An Extreme Rainfall Event in Coastal South China during SCMREX-2014: Formation and Roles of Rainband and Echo Trainings
An Extreme Rainfall Event in Coastal South China during SCMREX-2014: Formation and Roles of Rainband and Echo Trainings
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SCMREX-2014期间华南沿海的一次极端降雨事件：雨带和回波训练的形成和作用
DOI：
10.1029/2018jd028418
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
张大林
中科院分区：
文献类型：
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作者：
刘希;罗亚丽;管兆勇;张大林
利用双多普勒雷达、偏振雷达、广泛的中尺度网络和增强的高空探测资料，对2014年5月11日华南季风降水试验期间华南沿海地区20小时内451 mm的极端降水过程进行了研究。结果表明，极端降水的产生是由两个连续的中尺度对流系统（MCS）组成的多个中β尺度雨带。这两个MCS是通过提升向南的海洋流越过准静止的中尺度流出边界（MOB）来维持的，该边界沿着海岸线，并通过对流产生的弱冷池来增强。对流单体在环境西南气流的影响下向东北方向的“回波训练”，导致了各MCS中多雨带的形成。它们随后以“雨带训练”的形式传播，加上沿沿着的回声训练，是极端降雨的产生原因。第二个MCS的特征是一个主导的弓形雨带，表现出快速分裂和重建（RSRE）的过程，这有助于雨带训练的形成。RSRE过程的发生需要大量的不稳定上游海洋气团、准静止MOB以及与MOB相交的弓形雨带。第二个MCS比第一个MCS产生更多的降水，这是由于更多的雨带，更强的对流强度和更多的中等大小的雨滴，最大尺寸更大。上述研究结果，特别是RSRE过程及其相关的风暴内环流，似乎增加了新的见解的形成和维持训练雨带及其在暴雨生产中的作用。
In this study, an extreme rainfall event of 451 mm in 20 hr that occurred in coastal South China on 11 May 2014 during the Southern China Monsoon Rainfall Experiment is investigated using integrated observations from the dual‐Doppler radar pair, polarimetric radar, extensive mesonetwork, and enhanced upper‐air soundings. Results show the generation of the extreme rainfall by two consecutive mesoscale convective systems (MCSs) consisting of multiple meso‐β‐scale rainbands. The two MCSs are maintained by lifting southerly oceanic flows over a quasi‐stationary mesoscale outflow boundary (MOB) along the coastline that are enhanced by convectively generated weak cold pool. Northeastward “echo training” of convective cells, under the influence of environmental southwesterly flows, leads to the formation of the multiple rainbands in each MCS. Their subsequent propagations in a “rainband training” form, together with the echo training, along the coastline account for the production of extreme rainfall. The second MCS is characterized with a leading bowing rainband showing a process of rapid splitting and reestablishment (RSRE), which contributes to the formation of the rainband training. The occurrence of the RSRE process requires ample supply of unstable upstream oceanic air mass, the quasi‐stationary MOB, and a bowing rainband intersecting with the MOB. The second MCS produces more precipitation than the first one as a result of more rainbands, stronger convective intensity, and more moderate‐sized raindrops with larger maximal sizes. The above findings, especially the RSRE process and its associated storm internal circulation, appear to add new Insights into the formation and maintenance of training rainbands and their roles in heavy rainfall production.