青藏高原东坡地形对影响云南降水的高原涡的作用机理  

Action Mechanism of Tibetan Plateau’s Eastern Slope Topography on the PLV Affecting Yunnan Precipitation

作　　者：何钰[1,2] 朱莉 李国平[3] 谢家旭 马文倩[1,2] 陶丽 张万诚 HE Yu;ZHU Li;LI Guoping;XIE Jiaxu;MA Wenqian;TAO Li;ZHANG Wanchen(Yunnan Mereorological Observatory,Kunming 650034,Yunnan,China;Research Center for Disastrous Weather over Hengduan Mountains&Low-Latitude Plateau,China Meteorological Administration,Kunming 650034,Yunnan,China;College of Atmospheric Sciences,Chengdu University of Information Technology,Chengdu 610225,Sichuan,China;Wuhan Regional Climate Center,Wuhan 400070,Hubei,China;Sichuan Province Meteorological Service Center,Chengdu 610225,Sichuan,China;Meteorological Institute of Yunnan,Kunming 650034,Yunnan,China)

机构地区：[1]云南省气象台,云南昆明650034 [2]中国气象局横断山区(低纬高原)灾害性天气研究中心,云南昆明650034 [3]成都信息工程大学大气科学学院,四川成都610225 [4]武汉区域气候中心,湖北武汉400070 [5]四川省气象服务中心,四川成都610225 [6]云南省气象科学研究所,云南昆明650034

出　　处：《高原气象》2024年第1期42-58,共17页Plateau Meteorology

基　　金：国家自然科学基金项目(41765003,42065006,42075013);云南省气象局自筹科研项目(CS202203)。

摘　　要：利用常规观测资料、FNL分析资料及经质控后的自动站小时降水数据,诊断分析了青藏高原东坡地形在2017年7月2-3日高原涡影响云南降水过程中的作用,并利用数值模式WRFv4.0对此次过程进行了地形敏感性试验。结果表明:高原涡是此次云南强降水的重要影响系统;低涡中心及附近区域中高层维持暖心结构,并呈现显著的上升、下沉运动交替的分布;过程累积雨量分布表现为两条明显的与山脉走向平行的西北-东南向雨带,且具有强弱交错的分布特征,强降水集中出现在午后至傍晚及前半夜两个时段内,中心均位于地形边坡,并随着低涡向下游传播;南亚高压、西北辐散气流、西太平洋副热带高压及滇缅高压为低涡的东移发展提供了有利的高空环流场,500 hPa正涡度及700 hPa水汽通量辐合中心对强降水落区具有较好指示意义;低涡降水期间存在β中尺度重力波,波动由青藏高原东坡地形激发,沿着300~200 hPa的气层传播,高空的非地转平衡运动及垂直风切变为重力波的发展及传播提供了有利条件,重力波先于低涡及降水向下游方向移动及发展,波脊处对应上升运动及辐散中心,波槽处对应下沉运动及辐合中心,强降水及波脊均位于低涡西南侧强辐合上升运动区;地形高度降低后,其机械阻挡抬升作用减弱,重力波和高原低涡消失,雨带强度及空间分布特征发生显著改变。高原东坡地形对高原涡的形成和发展,以及高原涡影响下的云南降水具有重要作用。Using radiosonde and ground mapping data from conventional observations,FNL analysis data(1°×1°)and quality controlled hourly precipitation data of Yunnan regional automatic station,diagnosed the function of the Qinghai-Xizang Plateau’s eastern slope topography in the PLV(plateau vortex)affected precipitation in Yunnan during 2-3 July 2017.While the latest WRFv4.0 numerical model is used to conduct the topographic sensitivity test of this process.The results show that PLV which generated in the Yajiang region of Sichuan province(NO.C1735)is an important system influenced on this heavy rainfall in Yunnan;This low-vortex system maintain warm core structure in the middle and high altitude during the process period,corresponding with remarkable alternately distribution of ascending and descending movements;Distribution of process accumulated rainfall present two obvious NW-SE rain belts parallel to the mountain trend and the precipitation on the rain belt have intensity interlaced fluctuation characteristics;The heavy rainfall mainly occurred within two periods:one from afternoon to evening and other at the first half of the night,and all located besides the terrain slope(the east and south slopes),especially in areas with steep terrain,large slopes,and trumpet-shaped topography,and then propagates downstream alone with the PLV;The South Asian High,northwest divergent airflow,Western Pacific subtropical high and Yunnan-Myanmar high provides favorable upper flow field for the eastward movement and development of the PLV,besides the position of 500 hPa positive vorticity and 700 hPa water vapor flux convergence can well indicates the heavy rainfall area;There existβ-mesoscale gravity wave during the period of precipitation,which stimulated by the Qinghai-Xizang Plateau’s eastern slope,and propagate between 300~200 hPa;Non geostrophic equilibrium motion and vertical wind shear at high-altitude are beneficial to the occurrence and propagation of gravity wave;The gravity wave propagate downstream before the PLV an

关 键 词：青藏高原东坡 高原涡 重力波 地形敏感性试验 

分 类 号：P458.2[天文地球—大气科学及气象学]