中国东部地区气溶胶污染比较严重，低能见度和气溶胶辐射效应等都与气溶胶的吸湿特性密切相关。气溶胶的吸湿特性已经成为气溶胶观测的热点内容之一。本项目拟研发一套高时间分辨率的气溶胶光学吸湿增长因子测量系统，并开展华北地区气溶胶光学吸湿特征的观测研究。该系统采用可控制相对湿度的加湿单元，加湿单元中最为核心的水汽渗透管为ePTFE材料。这套系统具有时间分辨率高，可精确控制相对湿度等优点。利用该系统，我们将在华北地区开展高时间分辨率的气溶胶光学吸湿特征的观测研究，分析气溶胶化学组分和光学吸湿特性之间的关系。该项目的完成不仅可以提高目前气溶胶观测的能力，而且观测结果有助于进一步开展气溶胶辐射强迫研究和大气能见度研究。

Eastern China suffers from heavy aerosol pollution and the low visibility and aerosol radiation effect are strongly dependent on the aerosol hygroscopicity. The hygroscopic properties have become one of the most popular issues for aerosol measurements. This proposal aims to develop a new measurement system for aerosol optical growth factor with high time resolution. The advantages of this system are high time resolution for measurement and high accuracy for relative humidity controlling. This system will join a field campaign in the North China Plain to measure optical hygroscopic properties together with some other aerosol- monitoring equipments. Statistical analysis of hygroscopic growth factor in the North China Plain will be made together with the meteorological data. A closure study between growth factor measurement and aerosol hygroscopicity derived from chemical data will be carried out. The results from this proposal may make us better understand aerosol physical properties and promote the research on aerosol radiative forcing and visibility forcasting.