青海秋季对流云降水及催化过程数值模拟研究

Simulation Study on the Precipitation and Seeding Process of Convective-cloud in Qinghai with a 3D Cloud Model

利用CAMS三维对流云模式和青海省河南县秋季外场试验取得的资料,对自然云的发展演变过程进行了数值模拟试验。进一步就催化时间、催化剂量对增雨效果的影响进行了数值试验。结果表明,该地区秋季对流云降水主要为冷云降水,冰晶是霰产生的主要来源,冰霰自动转化是霰产生的最主要方式,冰晶与霰的碰并又促进了霰的进一步增长,霰是云中过冷水消耗的主要因素。人工播撒催化剂应在冰核活化过程大量开始以前进行,以达到增加冰晶浓度,消耗过冷云水,从而增加降水的目的。

On the basis of the sound data obtained from the autumn field experiment in 2002 in Henan country of Qinghai province,and in terms of the 3D cloud-model of CAMS,the paper studies the natural cloud development and simulates the effect of seeding time, seeding position and seeding amount on precipitation enhancement. The study shows that the precipitation in the experiment area is dominated by cold cloud precipitation processes and the ice crystal is the main source of grauple, which is produced by the auto-conversion from ice crystal to grauple and then grows through collecting ice crystals. AgI-seeding should be done before the activation of most ice nuclei start, so as to enhance rainfall through increasing ice crystals content, and deleting super-cooled cloud water. Otherwise, there will be large amount ice crystals grew in natural clouds, artificial nuclei would be useless.