2003年7月4～7日淮河流域特大暴雨等熵位涡分析

Isentropic Potential Vorticity Analysis of Heavy Rain in the Huaihe River Valley during 4-7 July 2003

利用等熵位涡理论对 2 0 0 3年江淮梅雨期 7月 4～ 7日淮河流域特大暴雨进行了天气动力诊断分析。发现 :等熵面上的西风急流将高位涡向下游输送 ,强西北气流穿越等压线形成强下沉气流 ,将高层和高纬的高等熵位涡向南输送 ,使得强降雨区维持高等熵位涡 ,是强雨带持续的重要原因。等熵位涡高值区与强暴雨有较好的对应关系 。

A synoptic dynamic diagnosis of the heavy rain event in the Huaihe River valley from 4 to 7 July 2003 is carried out with the theory of isentropic potential vorticity (IPV). The results show that the westerly jet on the isentropic surface transported the high potential vorticity to the lower reaches, while the strong NW flow traversing the isobars became a strong sinking flow and transported the high IPV southward from higher layers and higher latitudes. This process kept a high IPV above the rain area and thus counted for the persistency of the heavy rain band. High IPV area is closely associated with heavy rain and thus can be a significant predictor.