一次准静止中尺度对流系统维持机制研究  

Study on the Maintenance Mechanism of a Quasi-Stationary Mesoscale Convective System

作　　者：王啸华 郑媛媛 张盛曦 慕瑞琪 吕润清 WANG Xiaohua;ZHENG Yuanyuan;ZHANG Shengxi;MU Ruiqi;LYU Runqing(Nanjing University,Nanjing 210023;Nanjing Joint Institute for Atmospheric Sciences,Nanjing 210009;Jiangsu Meteorological Observatory,Nanjing 210044)

机构地区：[1]南京大学,南京210023 [2]南京气象科技创新研究院,南京210009 [3]江苏省气象台,南京210044

出　　处：《气象》2021年第11期1369-1379,共11页Meteorological Monthly

基　　金：国家重点研发计划(2018YFC1507503);江苏省“333工程”科研项目(BRA17521)共同资助。

摘　　要：2016年7月7日凌晨,受中尺度对流系统(MCS)影响,南京出现突发性局地特大暴雨,MCS发展持续近8 h,包括对流触发、准静止后向传播、强降水超级单体和冷池驱动四个阶段,造成严重内涝。利用多普勒雷达、自动站、风廓线、中国区域再分析、江苏融合同化分析等多源资料详细分析造成这次强降水过程的天气背景和MCS的演变特征,结果表明中尺度前倾高空槽过境诱发地面低压,加强了地面辐合,形成上升运动,触发了线性对流风暴。3~6 km高度西南气流显著增强,β中尺度次级环流左侧被抬升和γ中尺度低层低压与西南气流的有利配置,使得南京上空MCS表现出后向传播的准静止特征,最终发展成为持续8个"雷达体扫"时长的强降水超级单体。强降水超级单体中强降水拖曳作用形成下沉气流,导致近地面出流,在南侧激发新的对流,MCS缓慢向南移动。随着MCS内下沉气流加强,地面出现冷池,强烈地面辐散加速MCS移动,强降水过程结束。In the early morning of 7 July 2016,due to the influence of mesoscale convective system(MCS),a sudden local rainstorm occurred in Nanjing.Development of the MCS including convection triggering,quasi-stationary backward propagation,heavy rainfall supercell and cold pool driving lasted for nearly 8 hours,resulting in serious waterlogging.The synoptic background and MCS evolution characteristics of this heavy rainfall process are analyzed in detail by using multi-source datasets from Doppler radar,automatic stations,wind profile,China regional reanalysis(CNRR),Jiangsu merged assimilation analysis and so forth.The results show that a mesoscale forward-tilting trough induced low pressure at the surface,strengthening convergence,forming an uplifting movement and triggering linear convective storms.The warm and humid southwesterly flow between 3 km and 6 km was significantly enhanced.The favorable configuration of the uplifted left side of meso-βscale secondary circulation,the meso-y scale low-level low pressure and the southwesterly flow made the MCS over Nanjing exhibit a quasi-stationary feature of backward propagation,eventually leading to a heavy precipitation supercell in eight consecutive radar volume scans.The drag effect of heavy precipitation formed a downdraft,which led to the outflow near the surface and stimulated a new convection on the south side,causing the MCS to move slowly to the south.As the downdraft strengthened in the MCS,a cold pool appeared on the ground.The strong divergence accelerated the movement of the MCS,and then the heavy precipitation process ended.

关 键 词：中尺度对流系统(MCS) 后向传播 强降水超级单体 冷池 

分 类 号：P458[天文地球—大气科学及气象学]