中文摘要：

本文利用耦合了CAMS云微物理方案的WRF中尺度模式的模拟结果结合飞机、卫星、雷达、地面雨量等观测资料,对2012年9月25日山西一次低槽弱冷锋降水层状云系的宏微观结构和过冷水分布特征进行分析,试图研究低槽冷锋层状云系结构特征及过冷水形成的宏微观条件,为人工增雨作业提供依据。模拟的天气形势、降水、云顶温度、雷达回波、水成物的演变与实测基本一致。结果表明：此次降水过程的系统为低槽弱冷锋,且锋面后倾,位于锋前的云系前部为高层冷云,云顶温度-40℃左右,以冰相粒子组成,没有降水;锋区云系变成高层冷暖混合云,冷区以少量过冷水和大量冰相粒子组成,地面降水最大;处于锋后的云系后部为高层冷云,云顶温度-30℃左右,不存在过冷水,以较少冰相粒子组成,地面降水较弱。过冷水主要分布在锋面前方低于-5℃层,高度偏低、含量偏少,过冷水一方面因垂直上升速度供应水汽维持,另一方面因冰相粒子的凝华而消耗。过冷水层及其下部上升运动较弱、而其上部上升运动较强,不利于在过冷区长时间维持大量液态水,反而促使冰相粒子发展旺盛,此处水汽相对水面不饱和、相对冰面饱和,大量冰相粒子消耗水汽,不利于过冷水的存在,导致云场仅存在少量过冷水。本次过程中,冰核浓度的增大仅增大冰晶浓度,对雪霰含量及-5~0℃的过冷水几乎没有影响。

英文摘要：

Based on WRF mesoscale model which couples CAMS cloud scheme with cloud microphysics process,a low trough cold front precipitation process that occurred on 25 September 2012 in Shanxi Province was simulated.According to the simulation results,the macro and micro cloud structure and supercooled water distribution were analyzed combining with other data,such as aircraft detection,satellite,radar and ground rainfall observations.The structure and physical condition of supercooled water were studied so that seeding suggestions could be provided in this kind of cloud system.The simulated weather situation,precipitation,cloud top temperature,radar echo distribution,and hydrometeors evolution are basically consistent with the observations.The main results are as follows.This precipitation process was influenced by a low trough cold front system in front of which high and cold cloud was composed of ice particles.The cloud top temperature was about-40℃,and no precipitation on surface.Near the front,clouds were mixed by warm and cold particles.The cold cloud zone was made up of small amount of supercooled water and large quantity of ice particles,with heaviest precipitation on the surface.Behind the front,high and cold cloud had a small amount of ice particles,no supercooled water.The cloud top temperature was about-30℃ and the surface rain was light.The supercooled water was mainly distributed in the-5℃ layer in front of the front.Showing the characteristic of lower height and smaller content,the supercooled water was hold by water vapor through the vertical updraft on one hand,and consumed by ice particles sublimation growth process on the other hand.The updraft condition,which in and under supercooled water layer was weak and over it was strong,was not beneficial to the maintenance of large amount of liquid water,but promoted ice particles to develop quickly.In this area,water vapor is not saturated with respect to liquid water but saturated to ice.The water vapor was consumed by a lot of ice particles,not favorab