桂北地区前汛期两次极端强降水成因对比分析  

Comparative analysis of the causes of two extreme heavy rainfalls during the previous flood season in northern Guangxi

作　　者：潘仕球 唐小琴 唐熠[1] 欧阳荣谦 阳薇[1] 李向红[1] PAN Shiqiu;TANG Xiaoqin;TANG Yi;OUYANG Rongqian;YANG Wei;LI Xianghong(Guilin Meteorological Bureau,Guangxi Guilin 541001,China;Gongcheng Meteorological Bureau,Guangxi Gongcheng 542500,China)

机构地区：[1]桂林市气象局,广西桂林541000 [2]恭城县气象局,广西桂林542500

出　　处：《气象研究与应用》2023年第4期36-43,共8页Journal of Meteorological Research and Application

基　　金：广西气象科技重点项目(桂气科2022Z01);2022年桂林市重点研发计划(20220118-3)。

摘　　要：利用地面高空常规观测资料和欧洲中期天气预报中心(ECMWF)的全球气候第五代大气再分析数据(ERA5)资料,对2022年4月25—30日(“4·25”过程)和2023年5月21—22日(“5·22”过程)两个极端强降水过程进行分析,探讨两次过程的触发机制。结果表明:(1)两次过程均发生在500~700 hPa高原东侧有小波动发展的天气尺度下,“4·25”过程具有持续时间久、范围大、短时雨强大和夜雨特征明显的特征;“5·22”过程具有持续时间短、降水中心范围小、短时雨强大和夜雨特征明显的特征。(2)有利的环境条件为暴雨的形成提供较好的水汽和热力不稳定条件。但“5·22”过程环境条件更强,异常强的层结不稳定和抬升作用对“5·22”极端强降水的发展提供有利条件。(3)超低空急流建立强劲的水汽通道,两次过程的强降水中心存在水汽通量辐合大值区,超低空急流输送的暖湿气流为强降水的产生提供稳定持续的水汽条件。Two extreme precipitation processes,April 25—30,2022(the "4·25" process) and May 21—22,2023(the "5·22" process),are analyzed by using conventional ground-based upper-air observations and the ERA5 reanalysis data from the European Center for Medium-Range Weather Forecasts(ECMWF) to explore the triggering mechanisms of these two processes.April 25—30,2022( "4·25" process) and May 21—22,2023( "5·22" process) to explore the triggering mechanism of these two processes.The results show that:(1)Both processes occurr in the weather scale of 500~700 hPa with small fluctuations developing on the east side of the plateau,and the "4·25" process is characterized by long duration,large range,strong short-term rain and obvious night rain.The "5·22" process is characterized by a short duration,small range of precipitation center,strong short-term rain and obvious night rain.(2)The favorable environmental conditions provide better conditions in terms of water vapor and thermal instability for the formation of heavy rainfall.However,the environmental conditions of the "5·22" process are stronger,and the unusually strong laminar instability and uplift provide favorable conditions for the development of the extreme heavy precipitation on "5·22" process.(3)The ultra-low-altitude jet establishes a strong water vapor channel,and there is an area of large water vapor flux convergence in the center of heavy precipitation in the two processes,and the warm and humid air transported by the ultra-low-altitude jet provides stable and continuous water vapor conditions for the generation of heavy precipitation.

关 键 词：极端强降水 超低空急流 降雨特征 前汛期 

分 类 号：P426.6[天文地球—大气科学及气象学]