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一次远距离台风影响下的对流性暴雨分析

Analysis of convective storm rainfall under influence by a distant Typhoon

  • 摘要: 用常规地面高空观测、中尺度自动气象站、卫星云图以及NCEP 的1°×1°再分析资料,对2011 年10 月13—14 日江西省南部出现的区域性暴雨过程进行分析。结果表明:(1) 此次降水过程是中纬度西风槽与台风倒槽相互作用的结果,槽前正涡度平流与低层台风倒槽东侧正涡度平流同位相叠加,增强了中低层动力抬升条件,台风东侧的偏南气流将水汽输送到暴雨区;(2) 高空槽携带干冷空气入侵与低层台风倒槽的暖湿气流叠加增强了大气的不稳定性,同时中高层有干空气侵入,高空位涡异常下传和低层位温异常利于气旋的发生和发展;(3) 地面非均匀加热使得强暴雨区地面出现异常负变压中心,形成变压风辐合和地面中尺度涡旋,触发对流性强降水;(4) 该过程共有3 个云团产生,中尺度对流云团在地面能量锋区南侧发生,沿能量锋区东移合并,经过高能中心时得到强烈发展。

     

    Abstract: By using routine observational data, meso-scale weather station data, Doppler radar products, satellite products and NCEP reanalysis data, a heavy rainfall event occurred during October 13 to 14, 2010 in Jiangxi was analyzed in detail. Results are as follows. (1) The rainfall event was caused by the combination of a Typhoon inverted trough and a mid-latitude westerly upper trough. The dynamic lifting was enhanced because the westerly trough is in phase with the inverted trough. Southerly airstream at the east side of Typhoon transports water vapor into the storm zone. (2) Dry and cold air of the upper trough intruded into the warm and wet flow, which enhanced the convective instability.The genesis and development of the depression were favored by the downward transport of potential vortex and low-level abnormal potential temperarure. (3) The negative change of surface pressure formed a meso-scale system which triggered the convection precipitation. (4)There were 3 convective cloud clusters developed along the south side of the energy front. Meso-scale convective cloud clusters moved along the front and were enhanced when passing the high energy center.

     

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