长江下游梅雨期低涡统计分析  

The Statistical Analysis of Low Vortex During Meiyu Season in the Lower Reaches of the Yangtze

作　　者：杨引明[1] 谷文龙 赵锐磊 刘洁[1] 

机构地区：[1]上海市卫星遥感与测量应用中心,上海201100 [2]民航中南空管局气象中心,广州510405 [3]民航华东空管局气象中心,上海200335

出　　处：《应用气象学报》2010年第1期11-18,共8页Journal of Applied Meteorological Science

基　　金：国家自然科学基金项目(40505011和40405009);江苏省科技厅社会发展项目(BS2005055)共同资助

摘　　要：应用1998—2005年长江下游地区常规观测资料,结合卫星云图和中尺度数值模拟结果,对该时段发生在长江下游的局地生成中尺度低涡活动进行统计,并对低涡生成大尺度环境场及物理量参数进行合成诊断分析,为长江中下游地区梅雨期暴雨预报提供实际参考。结果表明:长江下游地区中尺度低涡主要形成于大别山山脉及山脉两侧的高能高湿的环境条件中,槽前的正涡度平流输送是低涡形成的必要条件之一。长江下游地区中尺度低涡一般存在于700 hPa以下的对流层低层,水平尺度普遍在400 km之内,形成后沿东北方向移动,在山东北部沿海入海,或沿东南方向移动在江苏南部到浙江北部沿海入海,在陆地上的生命期一般小于48 h,但70%以上的低涡都在长江下游地区触发中尺度对流系统发展而产生暴雨。暴雨区主要发生在低涡的南侧或东南侧,高低层急流配置、低层水汽输送和地形条件对低涡暴雨的触发具有重要作用。Local-generated mesoscale vortexes （LMVs） in the lower reaches of the Yangtze is one key factor to improve rainstorm forecast accuracy since they can efficiently trigger and organize mesoscale convective systems （MCSs）. There are many case studies focusing on the MCSs caused by LMVs, but in order to improve operational weather forecast ability during Meiyu season, the study about LMVs activities, structures and formative environment are necessary. Based on conventional weather data, satellite cloud images and numerical weather predictive outputs during Meiyu season of 1998-2005, the activities and structures of LMVs related to rainstorms in the lower reaches of the Yangtze are statistically analyzed, including the vortex generation, movement, life cycle, spatial range and related convective activities etc. Large scale environments and physical conditions are also synthetically analyzed. The result shows that LMVs in the lower reaches of Yangtze mainly generated around the Dabie Mountain area in Anhui Province. Typically, their horizontal scale changes from 100 km to 400 km, and most of them vary from 200 km to 300 km. Their vertical developing height usually changes from 1000 hPa to 700 hPa. LMVs moves mainly in two directions, one is northeast to as far as the Yellow Sea through north of Shandong Province, ant the other is southeastward towards the East China Sea through south of Jiangsu Province or north of Zhejiang Province. The life cycle of LMVs is less than 48 hours and it has no clear relations with their spatial scales. About 70 % LMVs trigger single MCS or series MCSs and can lead to rainstorms. Rainstorms mainly happen to the south or southeast of LMVs, where there are enough warm and moisture flow. LMVs generated at the bottom of upper level trough of 500 hPa are especially possible to cause rainstorms. Analysis of large scale environments and physical conditions show more than 90% of LMVs develops at the bottom or in front of upper level trough at 500 hPa. The positive vorticity advection in

关 键 词：中尺度低涡 梅雨锋 暴雨 合成分析 

分 类 号：P458.121.1[天文地球—大气科学及气象学]