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利用飞机PMS探测数据、雷达回波资料和FY-2卫星云图,分析了2009年6月四川盆地上空一次未形成地面降水的多层云系。结果表明,云系为Cs-As2-As1-Sc2-Sc1结构,夹有干层。云系中暖层厚,过冷层很薄。液态含水量随高度分布很不均匀,出现多个峰值。云系中液态含水量主要由小云粒子浓度决定,并且存在大量的小云滴、一些大云粒子、很少的降水粒子和稀少的冰晶,粒子的垂直分布很不均匀。云系内缺乏足够的冰晶作凝结核,不含过冷水,冷云过程对降水粒子的形成贡献很小。在中低层的暖云过程,由于As2很弱,As1缺乏大滴,云雨转化主要依靠耗时相当长的凝结增长,降水粒子没有落出As1云底。Sc2中发生了凝结增长和碰并增长,但是由于降水粒子主要集中在小粒子端,大粒子相当少,云雨转化的速度不快、效率不高,降水粒子未能穿过夹层影响到底层的Sc1。云系底层的Sc1没有形成〉300μm的降水元,未能形成地面降水。“,”Using the PMS flight detection data,radar echoes data and FY-2 satellite cloud image,a deep multi-layer cloud system without ground precipitation in June 2009 is analyzed.The cloud system is a Cs-As2-As1-Sc2-Sc1 structure with dry layer.The result shows that in the cloud system the warm layer is deep while the super-cooled layer is very thin.The liquid water distributes quite unevenly with height,showing several peak values.The liquid water content in the multi-layer cloud system is mainly determined by the number concentration of small cloud particle.There are a number of small cloud droplets,a few large cloud particles,a small quantity of precipitation particles and scarce ice nuclei.The vertical distribution of particle is very uneven.The lack of enough ice nuclei take as condensation nuclei in the multi-layer cloud system,while super-cooled water does not exist in the multi-layer cloud system,as well as the thick dry layer between Cs and As2 obstructs the falling of ice nuclei,the cold cloud process contributes little in the forming of precipitation particles.In the warm cloud process in the middle layer and the low layers,because As2 is weak,and so the large droplets in As1 are lack,precipitation particles form from cloud droplets mainly through tardy condensation growth,so that precipitation particles never fall through the base of As1.In Sc2 precipitation particles form from cloud droplets through condensation and collection growth.However,the precipitation particles in Sc2 are mainly small particles,and large particles are limited.The transforming speed and efficiency from cloud droplets to precipitation particles is slow.Precipitation particles could not pass the dry layer to impact Sc1.And Sc1 has not yielded particles larger than 300μm.Finally,the deep cloud system has not formed ground precipitation.