基于光学特性测量的气溶胶吸湿增长因子观测研究

项目名称： 基于光学特性测量的气溶胶吸湿增长因子观测研究

项目编号： No.41475118

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 天文学、地球科学

项目作者： 孙俊英

作者单位： 中国气象科学研究院

项目金额： 94万元

中文摘要： 气溶胶吸湿增长对能见度和气溶胶的辐射强迫有重要的影响，而且具有很大的不确定性。目前国内有关基于气溶胶散射系数测量的吸湿增长因子的观测结果还较少，仅有的一些观测也多是基于单波段浊度仪的观测。本项目拟在我国经济比较发达的长三角地区的背景区域，使用三波段的积分浊度仪，同步观测干状态和可控相对湿度下气溶胶的散射特性，获得吸湿增长因子观测资料，分析气溶胶吸湿增长因子随相对湿度的变化趋势及其与测量波长的关系，探讨气溶胶吸湿增长因子的变化规律，获得气溶胶辐射强迫计算中关键参数如后向散射比、单次散射反照率等的变化，评估这些参数对辐射强迫计算的影响。结合气溶胶质谱测量的化学成分及其粒径分布资料，探讨气溶胶吸湿增长因子及其与化学成分的关系，为改进区域气候模式/辐射传输模式中的气溶胶辐射特性参数、减少辐射强迫计算中的不确定性提供科学基础。

中文关键词： 气溶胶；吸湿增长；光学特性；化学成分

英文摘要： Hygroscopic growth of aerosols has an important impact on visibility and radiative forcings and poses very large uncertainty. Hygroscopic aerosols take up water as humidity increases. Aerosol water matters since water can affect both the size and refractive indices of atmospheric aerosols, thereby influencing the mass concentration, size distribution, and corresponding optical properties (e.g., scattering coefficient, backscattering coefficient, single scattering albedo, and asymmetry parameter. In particular, understanding the effect of relative humidity on aerosol light scattering is important to better estimate the radiative effect and evaluate the visibility impairment. This study will carry out the intensive field campaign at Lin'an station, which is a WMO GAW regional station (30.3 N, 119.73 E, 138m a.s.l.) located in the center of Yangtze River Delta, China. The hygroscopic growth factor is defined as the ratio of aerosol scattering coefficient at a given RH to that at a low reference RH (<40%). Correspondingly, the measurement system involves two nephelometers operating in series with a humidifier in the middle of them. Sample air enters the first nephelometerthrough an aerosol dryer, which controls the sample RH lower than 30%, then passes through the humidifier, where the sample RH is regulated to a higher RH ranging from 40% to 90%, and finally enters the second nephelometer (humidified nephelometer or WetNeph, TSI Inc., Model 3563) where the scattering coefficient of humidified aerosols are measured. We will study the variation of hygroscopic growth factor with different chemical, different wavelength. We will also investigate the systematic variation of the important parameters to radiative forcing. This study will help us understand more about the how the hygroscopic growth factor and optical properties effects the radiative forcing and visibility, and provide the fundamental data to improve the parameterization in the regional climate mode.

英文关键词： Aerosols;Hygroscopic Growth;Optical properties;Chemical Composition