中国中东部气溶胶粒子谱分布形成机理及微物理混合机制的数值模拟研究

Fine particles pollution has caused significant effects on climate and environment in regional scale over Central-eastern China. Direct radiation effect and impact on clouds of aerosol particles are largely dependent on their number-size distribution and mixing state. Particles with different size and mixing state have different effects on visibility and human health. Air quality models widely used in scientific world have some deficiencies and it is difficult to simulate particles number-size distribution and mixing state in detail simultaneously. There are large uncertainties in simulation of particles number-size distribution and mixing state. Given these reasons, this study will establish an advanced air quality model describing aerosol particles microphysics and chemistry in a mechanism way on the basis of the self-developed air quality model including detailed aerosol microphysics processes. The model will be improved in the description of fine particles growth and mixing processes in advantage of detailed characterization in aerosol microphysics of the model. Mechanism of particles number-size distribution formation and the microphysical mixing processes in modifying mixing state of aerosol particles will be elucidated in depth by the improved model. Also, the spatial and temporal distribution of particles number-size distribution and mixing state will be presented. The research results achieved in this study can be expected to provide scientific support in pollution regulation and evaluating climate and environmental effects caused by particles pollution in central-eastern China.

我国中东部地区大气细颗粒物污染对区域尺度的气候和环境造成了重要影响。气溶胶颗粒的直接辐射效应和对云的影响与粒子谱分布和混合状态密切相关，不同粒径、不同混合状态的粒子对能见度和人体健康的影响显著不同。国际上主流模式对粒径谱分布和混合状态的表征存在一定的不足，在模式中同时对粒子谱分布和粒子混合过程进行精细模拟十分困难，粒径谱分布和混合状态的模拟存在很大不确定性。鉴于此，本项目拟以自主研制的包含气溶胶详细微物理过程的空气质量模式为基础，利用该模式在气溶胶微物理过程精细表征方面的优势，进一步改进模式对粒子增长和混合老化过程的描述，建立一个更加精细的空气质量模式。利用该模式，深入剖析我国中东部气溶胶粒子谱分布形成机理、解析微物理混合机制，给出我国中东部气溶胶粒径谱分布、混合状态等关键参数的时空分布，为该地区细粒子污染治理及气溶胶气候和环境效应的评估提供科学支撑。

我国中东部地区大气细颗粒物污染对区域尺度的气候和环境造成了重要影响。气溶胶颗粒的直接辐射效应和对云的影响与粒子谱分布和混合状态密切相关，不同粒径、不同混合状态的粒子对能见度和人体健康的影响显著不同。国际上主流模式对粒径谱分布和混合状态的表征存在一定的不足，在模式中同时对粒子谱分布和粒子混合过程进行精细模拟十分困难，粒径谱分布和混合状态的模拟存在很大不确定性。鉴于此，本项目以自主研制的包含气溶胶详细微物理过程的空气质量模式为基础，进一步改进了模式对有机气溶胶形成过程和其微物理过程的描述，耦合了有机物参与核化的核化速率计算方案，有效地改进了模式对新粒子形成事件的模拟能力；利用该模式，详细解析了典型城市大气气溶胶粒径谱分布形成机理，量化了一次排放和二次核化对不同大小粒径气溶胶数浓度的贡献；本项目还建立了基于气溶胶微物理参数的非均相反应方案和黑碳气溶胶老化速率计算方案，合理地估算了黑碳气溶胶老化时间并给出了亲水和疏水性质的黑碳气溶胶比例，促进了对黑碳气溶胶混合状态和湿沉降特征的精确表征。本项目的研究结果可为我国中东部大气细粒子污染治理及气溶胶气候和环境效应的评估提供科学支撑。