北京地区重霾过程气溶胶颗粒密度分布及形貌因子演化的观测研究

气溶胶颗粒密度是连接其物理和化学特性的重要纽带，其形貌特征亦对其在大气环境的演化过程具有重要表征作用。申请项目拟以重霾污染过程为研究背景，基于外场观测和可控实验，构建气溶胶颗粒密度分布及形貌因子的拟合算法，定量表征城市大气复合污染条件下气溶胶颗粒表观密度及形貌因子演化过程和变化规律及其与气态前体物和气象要素的关系。进一步揭示气溶胶颗粒表观密度和形貌因子与其化学成分、粒径分布以及老化程度的内在关系，剖析重霾污染过程有机/无机成分对二次气溶胶颗粒形成的相对贡献，阐述重霾污染过程颗粒物快速增长的物理过程和化学机制，探索气溶胶颗粒形貌演化对其消光特性的影响，为制定霾污染调控策略和治理措施提供科学依据。

Aerosol particles have important effects on air quality, human health, climate, regional visibility, and the deposition of acidic and toxic substances. The properties of aerosol particles with respect to each of these issues are strongly affected by particle size distribution, morphology, and chemical composition. All of these properties may vary depending on the source and aging history of particles. For these complex properties of aerosol particle, the particle density can act as a good predictor and receive more and more concern recently. However, the majority of published work focuses on laboratory generated aerosols and obscuring a deeper understanding of the ambient particles. Atmospheric particulate pollution of Beijing is a major concern. Due to the industrial pattern and urbanization of Beijing, there are complex sources of primary aerosols which contain abundant chemical composition with great varying range. This project will first setup a comprehensive field experimental system coupled with laboratory experiments for studying the complex atmospheric transfer and evolution of aerosol particle during heavy haze pollution episodes in Beijing. Based on the measured physical and chemical characteristics of aerosol particles, the density and morphological evolution model will be constructed through numerical simulation. The density evolution of aerosol particle under multi-factor such as gaseous pollutants and meteorological parameters will be investigated. Relationship between density evolution and its morphology transformation will be explored based on the morphology model and some assumption, which are then used to determine the relative contribution of organic and inorganic components to the rapid formation of secondary aerosol during the heavy haze pollution episodes. This project will provide effective experimental data and theoretical support for understanding the aging mechanism of aerosol particle and its role in affecting light extinction in air pollution complex, and provide scientific guideline and theory evidence for policy makers to introduce suitable strategy under haze weather.