川西高原两次致雨高原涡特征分析

Characteristic Analysis of Two Rain-producing Plateau Vortex Events over the Western Sichuan Plateau

  • 摘要: 利用ERA5再分析资料,结合地面资料、卫星云图、雷达产品,对2024年7月22—26日两次高原涡移动特征进行分析。结果表明:两次低涡整体呈浅薄趋势,均位于高压脊线附近的散度区中;发展初期与400 hPa假相当位温高值区有关,发展维持时和热对流及中高层强上升气流有关系;高原涡旋云系东移南压进入川西高原,并得到持续发展,是带来强降水的主要系统;两次高原涡以大面积层云回波为主,移动缓慢,降水回波基本保持静止,强回波中心均在垂直方向上产生了回波墙,在局地产生较强降水。

     

    Abstract: Using ERA5 reanalysis data, combined with ground data, satellite cloud imagery and radar products, the characteristics of two plateau vorticity movements during July 22—26, 2024 were analyzed. The results show that the two vortices exhibited generally shallow structures and were located within divergence zones near the ridge line of a high-pressure system. In their initial development stage, they were associated with high-value areas of pseudo-equivalent potential temperature at 400 hPa, while their maintenance and development were related to thermal convection and strong upward motion in the middle and upper levels. The vortex cloud systems moved eastward and southward into the Western Sichuan Plateau, where they continued to develop, serving as the primary systems responsible for the heavy precipitation. The two vortices were characterized by large-scale stratiform cloud echoes, moved slowly, and maintained nearly stationary precipitation echoes. Strong echo centers developed echo walls in the vertical direction, leading to intense localized rainfall.

     

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