两次高原涡与西南涡作用下的暴雨过程对比分析

利用FY-2D卫星TBB资料、NCEP1°×1°再分析资料和地面自动站观测资料,对2008年7月20~22日和2012年7月20~22日两次由高原涡和西南涡相互作用,造成四川暴雨过程进行对比分析,结果表明:(1)强降雨落区与引导高原涡移动的高空槽有密切关系,高空槽的移动和变化大致决定了强降雨的落区。(2)造成两次暴雨过程的对流云团生成和发展虽然有一定的差异,但最终会发展合并形成一个MCC;并且强降雨位于对流云团TBB最大梯度区,一般靠近亮云核,并在亮云核的西北部。(3)两次暴雨过程期间,均有低层辐合高层辐散,对应着强的涡度和强的上升运动,并且散度、涡度和垂直速度都是增大的。(4)两次暴雨过程期间水汽来源存在着差异,但水汽是逐渐增强的,并且水汽辐合中心与强降雨落区相对应。

Comparative Analysis of Two Heavy Rainfall Processes under Interaction of Plateau Vortex and Southwest Vortex

Using FY-2D satellite data, NCEP 1° × 1° reanalysis data and surface observation data, two torrential rain processes, form 20th to 22nd July, 2008 and 20th to 22nd July, 2012 in Sichuan caused by the interaction between plateau vortex and southwest vortex have been compared and analyzed. The results show： 1 ） the heavy rainfall area and the upper trough which guides the plateau vortex to move have close relationship, the migration and variation of upper trough decides the general area of the heavy rainfall. 2） Although the generation and development of convective clusters which cause the two tor- rential rain processes have some differences, but in the end will be combined to form a MCC, the heavy rainfall locates on the TBB maximum gradient area of convective cluster, and usually closes to the cloud core, in the Northwest of the cloud core. 3） Two torrential rain processes both have the low -level convergence and high -level divergence, and correspond to the？ strong vortieity and？ strong ascending motion, and the divergence, vorticity and vertical velocity？ both increase. 4） The vapor source of the two torrential rain processes has some differences, but the vapor both gradually enhances, and water vapor convergence center corresponds to the area of heavy rainfall.