关键词: 湿位涡, 西南涡, 暴雨, 涡度收支

Abstract:

Based on the NCEP reanalysis data with 1° × 1° spatial resolution，the conventional observation data，the precipitation from the automatic weather stations and the TBB with 0．1° × 0．1° spatial resolution from FY－2E satellite，a heavy rainfall process occurred in eastern Sichuan from 29 June to 1 July，2013 was analyzed，firstly．And then the structure of southwest vortex causing the heavy rainfall was investigated emphatically by using the vorticity budget equation．The results indicated that the horizontal convergence and divergence term as well as horizontal advection term played a direct role in the development of southwest vortex．The horizontal convergence and divergence term was the main contribution to the vortex development before the vortex formed，while the influence of the horizontal advection term increased after its formation，and was mainly positive contribution in the middle and lower troposphere．The influence of the twist term on the vortex development was smallest．The vertical transport term was mainly consisted of positive valucs in earlier stage of the vortex formation while in weakening stage of the vortex it was negative contribution．In earlier stage of the southwest vortex formation，the potential vorticity from the high level troposphere was transported downwards to the middle level troposphere，and led to the development of the low level vortex．

Key words: southwest vortex, heavy rainfall, vorticity budget, moist potential vorticity