珠江三角洲地区大气气溶胶吸湿特性及其对光学性质的影响研究

The climate effect of aerosols is the largest uncertainty factor in the climate change study of the globe. Aerosols hygroscopicity affects their optical properties and their capability in activating to become cloud condensation nuclei, resulting in direct and indirect radioactive forcing effects of these aerosols.The observational study of hydroscopicity of aerosols is rather limited in mainland China, especially long-term, systematic studies.This project uses Hygroscopicity-Tandem Differential Mobility Analyzer(H-TDMA), Aethalometer, Nephelometer , aerosol ion composition analyzer, EC/OC analyzer, etc. to conduct a long-term study of aerosol hydroscopicity, optical properties and chemical characteristics at the same time over Pearl River Delta. It is also combined with Mie scattering model for a closure experiment of the optical properties of aerosols under dry, wet and ambient conditions. The project is expected to systematically give the growth factor and mixing state of aerosols in the Pearl River Delta area, including the variations in characteristics in diurnal scale, seasonal scale and different weather conditions. It also depicts the major factors affecting the changes in the hygroscopicity of aerosols. Based on the observational data and using the revised Mie scattering model, this project solves, verifies and assesses the optical properties of aerosol and the associated assumptions under different humidity conditions, displaying the effect of hygroscopicity on the optical properties of the aerosols. The results so obtained deepen our knowledge on the formation and transformation mechanisms of haze in the atmosphere of the Pearl River Delta area.

气溶胶的气候效应是全球气候变化研究中不确定性最大的因素。气溶胶吸湿性影响气溶胶的光学特性以及活化成为云凝结核的能力，影响气溶胶的直接和间接辐射强迫。目前国内对于大气气溶胶吸湿性观测研究相对缺乏，尤其是长期的、系统的研究更为缺乏。本项目拟使用气溶胶吸湿增长测量仪（H-TDMA）、黑碳仪、浊度计、气溶胶离子成分分析仪、元素碳/有机碳分析仪等设备，开展长期的珠江三角洲大气气溶胶吸湿性、光学特性和化学特性同步观测，并结合Mie散射模式组成干、湿、环境状态下的气溶胶光学闭合实验。项目预期能系统地表征珠三角地区大气气溶胶的吸湿增长因子和混合状态，包括日、季和不同天气条件下的变化特征，揭示影响气溶胶吸湿性变化的主导因素；基于观测数据，使用修正后的Mie散射模式组成光学闭合实验，求解、验证和评估不同湿度状态下的光学模型及相关假设，揭示气溶胶吸湿性对光学性质的影响。所得结果将深化珠三角地区大气灰霾形成和转化

气溶胶吸湿性影响气溶胶的光学特性以及活化成为云凝结核的能力，影响气溶胶直接和间接辐射强迫效应。本项目使用气溶胶吸湿增长测量仪（H-TDMA）、黑碳仪、浊度计、气溶胶化学成分分析仪、元素碳/有机碳分析仪、电迁移粒径分析仪等设备，在珠三角开展了多次外场观测试验，结合Mie模型、热动力平衡模型等手段，研究了此区域不同季节的气溶胶吸湿性特征及其成因、气溶胶挥发性特征与混合状态，分析了气溶胶数谱分布、液态含水量、化学组分与吸湿性之间的关系，定量计算了气溶胶吸湿性、相对湿度、混合状态对光学性质及直接辐射的影响。通过多次试验，积累了珠三角区域气溶胶吸湿性的季节变化数据。所得研究结果深化了珠三角地区大气灰霾形成和转化的认识。