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边界层急流在粤东暴雨中心两次极端强降水过程中的作用
陈芳丽
(惠州市气象局)
The role of boundary layer jet in two severe rainfalls in eastern region of Guangdong
Chen Fangli
(Meteorological Bureau of Huizhou City)
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投稿时间:2020-02-25    修订日期:2020-07-29
中文摘要: 极端强降水极易致灾,华南沿海极端强降水的发生与边界层急流密切相关,目前对于极端强降水的预报预测仍是业务重点和难点。本研究基于广东省气象观测资料和全球再分析资料CSFR,分析了2013年8月和2018年8月发生在粤东暴雨中心的破纪录极端强降水过程,阐明边界层急流的作用。结果表明:(1)两次过程的主要影响系统分别为长时间缓慢移动的1311号台风“尤特”残余环流和季风低压外围环流,当粤东暴雨中心处于台风环流东南侧和季风低压东侧时,边界层急流在该区域辐合抬升,形成明显的中尺度能量锋,从而增强了该区域大气斜压性,这种大气环流形势非常有利于强降水的触发和维持;(2)边界层急流为强降水提供了充沛的、源源不断的水汽条件,同时配合特殊地形的摩擦、阻挡等作用,粤东暴雨中心内形成了明显的水汽通量辐合;(3)较弱的边界层风垂直切变和显著的温度锋区,使得粤东暴雨中心内大气一直处于不稳定状态,长时间大气层结不稳定有利于强降水的维持;(4)粤东暴雨中心内地面中尺度辐合线的维持或北抬,有利于强降水回波不断触发和维持。两次过程中不同点主要表现为边界层急流强度和风向不同,由此带来的气流辐合方式和强降水范围有明显的差异,季风低压影响过程中边界层急流作用更显著。研究结果有助于认识粤东暴雨中心极端强降水形成机制,为今后该区域防灾减灾提供有力的气象保障服务水平。
Abstract:Extremely severe precipitation would cause disaster easily.The occurrence of extremely severe precipitation in the south China coast is closely related to the boundary layer jet stream.At present, the forecast of extremely heavy precipitation is still the emphasis and difficulty in service.This study is based on meteorological monitoring stations in Guangdong Province and global reanalysis data CFSR,and the process of two record-breaking extremely severe precipitation events of August 2013 and August 2018 in eastern region of Guangdong is analyzed, to expound the effect of boundary layer jet.The result is shown as follows.(1)The main influence systems of the two processes respectively were the long slowly moving residual circulation of typhoon Utor and outer circulation of monsoon depression.When the eastern region of Guangdong was located on the southeast side of typhoon circulation or the east side of monsoon depression,the convergence and uplift of boundary layer jet formed a clear mesoscale energy front,and the atmospheric baroclinicity of that region was enhanced,the severe rainfall was under favorable conditions to trigger and maintain.(2)Boundary layer jet provides abundant and continuous water vapor conditions for heavy rainfall,cooperated with the effect of special topographic friction and countercheck,remarkable convergence of water vapor flux was formed in the in eastern region of Guangdong.(3)Weak boundary layer wind vertical shear and the significant temperature front made atmosphere in eastern region of Guangdong to keep an unstable state.Long time instability of the stratified atmosphere was conducive to the maintenance of severe rainfall.(4) The maintenance or northward moving of surface mesoscale convergence lines made the echoes of heavy rainfall constantly trigger and maintain.The difference between the two processes mainly showed as difference of the boundary layer jet intensity and the wind direction,thus the way of airflow convergence and scope of severe rainfall were significantly different.The role of boundary layer jet performed more significantly during the influence process of monsoon depression.The study results are helpful to understand the formation mechanism of extremely heavy precipitation in the rainstorm center in eastern region of Guangdong,and to provide strong meteorological safeguard and service in future.
文章编号:202002250052     中图分类号:    文献标志码:
基金项目:广东省自然科学基金(2019A1515010814)、中国气象局预报员专项项目(CMAYBY2020-091)和广东省气象局科研项目(GRMC2017M29)资助
引用文本:
陈芳丽,0.The role of boundary layer jet in two severe rainfalls in eastern region of Guangdong[J].Meteor Mon,():-.
Chen Fangli,0.The role of boundary layer jet in two severe rainfalls in eastern region of Guangdong[J].Meteor Mon,():-.