Abstract:

Based on the hourly precipitation of automatic weather stations and NCEP reanalysis data, the vorticity budget and latent heat release of the heavy rainfall with southwest vortex occurring in Chongqing on 8 to 10 July 2010 were diagnosed and analyzed. Results are as follows: (1) the coupling of the center of regenerating southwest vortex on 850 hPa with sustaining southwest vortex on 700 hPa triggered the occurrence and development of the heavy rainfall. (2) During the heavy rainfall, the vertical transport and horizontal convergence and divergence terms of vorticity played a dominant role in the regeneration and development of low vortex on 850 hPa and the sustainable development of low vortex on 700 hPa. (3) The precipitation basically synchronized with the low vortex. The latent heat that caused by precipitation constantly strengthened the upward movement near the centre of convection, then latent heat release increased, which caused PV enhancement, and the positive vorticity near the vortex centre enlarged, which led to significant cyclonic bend of wind field , then the low vortex circulation gradually formed.

Key words: southwest vortex, low-level jet, vorticity budget, latent heat

摘要：

利用NCEP/NCAR再分析资料、地面自动站降水资料，对2010年7月8～10日发生在重庆地区的大暴雨过程进行涡度收支及潜热释放诊断分析。结果表明：（1）再次发展的850 hPa西南低涡中心与持续发展的700 hPa低涡中心的耦合发展对此次暴雨过程的发生发展有重要作用；（2）在暴雨过程中，涡度的垂直输送项和水平辐合辐散项对850 hPa低涡的再次发展及700 hPa低涡的维持发展起主要作用；（3）降水与低涡基本同步发生，降水带来的潜热释放使得对流中心附近的上升运动不断加强，凝结潜热释放也随之增多，引起非绝热作用增强，导致局地位涡增加和低涡中心附近的正涡度逐渐加大，风场气旋性弯曲显著，低涡环流逐渐形成。

关键词: 西南低涡, 低空急流, 涡度收支, 潜热加热