低纬高原地区一次罕见大暴雨的中尺度数值模拟  

Study on Mesoscale Numerical Simulation of a Heavy Rain Strom over Lower Latitude Plateau of China

作　　者：许美玲[1] 段旭[2] 张腾飞[1] 杨明珠[1] 

机构地区：[1]云南省气象台,云南昆明650034 [2]云南省气象科学研究所,云南昆明650034

出　　处：《高原气象》2006年第2期268-276,共9页Plateau Meteorology

基　　金：中国气象局新技术推广项目(CMAT2005M39)资助

摘　　要：利用MM5V3中尺度数值模式，对2003年6月16日20：00～17日08：00云南楚雄等地大暴雨的中-β尺度系统的发生、发展进行了数值模拟。模拟结果表明：强降水中心与实况基本吻合，但模拟降水量比实况偏弱；中-β尺度系统发展的初期低层质量辐合先于高层辐散增强，而减弱阶段也是低层辐合减弱先于高层辐散减弱，也就是说低层散度场的变化引起高层的变化；中-β尺度系统的发展、增强、减弱过程，主要靠低层的正涡度制造；低纬度地区水汽分布差异较高纬度地区小，水汽的辐合主要取决于风场辐合，而平流输送则决定暴雨的持续时间；高原地形对空气的上升运动和水汽辐合有一定影响，特别是在背风坡，上升运动均有所减弱，水汽呈弱的辐散。The mesoscale numerical model MM5V3 was used to simulate the occurrence and development of meso-β scale systems which resulted in the heavy rain strom at Chuxiong and some other stations of Yunnan from 20：00 on 16 to 08.00 on 17 June 2003. The result indicate that the simulated center of rain strom is basic similar with the real rainfall, but the simulated rainfall intensity is less than that real. The mass convergence at lower layer enhance in advance of divergence at upper layer in initial state of development of meso-β scale, and the convergence at lower layer weaken in advance of divergence at upper layer in weak state, that is the change of divergence filed at lower layer induce that at upper layer. The development, intensification and attenuation of meso-β scale systems mainly are caused by positive vorticity at lower layer. The discrepancy of water vapour distribution at lower latitude is smaller than that high latitude, water vapour convergence result mainly from wind filed convergence, and advection transportation decided durative time of rain strom. The plateau＇s orography has some influence upon ascending motion and water vapour convergence in the atmosphere, especially in its lee slope, rising motion will weaken.water vapour appear weak divergence.

关 键 词：中-β尺度系统 数值模拟 大暴雨 低纬高原 

分 类 号：P458.121.1[天文地球—大气科学及气象学]