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台风远海北上背景下江苏一次大暴雨过程的中尺度分析

Mesoscale analysis of an extremely heavy rain event in Jiangsu due to the effect of coastal northward-moving typhoon

  • 摘要: 利用常规观测资料以及江苏省区域自动站资料、多普勒天气雷达和风廓线雷达资料、FY-2F卫星云图与NECP 1°×1°再分析资料, 对2014年8月7-8日发生在江苏的一次大暴雨天气过程进行了中尺度分析。结果表明:(1)该过程是在1411号台风"夏浪"北上、贝加尔湖高压脊建立、东北低槽东移南压的天气背景下发生的, 其中两个强降水中心分别位于大丰市大桥镇和南通市幸福镇, 最大雨强均为109.2 mm·h-1; (2)地面冷锋和辐合线触发对流风暴, 对流风暴受低空风作用移动缓慢, 造成大丰市大桥镇短时强降水; (3)地面中尺度涡旋东移到南通沿江地区, 受地形作用而稳定少动, 在有利的环境垂直风切变条件下, 其右侧触发多个对流风暴单体, 造成南通市幸福镇短时强降水; (4)初始对流云团的生成信息, 对强降水临近预报有一定的指示意义。

     

    Abstract: Based on routine upper-air and surface observations, observations from intensive automatic weather stations over Jiangsu, Doppler weather radar and wind profile radar data, FY-2F satellite cloud images, and NCEP/NCAR reanalysis with 1°×1° resolution, we have conducted a mesoscale analysis of an extremely heavy rain event occurred in Jiangsu from August 7 to 8 in 2014.The results indicate that (1) this event, in which two severe precipitation areas with the greatest rainfall intensity of 109.2 mm·h-1 located in the Daqiao town of Dafeng City and the Xingfu town of Nantong City, respectively, occurred under the influence of a coastal northward-moving typhoon (1411) Halong, the establishing of a ridge at Lake Baikal and the eastward moving and southward jumping of the Northeast China trough.(2) The short-period severe precipitation at Daqiao town was attributed to slowly-moving convective storms triggered by surface cold front and convergence line, and coordinated with low-level wind.(3) The short-period severe precipitation at Xingfu town was caused by several convective storm cells.Surface mesoscale vortex, which moved eastward along the Yangtze River in Nantong, then became stable and stationary due to the effect of advantageous topography and environmental vertical wind shear, triggered these cells.(4) The initial generation of convective cloud clusters has an indicative significance to the nowcasting of severe precipitation.

     

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