夹卷混合过程及其影响因子对云内过饱和度的影响  

Effects of Entrainment-Mixing Process and Its Impact Factors on Cloud Supersaturation

作　　者：刘文惠 罗仕 陆春松[1] 赵阳[1] LIU Wenhui;LUO Shi;LU Chunsong;ZHAO Yang(Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters,Nanjing University of Information Science and Technology,Nanjing 210044;College of Aviation Meteorology,Civil Aviation Flight University of China,Sichuan,Guanghan 618307)

机构地区：[1]南京信息工程大学中国气象局气溶胶与云降水重点开放实验室/气象灾害预报预警与评估协同创新中心,南京210044 [2]中国民用航空飞行学院航空气象学院,四川广汉618307

出　　处：《气象》2023年第5期551-562,共12页Meteorological Monthly

基　　金：国家重点研发计划(2019YFA0606803);国家自然科学基金项目(42175099、42027804);中央高校基本科研业务费基金项目(J2022-037)共同资助。

摘　　要：云内过饱和度是影响云宏微观物理特性的关键之一。利用显式混合气泡模式,首先研究了云滴周围过饱和度在夹卷混合过程中的演变特征,结果表明:过饱和度先因干空气作用减小,后因云滴蒸发作用增大,直到气块恢复饱和。随后分析了不同的热力、动力和微物理因子对过饱和度的减小幅度和饱和恢复快慢程度的影响。敏感性试验表明:减幅小、恢复快的因子是较大的卷入空气相对湿度和初始云滴数浓度;相对湿度越大,夹卷的影响越小;数浓度越大,云滴尺度越小,蒸发越快,对湿度的补充越强。减幅大、恢复慢的因子是较大的卷入空气比例;卷入空气越多,蒸发量越大。减幅大、恢复快的因子是较大的湍流动能耗散率;混合过程越快,云滴蒸发越快。研究结果有助于提升对夹卷混合过程和暖云降水理论的理解。Supersaturation in the cloud is the one of key factors affecting cloud macro-and micro-properties.The Explicit Mixing Parcel Model(EMPM)is used to study the evolution of supersaturation of cloud droplets during the entrainment-mixing process.The results show that in this process,the supersaturation decreases firstly due to the entrained dry air,and then increases due to the evaporation of droplets until the parcel restores new saturation.Then,the effects of different thermal,dynamic and microphysical factors on the reduction of supersaturation and saturation recovery time are analyzed.The sensitive test indicates that the factors of small reduction and quick recovery are the high relative humidity of the entrained dry air and the number concentration of initial cloud droplets.The higher humidity,the less effect of entrainment.The higher the number concentration,the smaller droplet size and the faster evaporation,and thus the supplement to the humidity of dry air is strong.The factor of large reduction and slow recovery is the large fraction of entrained dry air.The more the dry air is entrained,the more evaporation of droplets.The factor of large reduction and quick recovery is the high turbulent kinetic energy dissipation rate.The faster the mixing process,the faster cloud droplets evaporate.The results will help to improve the understanding of the entrainment mixing process and warm cloud precipitation theory.

关 键 词：云物理 夹卷混合过程 过饱和度 数值模拟 

分 类 号：P426[天文地球—大气科学及气象学] P421