2009-08-17山东特大暴雨雷达回波及地形作用分析

A study on radar-echo and the impact of terrain on the heavy torrential rainfall event in Shandong Province on 17 August 2009

利用常规、非常规资料对2009年8月17—18日山东省出现的特大暴雨过程进行分析。结果表明:"8.17"特大暴雨主要出现在西风槽东移、副高南退时的副高西北侧边缘,对流有效位能(CAPE)等热力环境指数对鲁南强降水有较强的反应能力。降水分布具有典型的地形影响特征,复杂山地地形对降水有显著增幅作用和对对流系统传播的阻碍作用。存在低空急流和列车效应,强回波维持时间较长是费县出现强降水的重要原因,较强的偏南气流、湿度层深厚是费县出现特大暴雨的根本原因。地形影响气流理论很好地解释了山东"8.17"特大暴雨降水分布,费县特殊地形对特大暴雨有很大贡献。雷达资料可以弥补常规观测的不足;地形对强降雨及其分布有重要影响。

A heavy torrential rainfall process during August 17 and 18,2009 is analyzed by using both normal and abnormal data such as radar data.The results show that：1）the torrential rainfall mainly occurred in the border district of northwest subtropical high when the trough moved eastward and the subtropical high moved backward to the south;2）some thermal environmental indexes like CAPE presented good corresponding relationship with intensive rainfalls in south Shandong province;3）distribution of precipitation was profoundly affected by the topographic condition;the complex topography of mountains in Shandong Province can lead to significant precipitation amplification and block the movement of the convective systems;4）low jet stream and train effects existed in the torrential rainfall;the strong radar-echo lasting for a long time is the main reason for the heavy rain in Feixian;the strong southerly flow and the thick moist air are the leading factors for the torrential rainfall;5）the theory of the impact of terrain on precipitation well explains the distribution of precipitation in this torrential rainfall progress;6）the special terrain of Feixian contributes to the heavy rainfall greatly.Radar data is a good supplement to normal observational data.The impact of terrain exerts important influence on strong precipitation and its distribution.