干旱地区一次低涡中心对流暴雨山洪过程分析及ROSE评估

Analysis of Convective Rainstorm Mountain Torrent Process and ROSE Evaluation in an Arid Area

综合使用常规Micaps资料、临河雷达ROSE资料等,对2023年7月20日巴彦淖尔市对流暴雨过程进行了分析,重点讨论了过程发生的中尺度环境条件时空演变特征及暴雨成因。结果表明:1) 4号台风“泰利”从北部湾将水汽向北输送至巴市次级水汽源地四川,西风槽将水汽继续向北输送至河套地区,为此次过程提供了充分的水汽。2) 低涡中心沿阴山山脉南侧缓慢东移致使此次强降水时间延长。3) 阴山南侧摩擦层局地南风超低空急流维持使低层暖强迫加强形成列车效应,致使后旗局地形成短时暴雨。4) 阴山、乌拉山的地形作用加剧了强对流的发展。5) ROSE评估分析,降水估测随着距离增大准确率逐渐降低,短时强降水报警虽然受冰雹影响较大,但对山洪风险预警发布有一定指导意义。

The process of convective rainstorm in Bayan Nur City on July 20, 2023 was analyzed by using conventional Micaps data, Linhe radar ROSE data, etc. and the spatio-temporal evolution characteristics of mesoscale environmental conditions and the cause of rainstorm were discussed. The results show that: 1) Typhoon No. 4 “Tali” transported water vapor northward from Beibu Gulf to Sichuan, the secondary water vapor source of Ba City, and the westerly trough continued to transport water vapor northward to Hetao area, providing sufficient water vapor for this process. 2) The slow eastward movement of the center of the vortex along the southern side of the Yinshan Mountains resulted in the prolonged duration of the heavy rainfall. 3) The maintenance of ultra-low level jet in the south friction layer of Yinshan strengthened the low level warm force and formed a train effect, resulting in the formation of short-term rainstorm in the rear area. 4) The topographic effects of Yinshan and Wulashan intensified the development of strong convection. 5) ROSE assessment and analysis showed that the accuracy of precipitation estimation gradually decreased with the increase of distance. Although short-term heavy precipitation warning was greatly affected by hail, it had certain guiding significance for flash flood risk warning.