Abstract:

Based on the theory of isentropic potential vorticity(IPV)，a diagnostic analysis of a continuous rain process in the east of Northwest China in the second ten—day of May in 2005 WaS carried out．The results show that the large circulation background which influenced this continuous rain process was the h Jigh ridge near the Ural Mountain and the continually deepening trough near the Balkhash Lake；this continuous rain process Was caused by the low vortex continually created from the plateau together with the cold air split from the north．Because of the topographic effect of the Tibetan Plateau，the hi sh potential vorticity O11 the isentropic surface was transported to the lower reaches along the north side of the plateau；the high value area of IPV Was closely associated with the precipitation area。and the positive value area of IPV Can reflect the movement of the cold air，thus it Call be a significant predictor．

Key words: continuous rain, isentropic potential vorticity, the east of Northwest China

摘要：

应用等熵位涡原理，对2005年5月中旬西北地区东部的一次连阴雨过程进行了诊断分析。结果表明：影响这次连阴雨过程的大环流背景是乌拉尔山附近存在一高压脊，同时在巴尔喀什湖附近在一不断加深的槽；这次连阴雨过程是由高原不断生成的低涡与北边分裂下来的冷空气所共同造成的；由于青藏高原大地形的作用，等熵面上高位涡沿高原北侧向下游输送；等熵位涡高值区与降水区有较好的对应关系，IPV正值区能够反应冷空气的移动，具有较好的预报指示意义。

关键词: 连阴雨, 等熵位涡, 西北地区东部