2009~2019年大渡河上游暴雨的时空分布和环流特征分析

Spatial-Temporal Distribution and General Circulation of Rainstorm over the Upper Reaches of Dadu River in 2009-2019

利用2009~2019年大渡河上游降水资料和NCAR/NCEP(1°×1°)再分析资料对大渡河上游的暴雨进行综合分析,结果表明:2009~2019年大渡河上游共发生了28次暴雨过程,2014年最多;发生季节主要集中在6~9月,以6月最多,占总次数的28.6%;强降水时段集中在20时~02时,具有明显的日变化;暴雨的发生频次呈现中间多,南北少的特征,中心位于马尔康。根据暴雨的影响系统不同,可分为3类:高空槽型、高原切变线型和高原低涡型,所占比例分别为46.4%、35.7%和17.9%;高空槽型在9月最多,高原切变线型在7月最多,高原低涡型在6月最多。同时选取3个历史个例分析了不同类型暴雨的环流特征。

Based on rainfall data and the NCAR/NCEP 1°×1° reanalysis data over the upper reaches of Dadu River from 2009 to 2019,composite analyses of rainstorm over the Upper Reaches of Dadu River was carried out.The results show that:There were 28 cases of rainstorm over the upper reaches of Dadu River from 2009 to 2019,and most times in 2014.The occurrence seasons were mainly in June to September,with the most in June,accounting for 28.6% of the total times.The heavy rainfall concentrated from 20:00 p.m. to 2:00 a.m.,with obvious diurnal variation.The frequency of rainstorm was more in the middle and less in the north and south,and the center was located in Barkam.Based on the different influencing system of the rainstorms,they could be divided into three types,which were high trough type,plateau shear line type and plateau vortex type,accounting for 46.4%,35.7% and 17.9% respectively.The high trough type was the most in September,the plateau shear line was the most in July,and the plateau vortex type was the most in June.The circulation characteristics of different types of rainstorm were analyzed for three historical cases.