塔克拉玛干沙漠南缘两次极端暴雨的气流模型与水汽输送特征  

Air Flow Model and Water Vapor Transport Characteristics of Two Extreme Rainstorms in the Southern Edge of Taklimakan Desert

作　　者：李如琦 李桉孛 李海花 李娜 LI Ruqi;LI Anbei;LI Haihua;LI Na(Xinjiang Meteorological Observatory,Urumqi 830002,China)

机构地区：[1]新疆气象台,新疆乌鲁木齐830002

出　　处：《沙漠与绿洲气象》2022年第6期1-10,共10页Desert and Oasis Meteorology

基　　金：新疆维吾尔自治区自然科学基金(2022D01D086);国家重点研发计划项目(2019YFC151050102);第二次青藏高原综合科学考察研究项目(2019QZKK010206)。

摘　　要：采用区域自动站逐小时降水观测数据、GPS/MET大气可降水量观测数据和NCEP/NCAR提供的FNL0.25°×0.25°分析数据,通过对比塔克拉玛干沙漠南缘和田地区2次落区接近、强度不同暴雨过程的环流和水汽特征,分析了影响极端暴雨产生的急流和水汽因子指标,结果表明:沙漠南缘暴雨时环流配置符合“三支气流”模型,高空急流、中层偏南风、低层辐合切变的强度与降水量正相关,当高层有极涡直接南伸至中亚发展而成的副热带大槽、中层有气旋前部的强偏南或西南气流、低层有偏东风急流明显西伸与西风急流形成强辐合时,有利于出现极端暴雨。沙漠南缘暴雨的水汽源地、输送路径、水汽含量、饱和层厚度与降水量相关,暴雨的水汽源地一般为欧洲和北冰洋,降水区水汽输入以中低层为主,低层比湿>6 g·kg^(-1),饱和层位于700 hPa以上;当中高层有来自阿拉伯海、孟加拉湾的由偏南风输送水汽的加入,低层比湿增加至8 g·kg^(-1)、饱和层扩展至750 h Pa以下时,可能出现极端暴雨。Using hourly precipitation data of regional automatic stations,GPS/MET atmospheric precipitable water data and the FNL 0.25°×0.25°analysis data of NCEP/NCAR,the circulation and vapor characteristics of two rainstorm processes in Hotan district on the southern edge of Taklimakan Desert(TD)are analyzed,and the influence factors of extreme rainstorm are revealed.The results show that the circulation configuration of rainstorm conforms to the“three branch air flow”model in the southern edge of TD,and the intensities of the upper jet,the mid-level southerly wind,and the lowlevel convergence shear are positively correlated with the precipitation.When the upper layer is a subtropical trough developed by the polar vortex directly extending to Central Asia,and the middle layer has a strong southerly or southwest airflow in the front of the cyclone,combined with the lower layer has a strong convergence between the easterly jet and the westerly jet,which is conducive to the occurrence of extreme rainfall.In the southern edge of TD,the water vapor source,transport path,vapor content and saturated layer thickness of rainstorm correlate with the precipitation,the vapor source of the rainstorm is generally from Europe and the Arctic Ocean,and the water vapor input of precipitation area mainly appear in the middle and low layers,with the specific humidity of the lower layer more than 6 g·kg^(-1)and the saturated layer above 700 hPa.When the water vapor in the middle and upper layers transported by the southerly wind from the Arabian Sea and the Bay of Bengal,the specific humidity of the lower layer reaches more than 8 g·kg^(-1)and the saturated layer expands below 750hPa,extreme rainstorms could occur.

关 键 词：极端暴雨 急流 水汽收支 气流模型 塔克拉玛干沙漠南缘 

分 类 号：P457[天文地球—大气科学及气象学]