruction long-term
摘 要：Measurements of RS and total Ultraviolet radiation （the sum of UV-A and UV-B） from 2005 to 2008 in Beijing were used to determine temporal variability of UV/RS and its dependence on water vapor content and clearness index. Results revealed that annual mean UV was 0.37 ± 0.17 MJ m-2 d-1. The highest daily value was measured in May, while the lowest value occurred in December. The monthly mean value of UV/Rs gradually increased from 2.7% in November to 3.7% in August, with annual mean 3.1%. A simple, efficient, and empirically derived all-weather model is proposed to estimate UV from RS. The annual mean daily UV radiation during 1958-2005 was 0.46 MJ m-2 d-1. UV radiation decreased from the early 1960s to the late 1990s but began to increase in the late 1990s. Over the latter half of the 20th century, decrease in UV radiation was 0.018 MJ m-2 d-1 per decade. The decrease trends in long-term annual mean UV radiation of -0.026 MJ m-2 d-1 per year for 1958-1997 and -0.0024 MJ m-2 d-1 per year for 1958-2005. The decreasing trend in UV radiation was sharpest in spring and summer but more gradual in autumn and winter.