四川盆地西部两次极端暴雨的广义湿位涡诊断分析  

Analysis of Generalized Wet Potential Vorticity in Two Extreme Rainstorms in the Western Sichuan Basin

作　　者：郭云云 邓莲堂 蒋伊蓉[5] GUO Yunyun;DENG Liantang;JIANG Yirong(Sichuan Provincial Meteorological Observatory,Chengdu 610072,China;Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province,Chengdu 610072,China;National Meteorological Centre,Beijing 100081,China;Nu-merical Weather Prediction Centre of CMA,Beijing 100081,China;Yulin Meteorological Bureau,Yulin 719000,China)

机构地区：[1]四川省气象台,成都610072 [2]高原与盆地暴雨旱涝灾害四川省重点实验室,成都610072 [3]国家气象中心,北京100081 [4]中国气象局数值预报中心,北京100081 [5]陕西省榆林市气象局,榆林719000

出　　处：《高原山地气象研究》2022年第1期45-50,共6页Plateau and Mountain Meteorology Research

基　　金：国家自然科学基金项目(41275103)。

摘　　要：利用ERA50.25°×0.25°再分析资料、MICAPS4的常规资料以及四川加密自动站逐时降水观测资料,对2020年8月11~13日和15~18日发生在四川盆地西部的两次极端暴雨过程的广义位温和广义湿位涡进行诊断分析。结果表明:两次暴雨过程均属于500 hPa“东高西低”型暴雨,中高层南亚高压、高空急流、西风槽和低层切变线、低涡等天气系统是两次暴雨有利的动力条件,低空急流则是暴雨区良好的水汽条件。两次过程暴雨区上空均存在强广义位温梯度区和强广义湿位涡异常区,“8.11”暴雨出现高度为800~900 hPa,“8.15”暴雨出现高度为700~800 hPa,这种分布与低层相对湿度含量密切相关,即相对湿度越高,广义位温垂直梯度越强,广义湿位涡异常区中心值越高。两次暴雨的强降水站点广义位温和广义湿位涡的时空演变和降水的时间演变均有较好的对应关系,但广义湿位涡强度与小时雨强并不存在明显的正相关关系。Based on the 0.25°×0.25°reanalysis data from ERA5,the conventional data from MICAPS4 and the hourly precipitation observation data from the Sichuan Automatic Stations,the generalized potential temperature(θ*) and generalized wet potential vorticity(GMPV)of the two extreme rainstorm processes occurred in the western Sichuan Basin on 11~13 and 15~18 August 2020 were diagnosed and analyzed.The results indicate that:The two rainstorm were‘east high and west low’in the 500hPa.The South Asia high pressure,high altitude jet,west wind trough,low-level shear line and vortex were favorable dynamic conditions for the two rainstorms.Low-level jet was a good water vapor condition in rainstorm area.There were θ* gradient area and GMPV anomaly area over the two rainstorm areas,the warning height of'8.11'was 800~900hPa,and the height of'8.15'was 700~800hPa.This distribution was closely related to the low-level relative humidity(rh)content,that is,the higher the rh,the stronger the vertical gradient of θ* and value of the abnormal area of GMPV.The temporal and spatial evolution of θ* and GMPV had a good correspondence with the temporal evolution of heavy precipitation stations.However,there was no significant positive correlation between the GMPV intensity and hourly rainfall intensity.

关 键 词：广义位温 广义湿位涡 极端暴雨 

分 类 号：P458.3[天文地球—大气科学及气象学]