在中国地区，气溶胶作为云凝结核对于对流降水的影响不可忽视，但是影响对流降水的关键微物理过程以及路径是什么？目前尚不明确，回答该问题依赖于微物理参数化方案的可靠性，而它在中国地区缺乏飞机穿云观测廓线的评估。本研究选取了中国地区两种典型且水汽条件不同的对流降水类型，即华东夏季热对流降水和华北春季积层混合型对流降水，利用Weather Research and Forecasting（WRF）模式耦合Fast Version of Spectral Bin Microphysics Scheme（Fast-SBM）微物理方案，研究气溶胶充当凝结核对降水的影响，并使用质量/潜热收支逐步分解法，用于识别气溶胶影响降水的关键微物理过程以及路径。针对气溶胶影响对流降水的关键微物理过程以及路径，本论文的研究结果显示在水汽丰富的夏季热对流降水个例中，气溶胶增加能够促进降水。促进降水的关键微物理过程是云滴的凝结增长，关键路径是气溶胶增加提升了云滴数浓度和总表面积，增强了云滴凝结与云滴向雨滴的转化，同时凝结潜热的释放促进了上升气流，进一步加强了降水。而在水汽条件较低的华北春季对流降水个例中，气溶胶增加在云凝结核数浓度低于500/cm3时可促进降水，关键的微物理过程是雪晶的碰冻增长。关键路径为气溶胶增加促进云滴向0℃层以上的输送，进而增强了雪晶的碰冻增长和融化量。然而，当气溶胶浓度进一步增加时，降水反而减弱，原因是气溶胶增加抑制了云滴的凝结增长，并促进了云滴蒸发，这削弱了云滴向雨滴的转化。针对微物理参数化方案的飞机观测评估和改进，原始的Fast-SBM方案显著低估了华北春季积层混合型对流云个例中的冰相粒子数浓度和质量浓度，低估的主要原因是Fast-SBM方案对冰晶二次生成过程的处理缺失。本论文改进了该方案，改进后方案模拟的冰相粒子数浓度与观测值达到同一数量级，冰相粒子质量浓度的模拟偏差也显著改善。改进后的Fast-SBM方案也被用于研究气溶胶对该云降水个例的影响，提升了研究结果的可靠性。总的来看，本研究发展了一种分析气溶胶影响对流降水关键微物理过程的逐步分解法，并揭示了不同水汽条件下，云滴凝结增长对气溶胶影响降水的关键性作用，拓展了中国地区高污染环境下相关机理的认知。本研究也首次结合飞机观测与模拟，发现冰晶二次生成过程在华北春季对流云中起到了重要作用。通过改进Fast-SBM方案，解决了雪晶模拟偏低的问题，为改进该类型的云降水模拟提供了参考。
In China, aerosols acting as cloud condensation nuclei (CCN) exert a non-negligible influence on convective precipitation, yet the key microphysical processes and pathways involved remain poorly understood. Furthermore, modeling studies on aerosol impacts rely on the accuracy of microphysical parameterization schemes, which, in the context of China, have not been thoroughly evaluated using aircraft-based cloud profiling data. This study focuses on two representative convective precipitation types in China with distinct moisture conditions: summer convective precipitation in East China and spring stratiform-convective mixed precipitation in northern China. Using the Weather Research and Forecasting (WRF) model coupled with the Fast Version of Spectral Bin Microphysics Scheme (Fast-SBM), we investigate the effects of aerosols as CCN on precipitation. A novel decomposition method based on mass and latent heat budgets is proposed to identify and analyze the key microphysical processes and pathways through which aerosols affect precipitation. Additionally, aircraft cloud profiling data from a spring stratiform-convective mixed cloud case in northern China are employed to evaluate the reliability of the Fast-SBM scheme.The findings indicate that, in the moisture-rich case of summer convective precipitation, an increase in aerosols enhances precipitation. The key microphysical process is cloud droplet growth through condensation. Higher aerosol concentrations increase the cloud droplet number and total surface area, which in turn enhances droplet condensation and the conversion of cloud droplets into raindrops. The release of latent heat also strengthens updrafts, further intensifying precipitation. In the moisture-limited case of spring stratiform-convective mixed precipitation, aerosols promote precipitation when CCN concentrations are below 500 〖"cm" 〗^"-3" , with snow crystal riming growth being the key process. Aerosol increases enhance cloud droplet transport above the 0℃ level, boosting snow crystal riming and melting. However, when aerosol concentrations rise further, precipitation decreases, as higher aerosol levels suppress cloud droplet condensation and promote evaporation, reducing the conversion of droplets into raindrops.Regarding the evaluation and improvement of the microphysical parameterization scheme, the original Fast-SBM significantly underestimated ice particles’ number and mass concentrations in the northern China spring stratiform-convective mixed cloud case. This underestimation was largely due to the scheme's limitations in modeling secondary ice generation processes. The improved scheme brought simulated ice particles’ number concentrations in line with observed values and significantly reduced the bias in its mass concentrations. The modified Fast-SBM scheme was further applied to study aerosol effects on this cloud system, enhancing the reliability of the findings.This study develops a novel decomposition method to dissect the key microphysical processes influenced by aerosols, highlighting the critical role of cloud droplet condensation growth in modulating convective precipitation across varying moisture conditions. This work extends the understanding of aerosol-cloud-precipitation interactions, particularly in high-pollution environments in China. Furthermore, by integrating aircraft observations with model simulations, the study uncovers the pivotal role of secondary ice generation in northern China's spring convective clouds. The improvements to the Fast-SBM scheme, addressing the underestimation of snow crystal concentrations, provide a valuable framework for enhancing cloud and precipitation simulations in similar cloud systems.
