低涡和副热带高压共同影响下的暴雨落区分析

Analysis of the Common Effect of Vortex and Subtropical High on Rainstorm Fall Area

应用常规观测资料和NCEP 1°×1°再分析资料,分析低涡和副热带高压共同影响下的暴雨过程,发现暴雨落区并不与低涡位置及路径一致,因而不能简单的按其位置和路径预报暴雨落区,应着眼于暴雨发生的物理机理,注意分析影响系统的空间结构、发展阶段和地面形势的演变特征。在有锋面系统影响时,初始对流往往由锋面触发,因此,暴雨的第一落区在锋面附近。冷锋触发的暖区暴雨随后出现,不需强的动力辐合条件,可能远离低涡中心,而是位于副热带高压边缘的高温湿舌内。另外,应密切关注周边初生的对流云团及其移人时造成的暴雨。

By using conventional observation data and NCEP 1°×1° reanalysis data,analysis on the common effect of vortex and subtropical high on rainstorm process is done.It is found that the heavy rainstorm fall area is not consistent with the vortex location and path.So,it is not always reasonable to forecast the rainstorm fall area following the location and path of vortexes.Forecasters should do some analysies on the spatial structurs of impact systems,the developing stages and the evolution characteristics of surface situation.When the impact system is frontal system,the initial convection system is often trigger by the frontal surface.Therefore,the fisrt rainstorm fall area tends to appear near the frontal suface,and then heavy rain in warm zone triggered by the cold front follows,not needing the strong dynamic convergence conditions.The heavy rains may fall far away from the vortex center,but is located in the high temperature and wet tongue on the edge of subtropical high.In addition,more attentions should be paid to the primary convective clouds on the surroundings and the heavy rain brought by the convective clouds.