摘要
利用常规高空和地面气象观测数据、自动站气象观测数据及欧洲中期天气预报中心全球第五代大气再分析数据集(ERA5)等资料,对2023年8月22—25日百色市特大暴雨过程进行分析。结果表明:(1)此次过程具有一定的极端性。最大累计降雨量和日降雨量250 mm以上的特大暴雨出现在岑王老山东南侧。(2)强降雨发生在中、低层低涡受副热带高压阻挡在桂西停滞的形势下,湿层深厚、对流不稳定较强、抬升凝结高度和自由对流高度较低,适当的0℃层高度使暖云层较厚,在弱的垂直风切变下提高了降水效率。(3)在无低空急流的情况下,低层偏南风风速夜间加大,增强水汽输送和低层的辐合及垂直运动,导致强降水具有明显的夜雨特征。(4)低层东南风与岑王老山迎风坡耦合产生强烈上升运动,并在迎风坡以南形成垂直环流,利于产生对流;山脉的阻挡作用使雨带停滞,导致特大暴雨的发生。(5)数值模式降水产品的预报差异,无低空急流情况下水汽条件能否满足特大暴雨发生,地形的复杂机制等因素给此次过程的预报造成很大难度。
The extreme rainstorm process in Baise City on August 22—25,2023 was investigated using conventional upper air and ground observation data,automatic station observation data,and the ERA5 reanalysis data.The results showed that:(1)This process had a certain degree of extremity.The maximum accumulative rainfall and daily rainfall of more than 250 mm occured on the southeast side of the Cenwanglaoshan mountain.(2)Heavy rainfall occurred in the situation where the low vortexes in the middle and low layers of the troposphere were blocked by the subtropical high and stagnated in western Guangxi.Deep wet layer,stronger convective instability,lower lifting condensation level and free convection level,and the appropriate height of 0 ℃ layer resulted in a thicker warm clouds,which enhanced precipitation efficiency under weak vertical wind shear.(3)In the absence of low-level jet,the nocturnal enhancement of the low-level southerly winds strengthened the water vapor transport and the convergence at low levels and vertical movement,resulting in strong precipitation with obvious nocturnal rain characteristics.(4)The coupling of low-level southeasterly wind with the windward slope of Cenwanglaoshan produced a strong upward movement,and formed a vertical circulation in the south area of the windward slope,which was conducive to the generation of convection;the blocking effect of the mountain ranges made the rainbands stagnate,so extreme heavy rainstorm occurred.(5)The difference in the forecast of precipitation products in numerical models,whether the water vapor conditions can satisfy the occurrence of extreme rain in the absence of low-level jet,and the complex terrain mechanism caused great difficulties in forecasting this event.
作者
卢小丹
岑妍妍
黄开刚
刘国忠
LU Xiaodan;CEN Yanyan;HUANG Kaigang;LIU Guozhong(Baise Meteorological Bureau,Guangxi Baise 533000,China;Guangxi Meteorological Observatory,Nanning 530022,China)
出处
《气象研究与应用》
2023年第4期52-58,共7页
Journal of Meteorological Research and Application
基金
中国气象局气象能力提升联合研究专项(22NLTSY011)
广西气象科研计划项目(桂气科2023ZL01)。
关键词
特大暴雨
低涡
迎风坡
数值模式
extreme rainfall
low vortex
windward slope
numerical model
