广西防城港沿海6·16特大暴雨成因及机制探讨  

DISCUSSION ON CAUSE AND MECHANISM OF TORRENTIAL RAIN ON JUNE 16,2020 IN COASTAL AREAS OF FANGCHENGGANG IN GUANGXI ZHUANG AUTONOMOUS REGION

作　　者：陈绍河 郑凤琴 蔡悦幸 赵胜男 唐盛 CHEN Shaohe;ZHENG Fengqin;CAI Yuexing;ZHAO Shengnan;TANG Sheng(Fangchenggang Meteorological Bureau,Fangchenggang,Guangxi 538001,China;Climate Center of Guangxi Zhuang Autonomous Region,Nanning 530022,China)

机构地区：[1]防城港市气象局,广西防城港538001 [2]广西壮族自治区气候中心,广西南宁530022

出　　处：《热带气象学报》2023年第4期433-442,共10页Journal of Tropical Meteorology

基　　金：广西气象科研计划项目(桂气科2023ZL04);防城港市科技局重点研发计划(防科AB21014037);广西台风与海洋预报服务创新团队项目共同资助。

摘　　要：利用NCEP FNL 1°×1°再分析、地面观测、FY-2G卫星和多普勒天气雷达等资料,对广西防城港沿海地区2020年6月16日出现的特大暴雨过程进行成因分析以及触发维持机制探讨。(1)此次极端降雨过程是一次暖区暴雨过程,降雨过程主要分为两个阶段,具有局地性强,雨势猛,强度大,降水难预报和突发性等特点。(2)暴雨在弱环流背景条件下发生,暴雨区有深厚的水汽和较强的不稳定能量,但天气尺度系统上升运动不深厚强度也不强,因而预报难度大。(3)初始对流在防城港南部近海海面触发,靠近海岸线时迅速发展加强,在防城港沿海地区演变成一个较大尺度的M_(β)CS,其西侧和南侧出现一连串强度45~55 dBZγ中尺度对流系统,不断经过暴雨区上空,形成列车效应最终导致极端降雨的发生。(4)天气尺度背景为北部湾近海海面出现对流提供了有利条件,低空急流的显著加强触发防城港市近海海面初始对流生成;不同性质下垫面的热力差异和M_(β)CS冷池出流造成防城港沿海地区出现中尺度低压及中尺度辐合线,致使对流在防城港沿海地区增强和长时间维持。(5)高温高湿环境中尺度扰动可能处于暖湿不稳定层结,微小的扰动也可以触发对流;预报服务中要利用多种新型高时空分辨率观测资料,及时判断分析沿海地区是否会出现海陆风或冷池出流等形成中尺度低压或辐合线。Using the NCEP FNL 1°×1°reanalysis data and the data from ground observation,FY2G satellite and doppler weather radar,the present study discussed the cause and the triggering and maintenance mechanism of the torrential rain occurred on June 16,2020 in the coastal areas of Fangchenggang in Guangxi Zhuang Autonomous Region.The results show that:(1)The extreme rainfall process is a warm-sector heavy rainfall.The rainfall process can be divided into two stages and it features highly concentrated heavy rainfall,strong intensity,and sudden precipitation,rendering it difficult to predict.(2)The rainstorm occurred under the background of weak circulation.The rainstorm area had deep water vapor and strong unstable energy,but the ascending motion of synoptic scale system was not deep nor strong,so it was difficult to forecast.(3)The initial convection was triggered in the coastal sea surface to the southern part of Fangchenggang,developed rapidly near the coastline,and evolved into a large-scale M_(β)CS in the coastal areas of Fangchenggang.A series of meso-γscale convective systems with intensity of 45~55 dBZ appeared on the west and south sides of M_(β)CS and they continuously passed through the heavy rain area,forming the train effect and eventually leading to extreme rainfall.(4)There were favorable conditions for convection in the offshore waters of Beibu Gulf.The significant strengthening of low-level jet triggered the initial convection in the offshore waters of Fangchenggang.Thermal difference of different underlying surfaces and M_(β)CS cold pool outflow cause mesoscale low pressure and mesoscale convergence line in the coastal areas of Fangchenggang,resulting in convective enhancement and longterm maintenance.(5)Mesoscale systems in high temperature and high humidity environments may be in warm and humid unstable stratification,and small disturbances may trigger convection.A variety of new high spatial and temporal resolution observational data should be used in forecast service to help analyze whether the

关 键 词：沿海特大暴雨 低空急流 中尺度辐合线 海陆风 触发维持机制 

分 类 号：P426.62[天文地球—大气科学及气象学]