1998年二度梅雨锋的演变及结构特征

应用气象常规资料对1998-07-21-24日暴雨时段的二度梅雨锋的演变和其不同阶段的水平、垂直结构进行了诊断分析,确认了二度梅雨锋结构的一些普遍特征,如在对流层低层表现为θe锋而不是温度的强烈对比;同时揭示了1998-07的二度梅雨锋结构不同于一般梅雨锋的典型特征:700 hPa以下的梅雨锋向南倾斜或近乎垂直,切变线位于梅雨锋南侧,梅雨锋具有相当正压性.结果还表明:1998年二度梅雨锋结构不同于温带锋面结构,而是更倾向于赤道辐合带的性质,并且在各个阶段其结构并不完全相同.

Evolution and Structures of Meiyu-Front during the Secondary Meiyu-Season in 1998

The evolution and structures of Meiyu front resulting in rainstorm during the secondary Meiyu season in 21 24 July 1998 are analyzed based on the meteorological conventional data, four evolving stages are found, and some common characteristics are also confirmed, for example, potential temperature contrast is stronger than temperature contrast in low level of troposphere. It is found that some characteristics of secondary Meiyu front in July 1998 is different from ordinary Meiyu front, which include that Meiyu front below 700?hPa slopes southwardly, sometimes it is vertical approximately; the shear line lies in southern of Meiyu front; the front has equivalent barotropic characteristic. The results also show that the secondary Meiyu front in 1998 is different from temperate front, but it is inclined to ITCZ, furthmore, it isn't alike completely in each stage.