盆地西南部一次强降雨过程风场特征分析

Analysis of Wind Field Characteristics during a Heavy Rainfall in the Southwestern Basin

  • 摘要: 利用地面观测资料、风廓线雷达资料和ERA5再分析资料,对2024年7月24日四川盆地西南部一次强降雨天气过程的风场特征进行分析。结果表明:(1)850 hPa以下的东北气流在盆地西南部形成地形抬升运动,有利于产生强降雨;(2)地面辐合线的形成是地形与对应层次高空风共同作用的结果,西北风主导时在沿山地带形成多条阶梯型短辐合线,东北风主导时形成西北-东南向长辐合线;(3)组网雷达反演的风场能反映对流系统由低到高且自东向西倾斜的特征,在2.5°层有小尺度多涡旋结构;(4)风廓线雷达能较好地捕捉高空风的演变特征,其垂直速度跟雨强大小呈反比。

     

    Abstract: On July 24, 2024, a heavy rainfall weather process occurred in the southwestern Sichuan Basin, the wind field characteristics of the process were analyzed by using ground observation data, ERA5 reanalysis data and wind profile radar measurements. The results showed that: (1) The northeast airflow below 850 hPa induced a topographic uplift over the southwestern Basin and produced the heavy rainfall. (2) The surface convergence line was formed by the joint influence of topography and the corresponding level of high-altitude winds, and the northwest-southeast long convergence line was formed when the northwest wind was dominant, and the northwest-southeast long convergence line was formed when the northeast wind dominated. (3) The network-retrieved radar wind fields revealed that the convective system exhibited an east-to-west tilted structure from low to high levels, with small-scale multi-vortex features observed at the 2.5° elevation layer. (4) The wind profile radar showed the evolution of the upper-air wind well, and its vertical velocity was inversely proportional to the strength of the rain.

     

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