马关县三次不同背景下暴雨成因和雷达特征分析
Analysis of Causes and Radar Characteristics of Three Heavy Rain Events in Maguan under Different Synoptic Situations

本文利用ERA5 0.25？ × 0.25？逐小时的再分析资料、Micaps国家站和区域自动站气象要素资料、文山雷达资料等，对马关地区三次不同背景下的暴雨过程天气背景、成因及雷达特征进行了分析，结果表明：个例1是一次台风残余低压暴雨，个例2是副高边缘型暴雨，个例3是低涡切变型暴雨。天气系统稳定造成降水时间长，是形成三次暴雨的重要原因。分析探空特征可见，三次个例均有一定的对流能量，对流抑制小，抬升凝结高度低，K指数在40℃附近，SI指数<0℃。个例1和个例3湿层深厚，有利于短时强降水的出现，个例2中400 hPa有干冷空气有利于出现短时强降水和大风。分析暴雨成因可见，降水受水汽、垂直运动加强而加强，且水汽和垂直运动增强可较降水增强提前1~2小时。另外，位势不稳定触发也可增强降水。雷达特征上，个例1和个例2以层状云降水为主，最大反射率因子超过40 dBZ。马关地区持续受回波影响，形成列车效应。垂直剖面上，回波质心低。径向速度特征上，个例1中有“S”形特征，说明有暖平流；个例3中有风场的切变。个例2中最强时段降水有对流性，19日17点11分回波呈块状，中心强度超过50 dBZ。垂直剖面上，马关回波发展高度较高，可伸展至7~8 km高度。径向速度图上有速度辐合，辐合层厚度超过5 km。
Three heavy rainfall events in Maguan, Yunnan Province were investigated through integrated analysis of multi-source datasets, including hourly ERA5 reanalysis data (0.25？ × 0.25？ resolution), surface observations from MICAPS national stations and regional automatic weather stations (AWS), and Doppler radar data from Wenshan. The synoptic configurations, physical mechanisms, and radar characteristics were analyzed under three distinct meteorological backgrounds. The results showed that: case 1 was under a typhoon remnant low-pressure system, case 2 was under the western periphery of the subtropical high, and case 3 was under a low-level vortex and shear line complex. Quasi-stationary synoptic patterns sustained prolonged rainfall. Sounding data exhibited a certain amount of convective available potential energy, low convective inhibition and lifting condensation levels, with K index around 40？C, and SI index less than 0？C. Deep saturated layers in cases 1 and 3 promoted high precipitation efficiency, while mid-level dry intrusion at 400 hPa in case 2 enhanced downdraft. The analysis of the causes of rainstorms showed that precipitation was strengthened by the enhancement of water vapor and vertical motion, and the enhancement of water vapor and vertical motion could be 1~2 hours earlier than the enhancement of precipitation. In addition, unstable potential triggering could also enhance precipitation. Radar observations showed that in case 1 and case 2, precipitations were dominated by stratocumulus, with a maximum reflectivity exceeding 40 dBZ. Maguan continued to be affected by echoes, forming a train effect. On the vertical section, the center of mass of the echo was low. In terms of radial velocity characteristics, there was an “S”-shaped