山东禹城紫外辐射变化特征及其估测方程的建立

本文对2005～2011年山东禹城地区观测得到的紫外辐射的时间变化特征及紫外辐射与总辐射比值的变化特征进行了分析, 并结合气温、降水和露点温度资料建立了禹城地区的紫外辐射估测方程。结果表明:紫外辐射日累计值的变化范围为0.10～1.20 MJ m-2 d-1, 年平均值为0.468 MJ m-2 d-1;紫外辐射日、季节变化规律与总辐射一致, 季节变化都表现为冬季小夏季大, 最小值出现在1月, 最大值出现在6月, 日变化则呈现早晚小中午大的特征;紫外辐射与总辐射的比值范围为0.023～0.046, 其季节变化特征也是冬季小夏季大, 该比值随晴空指数的增大而减小, 而在晴空指数大于0.5时比较稳定。利用温度日较差(日最高气温与最低气温的差值)建立了紫外辐射估测方程, 决定系数R2达0.80, 平均相对误差为0.19, 估测紫外线等级与实测紫外线等级相差不大于1的数据占95%, 该方法可以较好地进行紫外辐射等级的估测。

Variation Characteristics and Establishment of EstimatingEquation for Ultraviolet Radiation in Yucheng, Shandong Province

The temporal variation of ultraviolet (UV) radiation and the ratio of UV radiation to broadband solar radiation were analyzed in Yucheng using the radiation observations of 2005-2011, and the estimating equation of UV radiation was established using the data of air temperature, precipitation, and dew point temperature. The results showed that the UV radiation has consistent variation characteristics with solar radiation; the cumulative value range was 0.10-1.20 MJ m^-2 d^-1, and the average value was 0.468 MJ m^-2 d^-1. The highest and lowest values of monthly UV radiation were measured in June and January, respectively. The highest value of daily UV radiation was measured at noon, and the lowest value occurred in the morning or at night. The range of the ratio of UV radiation to solar radiation was 0.023-0.046. The seasonal highest and lowest ratios of UV radiation to solar radiation occurred in summer and winter, respectively. The ratio reduced as the clearness index increased, and the ratio was relatively stable when the clearness index was greater than 0.5. Finally, a UV radiation estimating equation was established by using temperature and precipitation. The determination coefficient R² was 0.80, and the mean bias error was 0.19. There are 95% data the difference in observed and estimated values was less than 1 level. Thus, the equation is appropriate for estimation.