中文摘要：

利用加入碘化银冷云催化模块的中尺度数值模式WRF对2014年5月9-11日发生在华北地区的一次降雨天气过程进行了增雨催化数值模拟研究。模式的催化参数根据实际增雨作业信息进行设置,探讨了增雨的效果和机理,并针对催化高度和催化剂量进行了两组敏感性试验。结果表明：在高度5-6 km,温度-20--15℃左右的冷云区位置引入碘化银冷云催化剂可使地面降水量显著增加。地面增雨开始于作业后30 min左右,70 min左右达到最大,90 min后出现减雨,110 min后减雨效果大于增雨。增雨机制主要为：碘化银的播撤使融化层之上云中的过冷水含量显著减少,冰雪晶的含量增加,雨滴碰并雪的过程和雨滴捕获云滴的过程增强;增加的雪晶下落到暖区融化成雨滴的过程增多,最终造成地面降雨量的显著增加。从微物理过程的量级来看,雪晶粒子的融化是导致降水增加的最主要过程。不同催化高度和催化剂量的敏感性试验结果表明,针对这次过程在过冷云水丰富,温度较低而冰雪晶含量相对较少的高度进行催化效果较好。继续加大催化剂量,可以起到更好的增雨效果。

英文摘要：

Nnumerical simulation research on silver iodide（AgI） cold cloud seeding is conducted,focusing on the precipitation process that happened in North China from 9 to 11 May 2014.The WRF model coupled with silver iodide cold cloud catalytic module is used and the model parameter settings are based on actual artificial precipitation operations.The effect and mechanism of the precipitation are discussed and then two sensitivity tests on operation height and catalyst content are carried out.The results show that seeding appropriate catalyst content of AgI at about 5-6 km height and temperature of-20—15℃ can make ground precipitation increased significantly.Ground rain enhancement begins at about 30 minutes after seeding operation,and 70 minutes to reach the maximum,while rain reduction occurs after 90 minutes,and 110 minutes later the reduction of rain is more than the increase of rain.The main mechanism for precipitation is as follows.The AgI seeding makes the cold water content above the melting layer in cloud remarkably reduced,snow and ice content increased,and coalescence processes of rain and snow and rain capture cloud droplets enhanced.Increased snow crystals fall into the warm zone and melt into raindrops,then the rainfall significantly increases.Regarding the magnitude of microphysical processes,the snow particles’ melting is the main process leading to increased precipitation.Results of the two sensitivity tests show that the catalytic effects are better when seeding in clouds with rich super-cooled cloud water,low temperature and low ice crystal content,and increasing the amount of catalyst could have better seeding result.