以能量方法研究紫外辐射在大气中的传输

Studying the transmission of solar UV radiation in the atmosphere from the point of view of energy

2004年9月～2006年10月,在华北地区4个站点开展了太阳辐射、气象参数等综合观测,得到了紫外辐射UV、总辐射Q等的变化特征.水汽和散射因子对于UV/Q和UV有明显影响.建立了实际天气UV小时累计值(时累)的经验模式,得到了较好的计算结果.水汽因子对于UV在大气中的传输有一定的作用,应给予重视.计算表明,华北地区受水汽因子衰减到达地面的UV以及占地面UV的比例分别为15.00W.m-2和37.45%,受散射因子衰减到达地面的UV以及占地面UV的比例分别为23.89W.m-2和62.55%.华北地区受水汽因子和散射因子影响损失于大气中的UV分别为19.30、35.31W.m-2,这一能量损失表现出明显的季节变化和地区差异.敏感性实验表明,地表UV对于水汽和散射因子的变化有不同的响应,UV对散射因子的变化比对水汽因子的变化更敏感.水汽因子与UV之间的关系与水密切相关,水汽项的真正含义是大气中各种物质成分(气、液、固态)对于UV的直接吸收和间接利用(通过化学和光化学反应,包括均相和非均相过程)的总和.利用经验模式计算了大气顶的UV,计算误差为+7.83%.未来研究中应重视和考虑消耗于大气且与水汽有关的这部分能量.以能量观点分析实测资料并研究大气中的物理化学过程是一种行之有效的方法.

Solar radiation and meteorological parameters were measured at 4 in-situ stations in North China from September 2004 to October 2006,and the variability of solar ultraviolet radiation （UV） and global radiation （Q） was recorded at the same time. Previous studies showed that both UV/Q and UV were significantly influenced by water vapor and scattering factors. An empirical model of hourly sum of UV under all sky conditions was established,and good results were obtained. In addition,water vapor factor played an important role in UV transmission in the atmosphere. The results show that in North China,UV reaching the Earth＇s surface by the attenuation of water vapor factor is just 15.00 W·m^-2which contributes about 37.45% of surface UV. By the attenuation of the scattering factor,UV reaching the Earth＇s surface is 23.89 W·m^-2which contributes about 62.55% of surface UV.UV losses due to the attenuation by water vapor and scattering factors in the atmosphere were 19.30 and 35.31 W·m^-2in North China,respectively. This energy loss shows an obvious seasonal and spatial variability. The sensitivity tests demonstrate that UV has different responses to the changing rates of water vapor factor and scattering factors,and UV is more sensitive to the scattering factor than to water vapor factor. The relationship between water vapor and UV showed a close relation with water,and actually,the water vapor factor is the sum of direct absorption and indirect consumption （during the chemical and photochemical reactions,including homogeneous and heterogeneous processes） by all components （including gases,liquid and solids） in the atmosphere. UV at the top of the atmosphere was calculated by using the empirical model,and its error is about ＋7.83%. The energy loss in the atmosphere is related to water,and should be paid more attention in future study. Thus,analyzing the observational data from the angle of energy is an effective method to study physical and chemical processes in the atmosphere.