首页|华南前汛期一次锋前暖区暴雨成因及中尺度对流系统分析

华南前汛期一次锋前暖区暴雨成因及中尺度对流系统分析

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  • 国家科技期刊平台
  • NETL
  • NSTL
  • 万方数据
  • 维普
2020年3月27日华南地区发生一次典型的锋前暖区暴雨过程,过程持续超过15 h,出现中尺度对流系统MCS-A、MCS-B与MCS-C并产生多次分裂与重组.利用地面自动站数据、多普勒天气雷达资料、ECMWF-ERA5地面和高空再分析场资料,结合中尺度CMA-GD模式对此次暖区暴雨过程环流形势与中尺度对流系统组织特征和触发条件等方面进行分析.结果表明:(1)高低空环流包括500 hPa高空槽、200 hPa西风急流与锋前低槽等系统的有利配置且稳定少动是暖区暴雨长时间维持的重要原因.持续维持的低空急流为对流发生发展提供了有利的条件性不稳定和对流有效位能.(2)伴随自由对流高度降低与CIN抑制能量减小,贺州至怀集一带的关键区域1处对流在地面得以触发,而距离1处南向约80 km的关键区域2中1 500m高度处风速辐合与冷池作用使得对流发生.(3)MCS-A与MCS-B在关键区域1处触发,呈现前向与后向传播,MCS-C在关键区域2处触发后以后向传播为主.此外,MCS-B与MCS-C表现为多条平行排列的南北向短雨带并产生向东移动的"列车带效应",而MCS-A与MCS-B则表现为多次分裂与重组后形成向东南移动的"列车带效应".(4)中β尺度次级环流的上升支抬升西南暖湿气流,使其倾斜上升凝结潜热释放,造成后向传播对流系统的发生发展.同时由于强降水拖曳作用,850 hPa以下转下沉气流造成一定厚度的冷池后与暖湿入流叠加,触发新对流单体,也影响后向传播.(5)上游MCSs发生后在地面形成冷池出流,与暖湿气流辐合抬升,造成前端对流触发.
ANALYSIS OF CAUSATION AND THE MESO-SCALE CONVECTIVE SYSTEMS IN A STRONG HEAVY RAINFALL IN WARM SECTOR AHEAD OF FRONTS IN SOUTH CHINA
The evolution of three mesoscale convective systems(MCS),i.e.,MCS-A,MCS-B,MCS-C,experienced multiple division and reorganization,resulting in a heavy rainfall in the warm sector ahead of fronts in Southern China on 27 March 2020,which sustained for more than 15 hours.The synoptic background,organization modes and initiation conditions of MCS are analyzed by using surface automatic meteorological stations data,Doppler weather radar data,ERA-Interim reanalysis data and mesoscale CMA-GD model data.The results are shown as follows.(1)Favorable configuration and stable circulation systems,including a 500 hPa upper-level trough,a 200 hPa westerly jet and a frontal trough are important reasons for long-term maintenance of the warm-sector heavy rainfall.The low-level jet provides conditional instability and convective available potential energy for the generation and development of convection.(2)The convection in key region 1 from Hezhou to Huaiji was triggered on the ground with the decrease of the level of free convection and the reduction of CIN energy.The interaction between wind speed convergence at the height of 1500 m and a cool pool in key region 2 80 km away from key region 1 resulted in the convection.(3)MCS-A and MCS-B are modulated into forward and backward propagation in key region 1,while MCS-C is modulated into backward propagation in key region 2.The convective cells of all three MCSs form echo"train band effects".In addition,both MCS-B and MCS-C form several short and parallel convective rainbands in a nearly N-S direction triggering eastward"train band effects".MCS-A and MCS-B split again into short and parallel convective rainbands in a nearly NE-SW direction triggering southeastward"train band effects".(4)The warm and humid southwesterly flow on the left side of the meso-β-scale secondary circulation is lifted,releasing latent heat and triggering convection.The interaction of the cold outflow resulting from the drag effect of heavy precipitation formed a downdraft below 850 hPa and a warm inflow on the west side near the surface was conductive to new convection,which was the development mechanism of the backward propagation.(5)Forward propagation was caused by the convergence between the cold pool outflow,which was formed on the ground after the genesis of upstream MCSs,and the warm moist flow.

warm-sector heavy rainfallmesoscale convective system(MCS)forward propagationtrain effectcool pool

张兰、陈炳洪、张东、魏蕾、杨慧燕、余锐

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广州市气象台,广东 广州 511430

广东省气象台,广东 广州 510641

三水区气象局,广东 佛山 528100

暖区暴雨 中尺度对流系统 前向传播 列车效应 冷池

国家自然科学基金国家自然科学基金广东省重点领域研发项目广东省自然科学基金广东省智能网格预报技术团队广东省气象局科技项目广州市科技计划项目

42075190418751822020B11112000012020A1515010602GRMC2019M25201903010101

2023

10.16032/j.issn.1004-4965.2023.061

热带气象学报
中国气象局广州热带海洋气象研究所

热带气象学报

CSTPCDCSCD北大核心
影响因子：0.768
ISSN：1004-4965
年,卷(期)：2023.39(5)
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