华北平原一次大气涌及其对夜间对流的影响  

An Atmospheric Bore in North China Plain and Its Impact on Nocturnal Convection

作　　者：姚安琪 陈起英[2,3] 华维 Yao Anqi;Chen Qiying;Hua Wei(School of Atmospheric Sciences,Chengdu University of Information Technology,Chengdu 610225;CMA Earth System Modeling and Prediction Center,Beijing 100081;State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences,Beijing 100081)

机构地区：[1]成都信息工程大学大气科学学院,成都610225 [2]中国气象局地球系统数值预报中心,北京100081 [3]中国气象科学研究院灾害天气国家重点实验室,北京100081

出　　处：《应用气象学报》2025年第2期178-189,共12页Journal of Applied Meteorological Science

基　　金：国家自然科学基金气象联合基金重点支持项目(U2342226);国家自然科学基金重大项目(42090032);国家自然科学基金项目(41375107);中国气象局气象能力提升联合研究专项重点项目(22NLTSZ006)。

摘　　要：大气涌(一种特殊的大振幅重力波)已被证明对夜间中尺度对流系统的触发和维持具有重要作用。为探究大气涌对华北平原夜间对流的潜在作用,深入了解大气涌的产生及影响机制,对2022年6月17—18日一次起源于太行山北部并向东传播至华北平原东部的对流过程进行观测分析,并使用CMA-MESO业务模式(水平分辨率为1km)进行数值模拟和诊断。结果表明:对流产生的密度流侵入夜间稳定边界层触发大气涌。根据线性波理论,由稳定度项和风速曲率项共同定义的斯科勒参数表征了大气对重力波的捕获能力。研究过程中,夜间低空急流产生的垂直切变使斯科勒参数在500~1100m高度范围内随高度递减,这一变化表明该高度层形成有利于大气涌能量集中和水平传播的波导结构,有利于大气涌的维持和传播,使其持续约3h。大气涌经过后,夜间大气稳定度降低,对流有效位能约增加270J·kg^(-1),对流抑制能量约降低100J·kg^(-1)。大气涌比对流系统的传播速度更快,通过垂直抬升减弱逆温覆盖,将底层水汽向上输送,触发了新的对流单体,新对流单体与原对流系统合并,使此次夜间对流增强并维持。Atmospheric bores(a special type of large-amplitude gravity wave)are generated when density currents intrude into the nocturnal stable boundary layer,and they are proven to play a significant role in triggering and maintaining nocturnal mesoscale convective systems.Potential role of atmospheric bores in nocturnal convection over North China Plain is investigated through looking into the generation and impact mechanisms.Atmospheric bores are identified using surface station data and Doppler radar base data at Weifang Station.A nocturnal convection event originating in the northern Taihang Mountains and propagating eastward to the eastern North China Plain on 17 June 2022,is diagnosed and simulated using CMA-MESO operational model(1 km).Observational analysis reveals that convection-generated density currents intrude into the nocturnal stable boundary layer,triggering nonundular bore,and as the environmental flow regime transitions from supercritical to subcritical state,large-amplitude internal gravity waves are generated and trapped,transforming into undular bore.CMA-MESO operational model successfully simulates the evolution of the entire convective system and the southward-propagating atmospheric bore ahead of the convection,as well as the convective cells triggered by the atmospheric bore on the southern side of the convection.The bore propagates at approximately 13.2 m·s-1,which is typical for gravity wave propagation speed and consistent with observations.The depth ration between near-surface light fluid and density current and Froude number of the selected profiles indicate that convection-generated density current intrudes into the nocturnal stable boundary layer,causing a complete blocking flow regime that triggers a type C bore ahead of the convective system.As the density current weakens,the bore gradually transitions into a type B bore.According to linear wave theory,Scorer parameter,defined by both stability and wind speed curvature terms,characterizes the atmosphere's ability to trap gravity waves.T

关 键 词：华北平原 夜间对流 大气涌 CMA-MESO 

分 类 号：G63[文化科学—教育学]