Using conventional meteorological observational data,mesoscale automatic weather station data and Doppler radar data,the rainstorm event occurred in a large area in Hunan Province from June 18 to 20,2010 is analyzed,and the emphasis is on the analysis of Doppler radar echo characteristics of"train effect".The results are as follows.(1) The deep moist layer is the vapor source of high efficiency precipitation and the vertical wind shear in mid-lower level makes a contribution to the better organizing convection system,so that the strong precipitation lasts for a longer time leading to a heavy rainstorm.(2) The large area precipitation echo(greater than or equal to 40 dBz) with low center of mass and high efficiency is passing from the north of Hunan continuously making the"train effect"to lead to the rainstorm and even heavy rainfall in a large area north to the central Hunan.(3) The radial velocity characteristics with cold and warm advection superposed on convergence,meso-cyclone and low level jet make for the long maintenance of"train effect".(4) The timely identification of both strong precipitation echo and the"train effect"and the estimation of persistent time of the"train effect"are beneficial to warn and forecast rainstorm accurately and in time.%利用常规气象观测探测、中尺度自动气象站资料和多普勒天气雷达资料,对2010年6月18—20日湖南省大范围暴雨过程进行分析,着重分析该过程中＂列车效应＂的多普勒雷达特征。结果表明：深厚湿层是产生高降水率的水汽来源,中低层垂直风切变使对流系统具有高度的组织性,可使强降水维持更长时间,有利于大暴雨产生;低质心、高效率的大面积降水回波（≥40 dBz）较长时间源源不断从湘北经过产生＂列车效应＂,导致湘中以北大范围暴雨甚至大暴雨;冷暖平流和辐合相叠加的径向速度特征、中气旋、低空急流的维持使＂列车效应＂长时间维持;利用多普勒天气雷达快速识别强降水回波和＂列车效应＂并对其维持时间作出预测,可为及时、准确发布暴雨预警与预报提供可靠依据。
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