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    三个典型登闽空心结构台风强降水分布差异分析

    Analysis of heavy rainfall distribution difference among three typical hollow typhoons landing in Fujian province

    • 摘要: 利用常规气象观测资料和NCEP (National Centers for Environmental Prediction)再分析资料对1710“海棠”、1307“苏力”和0709“圣帕”这三个典型登闽空心台风分别于2017年7月31日、2013年7月13日和2007年8月19日产生的强降水分布差异采用诊断方法分析。结果表明:高层辐散分流通道显著不同,“海棠”与“圣帕”为反气旋性流出气流,“苏力”属于单一流出通道。环境风垂直切变方向对“海棠”与“苏力”大降水落区有一定预报指示意义。湿度锋区及干舌侵入位置的差异对三个台风空心结构形成及强降水分布的差异有重要影响。湿位涡场均呈现下负上正分布,表明大气在低层为对流不稳定状态。湿正压项是“海棠”与“圣帕”台风MCS发展的主要不稳定条件,而湿正压项和湿斜压项均对“苏力”台风MCS发展起加强作用,其中湿正压项对MCS非对称分布起主要作用。

       

      Abstract: Base on conventional meteorological observations and the National Centers for Environmental Prediction (NCEP) reanalysis data,the heavy rainfall distribution differences among three typical hollow typhoons (1710 “Haitang” on July 31,2017,1307 “Soulik” on July 13,2013,and 0709 “Sepat” on August 19,2007) landing in Fujian province were diagnostically analyzed.The results show that the divergence channels at high altitudes of the three typhoons are significantly different;typhoons of “Haitang” and “Sepat” both exhibit anticyclone outflows,while “Soulik” only has a single outflow channel.Vertical wind shear direction is useful to predict heavy rainfall area of typhoons “Haitang” and “Soulik”.The front zone of moisture and the intruding location of dry tongue greatly influence the formation of hollow structures and the difference in distributions of strong precipitation.The moist potential vorticity of the three typhoons is negative at low altitudes and positive at high altitudes,indicating a convectively unstable condition of the atmosphere at low altitudes.Wet positive pressure term provides major unstable conditions for the development of mesoscale convective systems (MCS) of “Haitang” and “Sepat”,while the wet positive pressure term and the wet baroclinic term both strengthen the development of MCS of “Soulik”,and the former term plays an important role in the formation of an asymmetric distribution of MCS.

       

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