海南岛“0810”特大暴雨物理量诊断及多普勒特征分析

Doppler Echo Characteristics and Physical Diagnosis of "0810" Heavy Storm in Hainan Island

应用常规观测、海口多普勒回波及NCEP1×1°再分析等资料,对2008年10月12～15日海南特大暴雨成因进行诊断分析,并揭示了暴雨过程中的多普勒回波特征。结果表明:导致海南岛产生强降水的主要原因是热带低压移动缓慢和弱冷空气的低层入侵;当冷暖空气交绥,大气温湿结构发生突变,θse面陡立造成对流系统斜压发展,激发位势不稳定能量释放。正差动假相当位温平流意味着低层暖湿空气的平流大于高层,加强了层结对流不稳定发展;在斜压扰动作用下,对流层中层正差动涡度平流和低压东侧的暖平流破坏了海南岛的准地转平衡,动力强迫和热力强迫共同作用激发了次级环流,导致暴雨区上空的垂直运动的发展,促使暴雨增强。充沛的水汽输送及水汽的强烈辐合,为暴雨发生的有利水汽条件。多普勒径向速度揭示了暴雨区低层冷平流高层暖平流、风向风速的垂直切变大的垂直结构以及持续性的强烈辐合等等特征,回波停滞和"列车效应"使降水增幅,降水回波的性质差异,可造成强降水区域分布的不同。

Application of conventional observations,Doppler Echo data and NCEP1×1° reanalysis data,etc.the heavy rain in Hainan Island between 12～15 October 2008 was analyzed.The results show that the heavy rainfall is mainly due to slow moving tropical depression and low-level cold air intrusion.The vertical structure of pseudo-equivalent potential temperature is change when the convergence of cold and warm air,result in the baroclinic convective system development and instability energy release.Under the action of Baroclinic disturbance,the middle troposphere is the differential vorticity advection and the warm advection in east of low pressure destroy the quasi-geostrophic balance.Then dynamic and thermal interaction stimulated the secondary circulation,which lead to vertical motion over the storm zone development,storm enhancement.The favorable conditions of heavy rain is the strong convergence of water vapor.Doppler radial velocity reveals such characteristics as the low-level cold advection with high-level warm advection,the vertical wind shear in the vertical structure and persistent the strong convergence,etc.Doppler echo stagnation and the＂train effect＂increase precipitation.the differences of precipitation echoes nature can cause the different regional distribution of heavy rainfall.