中文摘要：

利用15年（1990年-2004年）的逐日天气图资料对西南低涡的产生和移动情况进行了统计分析．结果表明低涡的发生频次具有明显的季节变化，15年共统计出1038次西南低涡，其中生命史维持1d以上的西南低涡共有262次，春、夏两季出现的频数比较多，其中春季一共发生77次占29．4％，夏季一共发生92次占35．1％；而秋、冬两季比较少，秋季一共发生55例占21．0％，冬季一共发生38例占14．5％．西南低涡存在两个主要的生成区，高原东南缘生成区和四川盆地生成区，其中，高原东南缘生成区是最主要的生成区．大多数西南低涡的维持时间较短，生命史在1d以内的共776例占74．8％，生命史在1～3d之间的有239例占23．0％，生命史在3～6d之间的有21例占2．0％，只有2例生命史达到6～7d．移动性低涡占西南低涡总数的极少部分，15年仅统计出60例，约占全部西南低涡总数的6％，其中，按移动情况大致可分为四种，分别为东北路径（占移动类低涡的33．3％）、偏东路径（占移动类低涡的50．0％）、东南路径（占移动类低涡的5．0％）和少动路径（占移动类低涡的11．7％）．西南低涡的强度分布从南至北明显递增，在东西方向上也略有变化，为先增强再减弱．从南往北移动有利于西南低涡的维持和发展，从东往西移动，西南低涡将先有所增强，然后再有所减弱．

英文摘要：

In this paper, the characteristics of the southwest vortexes are statistically studied using the daily weather map data from 1990 to 2004. The main results are shown： （1） The frequency of the southwest vortexes change greatly at different seasons, there are total 262 vortexes whose lives sustain more than one day, and it is of high frequency in spring and summer, respectively with 77 vortexes （29.4% of the total） and 92 vortexes （35.1% of the total）. The frequency is lower in autumn and winter, and the vortexes are 55 （21.0% of the total） and 38 （14.5% of the total）, respectively. （2） There are two main regions for the generation of the southwest vortex. One is along the southeast edge of the Tibet Platean and the other is in the Sichuan Basin, and the former is the most important region, when compared with the latter. （3） The lifecycle of most vortexes is shorter than one day, whose number is about 776 and is 74.8% of the total. About 239 vortexes （23.0% of the total） could sustain 1 to 3 days, 21 （2.0% of the total） can sustain 3 to 6 days, only 2 could undergo 6 to 7 days. （4） Only 6% of the total southwest vortexes can move out of their generation regions, and the moving tracks can be roughly classified into four kinds, the northeast track （33.3% of the total moving vortexes）, the eastward track （50.0% of the total moving vortexes）, the southeast track （5.0% of the total moving vortexes） and the quasi-stationary track（11.7 of the total moving vortexes）, respectively. （5） The intensity distribution of the southwest vortexes increases obviously from the south to the north, while changes slightly from the west to the east, strengthening first and then weakening appreciably.