AgI焰剂对层状云催化的数值模拟研究  

Simulation of AgI Seeding on Stratiform Cloud with Category Model

作　　者：杨洁帆[1,2] 雷恒池[1] 

机构地区：[1]中国科学院大气物理研究所云降水物理与强风暴试验室,北京100029 [2]中国科学院研究生院,北京100049

出　　处：《气候与环境研究》2010年第6期705-717,共13页Climatic and Environmental Research

基　　金：国家自然科学基金资助项目40537043和40775007;国家科技支撑项目2006BAC12B001-01-06

摘　　要：使用包含详细微物理过程的一维层状云全分档模式,并加入AgI焰剂催化方案,对2007年吉林省长春市一次层状云降水过程进行AgI播撒试验。分别选取云内过冷水含量峰值区(4000m)、最大冰面过饱和度区(5000m)和低温度区(5500m)作为播撒试验区,播撒时间选择云体未充分发展阶段和充分发展阶段。结果显示,在同等播撒剂量下,地面降水对云内AgI播撒高度较为敏感。ST2方案模拟400min后地面累计降水量增加10.4%。同等条件下,播撒时间越早,催化效果越佳。在充分发展的云体内播撒AgI焰剂,40min后云内过冷水含水量减少70%以上,表明云内过冷水消耗量与地面雨强增加量之间具有良好的正相关性。4种播撒方案均显示,云内AgI主要靠凝华核化机制产生冰晶,而接触核化机制对AgI核化过程贡献较小。与未催化云体相比,催化后云内冰晶粒子总凝华速率增加明显。同时,地面雨强增加,最大雷达回波强度减小。地面水滴粒子谱分布显示,相比于未播撒时,各播撒方案均使直径400μm左右的水滴粒子浓度增加1个数量级以上,而水滴粒子谱宽均略有下降,这表明AgI播撒后主要通过增加可降水粒子数量来影响地面降水强度和累计雨量,而对降水粒子谱型拓宽的贡献有限。A 1-D category model including detailed microphysical processes and AgI seeding schedule has been used to investigate the possible effects of AgI seeding on precipitation and microphysical processes of stratiform cloud on 1 Jun 2007 in Jilin Province,China. The altitudes with the maximum supercooling water content （4000 m）,the maximum supersaturation with respect to ice （5000 m） and low temperature （5500 m） within cloud have been selected as the seeding areas. The two phases when the precipitation is developing and when it has sufficiently developed have been set as the seeding time. It is indicated that with the same mass of AgI seeded in the cloud,the ground rainfall intensity is sensitive to the seeding altitude. After 400 min simulation with ST2 seeding scheme,there is a 10.4% increase in accumulative rainfall compared with the unseeded cloud. Under the same circumstance,the earlier the seeding is,the more prominent the effect will be. The modeling results show that 40 min after the sufficiently developed cloud being seeded with AgI more than 70% supercooled water within cloud is consumed unveils a negative correlation between the depletion of supercooling water intensity. The main mechanism of AgI nucleation is sublimation,and contact nuclei contribute little to AgI nucleation. In comparison with unseeded cloud,there is a considerable increase in the sublimation rate of ice crystal. Meanwhile,the maximum radar echo decreases as rainfall intensity increases. The rain droplet spectra show that the spectrum width decreases despite the fact that the four seeding schemes can all bring a 10-times-increase in number concentration of rain droplet,which reveals that accumulative precipitation is affected by the increasing of number concentration of rain droplet rather than the wilding of spectrum.

关 键 词：分档模式 AgI播撒 粒子谱型 层状云 

分 类 号：P467[天文地球—大气科学及气象学]