云南哀牢山东侧一次突发性暴雨过程诊断分析

摘要

利用加密自动站资料、NCEP每6 h再分析资料和FY-2 C红外TBB等资料，对2012年6月15日发生在哀牢山东侧突发性暴雨进行诊断分析。结果表明：700 hPa切变线移到哀牢山后受滇缅脊和地形阻挡形成与山脉同向的切变线，地面冷锋移到哀山东侧后形成静止锋，受不断南下冷空气补充，形成冷空气下沉，暖湿气流上升，出现强烈的上升运动。切变线附近辐合云带内形成的中尺度对流云团在高空西北气流引导下产生的“列车效应”导致了突发性暴雨发生。来自东海和孟加拉湾水汽在切变线附近交汇，受切变线两侧风向辐合产生强烈的水汽辐合，并在哀牢山附近形成深厚的水汽辐合层，是本次突发性暴雨天气的主要水汽特征。逐小时地面自动站海平面气压场和对流有效位能在哀牢山沿线突发性暴雨发生前有明显变化，强降水主要发生在地面中尺度暖低压附近和对流有效位能高值区，此分析对此类短时强降水预报和预警具有一定指示意义。%Based on the dense observation data,NCEP reanalysis and infrared TBB data,the system fea-tures and the cause for the rainstorm process on the east side of Ailao Mountain on 15 June 2012 have been diagnostically analyzed.The results show that the shear line at 700 hPa becomes the shear line parallel to Ailao Mountain after it moves to the mountain because of Yunnan-Burma ridge and terrain.The surface cold front becomes stationary front after it moves to the east side of Ailao Mountain.At the same time, surface cold air is supplied from north,cold air sinks and warm air increases,so strong ascending motion takes place.The mesoscale convective cloud cluster that forms in the convergent cloud belt near the shear line produces “train effect”,guided by the northwest flow and results in convective rainstorm.The vapor from East China Sea and Bay of Bengal converges at the nearby shear line.Deep moisture convergence lay-er caused by wind convergence nearby Ailao Mountain is main vapor characteristic in this sudden rain-storms weather.The hourly surface automatic station sea level pressure field and CAPE have significant changes before the occurrence of sudden rainstorm along Ailao Mountain,severe precipitation primarily happens near mesoscale surface warm depression and high value area of CAPE.These results would be in-dicative to the forecasting and warning of this type short-time severe precipitation.