三江平原紫外辐射变化特征

利用2005~2011年共7年的太阳辐射观测资料对三江平原紫外辐射的时间变化规律及紫外辐射与总辐射比值的变化特征进行了分析,结果表明紫外辐射与总辐射的变化规律一致,日变化为正午大、早晚小;季节变化规律是夏季高、冬季低。紫外辐射日累积值的7年年平均值为0.53 MJ m–2 d–1。紫外辐射与总辐射比值存在着明显日、季节变化特征,日变化特征为正午大、早晚小,而季节变化与紫外辐射的季节变化一致也是夏季大、冬季小。紫外辐射与总辐射比值7年平均为0.0433。利用2011年观测的总辐射、紫外辐射数据,通过紫外辐射与总辐射比值和大气质量数与晴空指数的相互依赖关系,建立了适合于三江地区紫外辐射估算的方程。利用建立的估算方程估算的紫外辐射瞬时值和日累积值与观测值之间的平均相对误差最大分别为8.5%和6.1%。

Variation Characteristics of Ultraviolet Radiation in the Sanjiang Plain

The variation characteristics of ultraviolet radiation (UV) in the Sanjiang region of Northeast China were analyzed using radiation data from 2005 to 2011. The temporal variation of the ratio of UV to broadband solar radiation (SR) was also analyzed. The results indicated that the temporal variation characteristics of UV and SR were similar. At the diurnal scale, the highest daily UV value was measured at noon, whereas the lowest was recorded in the morning or night. The highest monthly UV value was recorded in the summer, whereas the lowest in winter. In the Sanjiang region, the annual average daily UV was 0.53 MJ m^-2 d^-1. The variation characteristics of the UV and the ratio of UV to SR were the same. Daily, the highest value of the ratio of UV to SR was recorded at noon, whereas the lowest value was recorded in the morning or night. Yearly, the highest value was recorded in the summer, whereas the lowest in winter. The mean value of the UV to SR ratio was 0.0433 in this observation period of 2005-2011. Furthermore, an empirical equation for estimating the UV was established by using the in situ observations for 2011. The equation parameters include the relative optical air mass and clearness index. The equation can be widely used to obtain the UV from SR measurements. The largest relative error between observed and model UV data was 8.5% and 6.1% for instantaneous and daily values, respectively.