利用0.5°×0.5°分辨率的CFS再分析资料，对2004—2017年5—10月西南涡进行了普查，按TMPA V7资料显示的降水分布特征对西南涡进行分类。统计了不同类型西南涡出现的频数，并对西南涡降水特征进行分析，包括降水范围与强度等，最后分析了4类西南涡代表个例的环流和降水形成机制差异。结果表明，夏半年西南涡降水依次频繁出现在西南涡东北部、东部、东南部、中部；分析4类频数较多的西南涡降水特征，发现中部降水型暴雨范围最广，降水强度最强，其次为东南降水型、东部降水型与东北降水型。对代表个例的环流特征分析发现，中部降水型西南涡与东北型冷暖气流均在盆地北部相遇，不同的是，中部降水型冷空气范围更大，并与西南气流形成环型流场；东南降水型与东部型相似，二者均无冷空气入侵，差异表现在东部降水型西南气流偏东，并翻越大巴山，而东南降水型气流遇大巴山后向西绕流。对各类西南涡降水形成机制的分析，发现西南涡降水与其临近地区显著的垂直环流圈有密切关系，降水区通常与环流圈位置对应。

Based on the CFS reanalysis data with spatial resolution of 0.5×0.5 degrees, we conduct a census of the Southwest Vortex from May to October in 2004—2017 after making a quality test to CFS and TMPA V7 data. According to the precipitation distribution shown by TMPA V7 data, we classified Southwest Vortex. The frequency of the precipitation in different directions is counted, and the precipitation characteristics of the four most types are analyzed, including the range of rainstorm and the intensity of precipitation. The circulation differences as well as precipitation formation mechanism of the four representative cases are analyzed. The results show that, there is a consistently growth in the amount of Southwest Vortex through these summer half years. Moreover, the southwest vortex precipitation frequently occurred in the northeast, east, southeast and central parts of the southwest vortex successively in the summer half year. Analysis of four kinds of frequent frequency southwest vortex precipitation characteristics. It is found that precipitation in central section has the largest average range of rainstorm and the strongest precipitation intensity, followed by precipitation in southeast part of southwest vortex, east part and northeast part successively. Through the analysis of circulation situation on representative case, we found that, both in the type of central part and northeast part precipitation, cold and warm currents meet in the northern part of the basin. The difference is that central part precipitation occurs when there is a wider range of cold air intrusion at the low level and the southwest airflow is stronger compared with the type of northeast part precipitation. These two branches form a circular flow field in the basin which is different from confrontation state happened in the type of northeast part precipitation. The type of east and southeast part precipitation happens when there is no cold air invasion. The last one happens when the southwest current turn westward in front of Daba Mountains. However, the former one happens when the current flows eastward compared with type of southeast part precipitation and finally flows across Daba Mountains. The formation mechanism of four kinds of Southwest Vortex is analyzed. It is found that there is a significant vertical circulation in Southwest Vortex. The circulation circle is usually composed of an ascending airflow near the southwest vortex and a downdraft of the north side. The precipitation area is usually corresponding to the position of the circulation circle.