一次西藏大范围强降水的诊断分析  

An Analysis of the Largescale Heavy Precipitation Process in Tibet by the Bay of Bengal Storm

作　　者：旦增冉珍 卓玛 次仁拉姆 普布扎西 德吉白珍 DAN Zeng-ran-zhen(Tibet Autonomous Region Meteorological Station,Lhasa,Tibet 850000)

机构地区：[1]西藏自治区气象台,西藏拉萨850000

出　　处：《农业灾害研究》2021年第1期20-24,共5页Journal of Agricultural Catastrophology

基　　金：中国气象局预报员专项项目(CMAYBY2020-128);第二次青藏高原综合科学考察研究项目“西藏重要天气过程监测、分析与研究”(2019QZKK010207)。

摘　　要：利用常规观测资料、NCEP再分析资料以及卫星TBB资料,对2020年5月20-21日西藏强降水过程的环流背景、物理量以及其中尺度特征等进行了分析。得出以下结论:(1)此次西藏大范围的强降水天气过程中中高纬地区为两槽一脊型,巴尔喀什湖附近不断有低槽分裂冷空气南下影响高原,500 hPa上的高原槽与高低空急流的配置,是此次强降水过程的主要影响系统。(2)孟加拉湾热带风暴"安攀"登陆后外围云系不断上高原,强降水区的高湿区明显,500 hPa相对湿度≥95%、比湿达到5 g·kg^(-1)以上,为强降雨天气提供了有利的水汽条件。(3)CAPE值较高,达到1000 J/kg,CIN值较低,对流能量充足,有利于不稳定能量释放,配合强的垂直速度上升中心,中心值为-1 Pa·s^(-1)为降雨天气提供了有利的上升运动,是此次降水过程的主要动力条件;(4)在26°N~30°N之间高空有一明显的假相当位温能量锋区,且随纬度的增高而向高空倾斜,为强降水天气提供了热力条件;(5)卫星云图TBB分布:反映出降雨期间有中小尺度对流云团配合,孟加拉湾风暴"安攀"最强云团中心最大TBB值达-80℃,强降水期间日喀则南部、山南南部和林芝南部最强对流云团的云顶亮温为-60℃左右,对流云团的生成为短时强降水提供了中尺度系统。This paper analyzes the circulation background,physical quantity and scale characteristics of heavy precipitation process in tibet from may 20 to 21,2020 using micaps conventional observation data,ground precipitation data and satellite TBB data.(1)The middle and high latitudes are two troughs and one ridge in the large-scale heavy precipitation in Tibet,and the low troughs near Lake Balca continuously split cold air down the upper plateau.The plateau trough on hPa 500 is the main influence system of the heavy precipitation process.(2)During the rainfall period,the high humidity area of 500 hPa≥90%relative humidity is obvious,and the strong vertical velocity rising center-1 Pa·s^(-1) provides favorable rising motion for rainfall weather.From 200 hPa and 500 wind field analysis,the configuration of high and low air jet is the main dynamic condition for strong precipitation in the south;(3)Satellite cloud map TBB distribution:reflecting the cooperation of mesoscale systems during rainfall,the maximum TBB value of the centre of the strongest cloud cluster of the Bay of Bengal storm"Anpan"reaches-80℃,and the cloud top bright temperature of the strongest convective cloud cluster in southern Xigaze,southern Shannan and southern Linzhi is about-60℃during heavy precipitation.

关 键 词：西藏 孟湾热带风暴“安攀” 物理量诊断 TBB 

分 类 号：S161[农业科学—农业气象学]