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投稿时间：2021-01-30 修订日期：2021-07-10
投稿时间：2021-01-30 修订日期：2021-07-10
中文摘要: 利用Himawari-8卫星、银川C波段多普勒雷达、ERA5逐1 h再分析、自动气象站、常规气象探测等多源气象资料，对2019年8月贺兰山东麓夜间突发的一次局地短历时强对流暴雨的中尺度特征进行分析。结果表明：700 hPa偏南急流于暴雨前6 h建立并在夜间增强北抬，促进了低层高温高湿、大气不稳定和动力、热力抬升机制的发展加强，有利于地面中尺度辐合线在东麓山前触发β中尺度对流系统，并使其增强为α中尺度对流系统，导致此次强对流暴雨的发生发展；暴雨区位于700 hPa 急流轴左前方及700 hPa水汽通量≥6 g·cm-1·s-1·hPa-1和850 hPa比湿≥12 g·kg-1的高湿区,对流有效位能≥1 〖KG-*5〗500 J·kg-1和850 hPa假相当位温≥346 K的高温高能区，800 hPa中心强度≤-1.2 Pa·s-1的上升运动区和冷云发展前端辐射亮温梯度大值区；最大小时降水量出现在急流轴离暴雨区最近时段，期间辐射亮温≤-66℃、辐射亮温梯度≥27℃·km-1、回波强度≥65 dBz、回波顶高≥10 km、垂直累积液态水含量≥11 kg·m-2、≤-52℃冷云面积约为中尺度对流复合体的1/5；辐射亮温越低、辐射亮温梯度越大、降温率越高，小时降水量越大；最低辐射亮温、最大辐射亮温梯度、回波强度和垂直累积液态水含量跃增、回波顶高增幅加大均较强降水提前10~20 min出现，地面中尺度辐合线较降水提前30 min出现。
中文关键词: 对流性暴雨，中尺度对流系统，辐射亮温梯度，低空急流
Abstract:The mesoscale characteristics of a local short-time severe convective rainstorm that occurred at the eastern foot of Helan Mountains in Ningxia in August 2019 are analyzed based on the data from Himawari-8 satellite, C-band Doppler radar, ERA5 hourly reanalysis, automatic weather station and conventional observation data. The results show that the southerly jet at 700 hPa, which was formed 6 h before the rainstorm and strengthened at night, contributed to the high temperature, the high humidity, the enhancement of atmospheric instability and the dynamic and thermal uplift mechanisms in the lower layers of the rainstorm area. It also helped mesoscale ground convergence line to trigger the meso-β scale convective system in the eastern slope of Helan Mountains and strengthen it into meso-α scale convective system, leading to the generation and development of the severe convective rainstorm eventually. The rainstorm occurred in the front-left of jet axis at 700 hPa, the high humidity area with water vapor flux ≥6 g·cm-1·s-1·hPa-1 at 700 hPa and specific humidity ≥12 g·kg-1 at 850 hPa, the high energy area with convective available potential energy (CAPE) ≥1 〖KG-*5〗500 J·kg-1, the high temperature area with θse ≥346 K at 850 hPa, the vertical upwarding area with central intensity ≤-1.2 Pa·s-1 at 800 hPa, and the front of cold cloud where the large gradient (G) of radiation brightness temperature (TBB) occurred. During the heaviest rainfall period, the jet axis was closest to the rainstorm area, the TBB ≤-66℃, G ≥27℃·km-1, the radar echo intensity (Z) ≥65 dBz, the echo heights (H) ≥10 km, the vertical integrated liquid water (VIL) ≥11 kg·m-2, and the area of the cold cloud below -52℃ was about 1/5 of mesoscale convective complex. The lower the TBB, the large the G, the higher the cooling rate and the more the hourly precipitation. The minimum TBB, the maximum G, the leap of Z and VIL, and the increase of echo height appeared 10-20 min earlier than the maximum rainfall, and the mesoscale ground convergence line appeared 30 min earlier than the rainfall.
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基金项目:国家自然科学基金项目（41965001）、宁夏回族自治区科技创新领军人才培养工程（2021GKLRLX05）、宁夏回族自治区第五批青年科技人才托举工程（NXKJTJGC2021089）和宁夏回族自治区自然科学基金项目（2019AAC03256）共同资助
引用文本：
张晓茹,陈豫英,姚姗姗,苏洋,杨银,2022.贺兰山东麓一次局地强对流暴雨的中尺度特征[J].气象,48(7):801-812.
ZHANG Xiaoru,CHEN Yuying,YAO Shanshan,SU Yang,YANG Yin,2022.Mesoscale Characteristics of a Local Severe Convective Rainstorm at the Eastern Foot of Helan Mountains[J].Meteor Mon,48(7):801-812.
张晓茹,陈豫英,姚姗姗,苏洋,杨银,2022.贺兰山东麓一次局地强对流暴雨的中尺度特征[J].气象,48(7):801-812.
ZHANG Xiaoru,CHEN Yuying,YAO Shanshan,SU Yang,YANG Yin,2022.Mesoscale Characteristics of a Local Severe Convective Rainstorm at the Eastern Foot of Helan Mountains[J].Meteor Mon,48(7):801-812.
