青藏高原东坡两次暴雨的MCS演变及机理对比分析  

MCS evolution and mechanism comparison in the two rainstorm events on the eastern slope of the Qinghai Tibet Plateau

作　　者：竹利 康岚 陈永仁[1,4] 吕俊杰 李晓容 周学云 ZHU Li;KANG Lan;CHEN Yongren;LYU Junjie;LI Xiaorong;ZHOU Xueyun(Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province,Chengdu 610072;Severe Weather in Northeast Sichuan Key Laboratory of Nanchong City,Nanchong 637000;Sichuan Provincial Meteorological Observatory,Chengdu 610072;Sichuan Meteorological Disaster Prevention Technology Centre,Chengdu 610072)

机构地区：[1]高原与盆地暴雨旱涝灾害四川省重点实验室,成都610072 [2]川东北强天气研究南充市重点实验室,南充637000 [3]四川省气象台,成都610072 [4]四川省气象灾害防御技术中心,成都610072

出　　处：《暴雨灾害》2024年第5期509-520,共12页Torrential Rain and Disasters

基　　金：中国气象局气象能力提升联合研究专项(22NLTSZ006);中国气象局复盘总结专项(FPZJ2024-114);高原与盆地暴雨旱涝灾害四川省重点实验室项目(SCQXKJYJXMS202208);四川省科技计划项目(2021YFS0326,2022YFS0543);南充市科技计划项目(21YFZJ0028)。

摘　　要：受MCS长时间影响下的暴雨天气在复杂地形区容易造成山洪等严重灾害,研究其特征及成因有助于更好地认识和防御类似的灾害天气。利用多源气象观测资料对青藏高原东坡复杂地形区2020年8月10—11日(过程1)和2021年8月4—5日(过程2)两次暴雨过程的降水特征和中尺度对流系统(MCS)演变特征及形成机理进行对比分析,结果表明:(1)两次过程均为弱天气尺度系统影响下的暖区暴雨天气过程,强降水落区均位于罗纯山脉西侧的平坝河谷地带,地形对强降水落区的影响十分明显;相较过程2,过程1降水强度更大、范围更广且降水落区更集中。(2)造成两次暴雨的MCS均在雅安西部的高海拔迎风坡初生,并在罗纯山西侧维持发展,但过程1的MCS尺度和强度更大、维持时间更长。(3)过程1的强降水主要由一尺度更大的对流性(积状云为主)MCS稳定少动造成,过程2则分别为两个相继发展的混合性(积云-层云混合)MCS经过同一地区造成。(4)两次过程中的MCS维持机制不同,过程1的主要机制为罗纯山地形强迫抬升作用下不断形成的深对流单体与原MCS_1A合并,使其长时间维持在罗纯山西侧,形成准静止后向建立型MCS回波带,同时地形对冷池出流的阻挡作用以及对暖湿气流的绕流作用也在一定程度上使得MCS_1A稳定少动。而过程2的MCS维持的主要机制为高海拔迎风坡地形反馈作用。The extreme heavy rainfall weather under the long-term influence of MCS can easily cause serious disasters such as flash floods in complex terrain areas.Detailed study of its characteristics and causes can help better understand and defend against similar disaster weather.In this paper,we use multi-source meteorological observation data to study the MCS evolution characteristics and mechanism of two rainstorm processes on 10-11 August 2020(process 1)and 4-5 August 2021(process 2)in the complex terrain area of the eastern slope of the Qinghai Tibet Plateau.The results are as follows.(1)The two processes are warm rainstorm weather processes under the influence of weak weather scale system,and the strong precipitation areas are located in the Pingba River valley to the west of Luochun Mountains.The terrain has a very obvious impact on the strong precipitation areas.Compared with process 2,process 1 has larger precipitation intensity,wider range and more concentrated distribution of precipitation areas.(2)The MCS that caused the two rainstorm both originated in the high altitude windward slope terrain in the west of Ya'an,and maintained development in the west side of Luochun Mountains,but the MCS of process 1 was larger in scale,intensity and duration.(3)The heavy precipitation in process 1 is mainly caused by a larger scale convective(mainly cumulus clouds)MCS with stable and less movement,while process 2 is caused by two successively developing mixed(cumulus layer cloud mixing)MCS passing through the same area.(4)The maintenance mechanism of MCS during the two processes is different.The main mechanism of Process 1 is the continuous formation of deep convective cells under the forced uplift of the Luochun Mountain terrain,which merge with the original MCS1_A and maintain it on the western side of Luochun Mountain for a long time,forming a quasi stationary backward established MCS echo zone;At the same time,the blocking effect of the terrain on the outflow of the cold pool and the bypass effect on the warm and humid

关 键 词：青藏高原 中尺度对流系统 维持机制 地形作用 冷池 

分 类 号：P445[天文地球—大气科学及气象学]