切变线降水系统微物理特征及降水机制个例分析

Analysis of Micro-Physical Structure Characteristics and Precipitation Mechanisms of a Shear-Line Precipitation Case in Jilin Province

利用机载云粒子探测系统(PMS),对2004年7月1日影响吉林省的一次切变线降水过程进行了探测飞行,利用所获取的宏微观资料对此次降水过程的微物理结构、降水机制进行综合分析。结果表明:此次切变线降水云系主要由高层云、雨层云、碎云构成,高层云和雨层云中间夹有1100 m左右的无云区;3类云中平均云滴浓度、平均云滴直径各不相同;云水含量随高度分布不均匀,云的不同部位云水含量起伏较大;冰晶浓度平均为17.3个/L;此次探测的降水云系符合Bergeron提出的催化云-供水云相互作用导致降水的概念。根据云图及其他探测资料综合分析,冰晶主要产生于高层云上部或卷层云的冰晶播撒,供水云为高层云中下部和雨层云。

A composite sounding flight was made during a shear-line precipitation process in Jilin Province on 1 July 2004. The micro-physical structure, precipitation mechanisms of this precipitation process are analyzed by means of the airborne Particle Measuring System （PMS） data, and the micro-physical structure characteristics of the shear-line precipitation cloud system and the physical mechanisms of rainlall formation are analyzed compositely. The results show that this shear-line rainfall clouds mainly consist of altostratus, nimbostratus, and fractus; the average cloud droplet concentration and average cloud droplet diameter are different in three kinds of clouds; the cloud water content is distributed unevenly with increasing height; and the different parts of the clouds have different cloud water contents. The precipitation cloud system measured by PMS conforms to the concept of Bergeron seeder-feeder cloud mechanism. The comprehensive analysis of cloud pictures and other sounding data shows that ice crystals mainly appeared in the upper part of altostratus or resulted from the spreading of ice crystals in cirrostratus, and feeder clouds are the central and lower parts of altostratus and nimbostratus.