• 关键词：光合有效辐射  水汽  散射因子  能量  化学和光化学反应

• 基金项目：中国科学院野外台站研究基金

• 白建辉
• 中国科学院大气物理研究所中层大气与全球环境探测重点实验室, 北京 100029

• 摘要：2004年9月～2006年10月,在华北地区的4个站点开展了太阳辐射、气象参数等的综合观测,得到了光合有效辐射PAR、总辐射Q等的变化特征.水汽和散射因子对于PAR/Q和PAR有明显的影响.基于能量观点,建立了实际天气PAR小时累计值(时累)的经验模式,获得了较好的计算结果.水汽因子对于PAR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PAR以及占地面PAR的比例分别为7.99W·m^-2和4.24%,受散射因子衰减到达地面的PAR以及占地面PAR的比例分别为172.36W·m^-2和95.76%.华北地区受水汽因子和散射因子影响损失于大气中PAR分别为15.33、309.30W·m^-2,这一能量损失表现出明显的季节变化和区域差别.敏感性实验表明,地表PAR对于水汽因子、散射因子的变化有不同的响应,PAR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PAR之间的关系与水密切相关,水汽因子项的真正含义应该是大气中的各种物质成分(气、液、固态)对于PAR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PAR经验模式计算了大气顶的PAR,计算误差为-3.5%.在目前及未来研究中,应该重视和考虑消耗于大气中的且与水汽有关的这部分能量.基于能量观点分析实测资料并研究大气中的物理化学过程及其规律是一种行之有效的方法.

• Abstract：Integrated observations were made of solar radiation and meteorological parameters at 4 stations in North China from September 2004 to October 2006,and the variation of photosynthetically active radiation (PAR) and global radiation (Q) were obtained.Both PAR/Qand PARwere evidently influenced by water vapor and scattering factors.An empirical model of hourly PARunder actual sky conditions was established based on the point of view of energy,and good calculated results were gained.The water vapor factor plays an important role in PARtransmission in the atmosphere and should be considered carefully.The results show that for North China,PARat the Earth's surface attenuated by the water vapor factor and its ratio to PARat the Earth's surface were 7.99 W·m^-2 and 4.24%,respectively,while PARat the Earth's surface attenuated by the scattering factor and its ratio to PARat the Earth's surface were 172.36 W·m^-2 and 95.76%,respectively.PARlosses influenced by the water vapor factor and the scattering factor in the atmosphere are 15.33,309.30 W·m^-2 in North China,respectively.This energy loss displayed evident seasonal variations and regional differences.The sensitivity test shows that PARdisplayed different responses to different changing rates of water vapor factor and scattering factors.PAR is more sensitive to the change of scattering factor than that of the water vapor factor.The relation of the water vapor factor and PAR indicated a close relationship with water;the real meaning of water vapor (item) is the sum of direct absorption and indirect absorption (in the reactions of chemistry and photochemistry,including homogeneous and heterogeneous processes) by all kinds of substances (including gases,liquid and solids) in the atmosphere.PARat the top of the atmosphere was calculated by the empirical model,with an error of-3.5%.The energy consumed in the atmosphere is related to water,which should be paid more attention in present and future study.Analyzing observational data from the point of view of energy is an effective method to study physical and chemical processes and their effects in the atmosphere.

• Key words：photosynthetically active radiation (PAR)  water vapor  scattering factor  energy  chemical and photochemical reactions

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