1、北京市区大气气溶胶散射系数亲水增长的观测研究 颜鹏 1，2 潘小乐 3 汤 洁 3 周秀骥 3 曾立民 41中国气象科学研究院，北京 1000812. 北京大学大气科学系，北京 1008713中国气象科学研究院，北京 100081 4北京大学环境学院，北京 1000871摘 要利用自制的“进样气流湿度调节”装置，在 2005 年 12 月 722 日在中国气象局科技大楼测点（记为 CAMS）对北京市区冬季气溶胶散射系数随湿度的变化关系进行了观测试验，结果显示，观测期间北京市区气溶胶散射系数亲水增长因子（定义为一定湿度下的气溶胶散射系数与“干”气溶胶散射系数的比值）在湿度从低到高的变化过程中，主
2、要表现出“平滑连续”的增长特点。总体上，当相对湿度从小于 40增大到大约 93时，平均气溶胶散射系数亲水增长因子可达 2.10，而在相对湿度 80时的平均散射系数亲水增长因子f(RH=801%)大约为 1.260.15。按照污染情况和天气过程把观测期间划分为 “相对污染”时段和“清洁”时段，则在“相对污染”情况时，北京市区 CAMS 测点的气溶胶散射系数增长因子 f(RH=80%)大约为 1.48，而在“清洁”时段约为 1.2。与国外有关观测相比，北京冬季“清洁”时段气溶胶的散射系数亲水增长因子 f(RH=80%)在数值上与生物质燃烧型和扬尘类型气溶胶的亲水增长相似。反映了在不同天气背景下北京
3、市区的气溶胶类型有不同的特点。关键词 湿度调节装置,气溶胶散射系数, 亲水增长因子。资助课题：中国气象局气候专项（CCSF2005-3-DH03） ，科技部公益项目“我国大陆大气本底基准研究” （G99-A-08） 、国家自然科学基金重大国际合作项目 “我国东部大气气溶胶理化和光学特性观测研究”项目（49899270） 。作者简介： 颜鹏，从事大气物理和大气环境方面的观测研究和数值模拟，近年来主要研究大气气溶胶及其辐射效应，以及气溶胶与云的相互作用等。Email: 2007-01-31 收稿,2007-04-06 改回.中图法分类号 P402An experimental study on
4、the influence of relative humidity on the atmospheric aerosol scattering coefficient at an urban site in beijingYan Peng1,2 Pan Xiaole1 Tang Jie1 Zhou Xiuji1 Zeng Limin31.Chinese Academy of Meteorological Science, Beijing 1000812. Atmospheric department, Peking University, Beijing 10008713.College o
5、f Environmental Science, Peking University, Beijing 1000871AbstractThe humidity-controlled aerosol measurement system was developed to study the hygroscopic properties of aerosols. The system included a humidity-controlled inlet to humidify the sample air, and two nephelometers to simultaneously mea
6、sure the aerosol scattering coefficients under “dry” and “wet conditions. During the measurement, the air passed through the inlet and was humidified by the water vapor diffusing through the wall of the membrane tube. The method used to adjust the amount of water vapor, was called the “combination o
7、f water vapor addition and/or thermal control” method, was realized by controlling the temperature of water out of the membrane tube. Using this system, the experimental study on the hygroscopic growth of aerosol scattering coefficients at an urban site (CAMS) in Beijing city was conducted from Dece
8、mber 7 to 22, 2005. The instrument was installed on the roof of a building on the campus of Chinese Meteorological Administration in the northwest of Beijing urban area, and the inlet of the instrument was about 50 m above the ground. The preliminary analysis of the measurements indicate that: overa
9、ll, the hygroscopic growth factor of the scattering coefficient f(RH) increased continuously when the RH increased. the average growth factor f(RH) of the aerosols for the whole measurement period could reach to 2.1 when RH increased from less than 40% to 93. The average hygroscopic growth factor at
10、 relative humidity of 80%, f(RH=801%), was about 1.26 0.15. Further calculation shows that the hydroscopic growth factor f(RH) was relatively higher when the air was relatively polluted, where, the f(RH) at RH=80% was about 1.48, however, when the air was clean, the growth factor f(RH) at RH=80% was
11、 about 1.2. The growth factor f(RH) for relatively polluted case was lower than the result reported by Carrico (Carrico et al.,2003), f(RH=82%)2.220.20, for polluted aerosol type during the Ace-Asia experiment, but the behavior of the hydroscopic growth under clean air conditions was similar to thos
12、e influenced by burning biomass or blowing dust as reported (Carrico et al., 2003; Kotchenruther et al, 1998). These results reflect the different characteristics of aerosol types at Beijing urban area under the different air conditions in the winter.Key words humidifier, aerosol scattering coefficient, hygroscopic growth factor
