摘要
在对华南2004年3月31日～4月1日的冷锋降水天气过程进行正确模拟的基础上,通过向云中引入人工冰晶研究了催化效应,结果表明：催化使地面雨量在催化后30 min开始增加,80 min时达到峰值,120 min时减小到最小值。被催化的云团随着自然雨带逐渐向东南方向移动,并且催化云影响其周围的云团,造成了催化的下风方域外效应,使催化效果可以延长到催化后10个小时,随着自然云的消散而结束。人工冰晶的引入,使得大量过冷雨滴快速转变为霰粒,霰粒通过淞附云水和碰并雨滴过程增长,使降水提前发展,之后霰粒的融化使地面雨量增加。大量冻结潜热的释放,使云中温度增加,上升速度增强,说明“静力催化作用”和“动力催化作用”是相互关联不可割裂的。在云体发展早期冷云降水过程还没有启动之前引入人工冰晶的催化效果优于云体发展接近成熟时的催化效果,而只由催化剂量的不同造成的增雨差异较小。
Based on the reasonable simulation of cold frontal precipitation event in South China on 31 March 2004, seeding effects through directly adding ice crystals in the simulated clouds are studied. The results show that after seeding 30 minutes surface rainfall started to increase, after seeding 80 minutes the Net Rainfall Increment （NRI） reached a peak, then after 120 minutes NRI decreased to a minimum. The seeded cloud moved southeasterly with the natural precipitating band moving, and the seeded cloud influenced the neighboring clouds, which caused the seeding effects last about 10 hours, then dissipated with the natural clouds dissipating. The seeding effects conformed to the hypothesis of ＂downwind extra-area effects＂. Supercooled raindrops were quickly transferred into graupels after artificial ice crystals were injected. Then graupels grew mainly through riming supercooled cloud water and collecting raindrops. Thus precipitation developed in advance, then the melting of graupels caused the surface rainfall increase. The release of a large quantity of fusion latent heat made the temperature in cloud increase,strengthened the updrafts, which indicated that ＂static seeding＂ and ＂dynamic seeding＂ are correlative each other. The seeding effects of adding ice crystals in the cloud developing stage were better than those in the cloud mature stage. The difference of NRI caused only by the seeding agent dose in different seeding experiments was relatively small.
出处
《大气科学》
CSCD
北大核心
2008年第6期1256-1275,共20页
Chinese Journal of Atmospheric Sciences
基金
国家自然科学基金资助项目40705002
40305001
社会公益研究专项2004DIB3J116
国家科技支撑计划2006BAC12B01
国家重点基础研究发展规划项目2004CB418306
广东省科技计划项目2003C32607
关键词
冷锋降水
人工引晶
催化试验
中尺度数值模式
cold frontal precipitation, artificial ice crystals, seeding experiment, mesoscale numerical model
