大气气溶胶相态及其对二次有机气溶胶浓度及粒径分布影响的模拟研究

二次有机气溶胶(SOA)是细颗粒物的主要组分，目前大气化学输送模式对SOA物理化学属性的模拟有很大不确定性，进一步理解SOA生成机制及其物理化学属性的模拟是当前气溶胶研究的薄弱点和难点。相态是SOA的重要属性，对SOA气-粒转化、气溶胶粒径分布、多相化学及污染物长距离输送等有显著影响。目前国内外对SOA相态的研究多集中于外场观测与实验室研究，对相态的模拟研究还很薄弱。我们之前的研究发展了利用挥发性预测有机气溶胶相态的方法，本项目拟将此方法耦合入区域空气质量模式WRF-Chem并模拟京津冀冬夏两季SOA的相态；量化无机气溶胶贡献的液态水对SOA相态的影响；用基于动力平衡的气−粒转化方案改进SOA生成机制的模拟；结合分层动力学模式KM-GAP量化气溶胶相态对SOA浓度以及粒径分布的影响。将SOA相态引入空气质量模式是国内外为数不多的新尝试，是对SOA物理化学属性及生成机制模拟的进一步完善。

Secondary organic aerosol (SOA) is a major component of atmospheric fine particles. Currently large uncertainty has been found in representations of SOA physicochemical properties within atmospheric chemical transport models. A better understanding of SOA formation mechanisms and proper representation of SOA physicochemical properties are critical issues. Phase state is an important physical property of SOA, playing an important role in gas-particle partitioning, particle size distribution, multiphase chemistry and long-range transport of persistent organic pollutants. While many field observations and laboratory experiments have been conducted characterizing aerosol phase state, there are a few efforts made for simulations of phase state. Our previous study has developed parameterizations predicting SOA phase state using volatility distributions. This project will couple these parameterizations into the regional air quality model WRF-Chem and simulate SOA phase state over the Beijing-Tianjin-Hebei region in winter and summer. We will evaluate the impacts of the particle liquid water associated with inorganic components on SOA phase state. Kinetic treatments of gas-particle partitioning will be applied to improve the simulations of SOA formation in the WRF-Chem model. Combined with the results of a kinetic multi-layer model KM-GAP (kinetic multi-layer model of gas–particle interactions in aerosols and clouds), how the phase state affects SOA concentrations and particle size distributions will be addressed. The simulation results will be validated against available field observations. This project is one of the first tries coupling SOA phase state into three-dimensional air quality models, which will improve the representations of SOA properties and formation mechanisms.