云南冬季一次强降水天气过程的模拟与分析  

Numerical Simulation and Analysis on a Severe Precipitation Proceses over Yunnan in Winter

作　　者：许美玲[1] 段旭[2] 

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》2007年第2期414-421,共8页Plateau Meteorology

基　　金：云南省科技攻关及高新技术计划项目(2006GS25)资助

摘　　要：利用MM5中尺度非静力模式对2003年1月5～6日发生在云南省的强降水天气过程进行了数值模拟分析。结果表明：（1）偏南低空急流是造成冬季暴雨的主要影响系统，低空急流上的扰动导致一个相对大的风速核从急流主体分裂东移，风速显著加大，风向呈气旋性弯曲，引起低层涡度增加，产生强的辐合上升运动。（2）低空急流的形成和移动与中层南支槽的关系较为密切，南支槽前的辐散为低空急流的形成提供了启动机制。（3）强降水天气出现在冷暖空气交汇的区域，锋生强迫作为暖湿气流上升的强迫机制之一，对强降水的形成起着不可忽视的作用。（4）水汽条件的分析表明，暴雨区的水汽主要由低层水汽辐合来提供。The severe precipitation process occurred over Yunnan at 08：00 from 5 to 6 January 2003 was simulated using the mesoscale numerical model MM5. The results of analysis indicate that the southwest lower-level jet（LLJ） is the main synoptic system which resulted in the heavy rain. Disturbance of the LLJ bring on increasing of vorticity at lower layer and enhancement of rising motion. The formation and motion of the LLJ is closely related with the southern branch westerly trough on middle level, the divergence in front of southern branch westerly trough provide major start-up mechanism for forming the LLJ. The heavy rain occurred in the region where the cold and warm are met. Frontogenesis is one of forced mechanisms of warm air lifting, which play very important role in the heavy rain occurring. Water vapour mainly comes from its convergence at lower layer in region of heavy rain.

关 键 词：MM5模式 冬季强降水 低空急流 南支槽 

分 类 号：P426.6[天文地球—大气科学及气象学]