2012—2020年西南低涡气候特征及对重庆暴雨的影响

Climatic Characteristics of Southwest China Vortex and Its Impact on Rainstorm in Chongqing from 2012 to 2020

基于2012—2020年西南低涡年鉴资料,统计分析了西南低涡的时空演变及涡源、移动路径、生命史等气候特征,再结合雨量数据分析了西南低涡对重庆暴雨的影响。结果表明:(1)西南低涡一年四季都有生成,其中3—6月频发,尤其是在6月最多,7月和8月最少;白天和夜间生成几率大致相当,但盆地涡主要在夜间生成,而小金涡以白天生成为主。(2)西南低涡中,九龙涡最多,盆地涡次之,小金涡最少;大部分西南低涡生成后会在源地消亡,其中小金涡更易移出生成地,盆地涡较九龙涡和小金涡的移出率低。(3)西南低涡移动总体上可分为东北、正东、东南和西南共4个方向,以偏东方向移动为主,最远可达我国东北和华东地区。(4)超过80%西南低涡的生命史小于48 h,个别生命史长达120 h以上,最长可达180 h。(5)76%的重庆区域性暴雨与西南低涡有关,主要以盆地涡影响为主,其对长江以北的重庆各区县影响尤为明显。

By using the Southwest China Vortex Yearbook from 2012 to 2020,the temporal and spatial variation characteristics of Southwest China Vortex(SWCV)and the climatic characteristics such as vortex source,moving path and life history are statistically analyzed.Combined with the rainfall data of Chongqing,the impact of SWCV on rainstorm in Chongqing is analyzed.The results show that:(1)The SWCV is generated all year round with obvious annual,seasonal and monthly differences.It occurs the most from March to June,especially in June,and the least in July and August.The probability of generation in daytime and night is roughly the same,but the Sichuan Basin Vortex is mainly generated at night,while the Xiaojin Vortex is mainly generated during the day.(2)The Jiulong Vortex is the most in the SWCV,followed by the Sichuan Basin Vortex,and the Xiaojin Vortex is the least.Most of the SWCV will die out in the source after being generated.Among them,the Xiaojin Vortex is easier to move out of the generating area,and the removal rate of the Sichuan Basin Vortex is lower than that of the Jiulong Vortex and the Xiaojin Vortex.(3)The SWCV moves in four directions:northeast,east,southeast and southwest,mainly in the east direction,up to the northeast and East China.(4)More than 80%of the SWCV lasts less than 48 hours.With the increase of time,the maintenance frequency of the SWCV decreases significantly.The life history of individual SWCV can be more than 120 hours,up to 180 hours.(5)76%of the regional rainstorms in Chongqing are related to the SWCV.The Sichuan Basin Vortex is the main cause of the regional rainstorm in Chongqing,especially in the districts and counties north of the Yangtze River in Chongqing.