黄土高原两次对流暴雨特征及成因异同分析  

Analysis on Characteristics and Formation Mechanisms ofTwo Convective Rainstorms over the Loess Plateau

作　　者：屈丽玮[1] 刘菊菊 赵强[1,2] 刘胜男 梁绵 潘留杰 Qu Liwei;Liu Juju;Zhao Qiang;Liu Shengnan;Liang Mian;Pan Liujie(Shaanxi Meteorological Observatory,Xi’an 710014,China;Key Laboratory of Eco-Environment and Meteorology of Qinling Mountains and Loess Plateau,Xi’an 710014,China)

机构地区：[1]陕西省气象台,西安710014 [2]秦岭和黄土高原生态环境气象重点实验室,西安710014

出　　处：《气象与环境科学》2025年第2期33-44,共12页Meteorological and Environmental Sciences

基　　金：秦岭和黄土高原生态环境气象重点实验室面上课题(2023G-1);中国气象局复盘总结专项(FPZJ2023-129);陕西省科技厅项目(2023-JC-YB-283);气象能力提升联合研究专项(24NLTSZ003)。

摘　　要：运用高空和地面加密自动气象站观测资料及欧洲中心ERA-5(0.25°×0.25°)再分析资料,对2019年7月黄土高原陕西北部连续发生的两次暴雨过程的对流环境条件、触发机制进行诊断分析,探讨锋生作用和暴雨动力因子的异同点。结果表明:(1)两次过程副高位置稳定,“7·21”过程暴雨出现在700 hPa暖式切变线南部暖区中,低层偏南暖湿输送持续增强,整层水汽辐合较强,强降水区自南向北移动,为暖区对流降水。“7·28”过程700 hPa形成冷式切变线,整层水汽辐合较弱,局地湿度条件更好,高层干冷空气自北向南侵入低层,形成比湿锋区,局地雨强较大,强降水区由北向南移动,为锋面对流降水。(2)两次过程CAPE均为狭长型,“7·21”过程抬升凝结高度较低,暖云厚度大。“7·28”过程CAPE值较大,整层能量条件更好,对流不稳定度更强。(3)两次过程的触发机制不同,西路弱冷空气入侵形成的地面中尺度辐合线触发“7·21”暴雨产生,过程以层积混合云降水回波为主,深厚持久的偏南急流的长时间维持,产生列车效应,导致累积雨量大。“7·28”过程中层较强锋生作用造成的强烈上升运动触发对流降水,配合气旋式辐合,形成东北—西南向带状积云回波,单点降水强度更大。(4)两次过程的对流涡度矢量及云水含量大值区与强降水落区的演变相对应,“7·21”过程表现为由西南向东北移动的趋势,“7·28”过程表现为自西北向东南移动的趋势。可见,对流涡度矢量在暖区对流降水和锋面对流降水中可以表征不同的强降水变化特征,在预报中有一定的参考价值。Based on the meteorological observation data,the ERA-5(0.25°×0.25°)reanalysis data of the European Centre for Medium-Range Weather Forecasts(ECMWF),the convective ambient conditions and trigger mechanism of two consecutive rainstorm processes over the Loess Plateau in northern Shaanxi Province in July 2019 are analyzed,and the similarities and differences of frontogenesis and dynamic factors of the rainstorms are discussed.The results are as follows:(1)The position of subtropical high was stable in both of the two rainstorm processes.The rainstorm on July 21 occurred in the warm zone in the south of the 700 hPa warm shear line.The transport of southerly warm and humid air in the lower layer was enhanced persistently,the water vapor convergence in the whole layer was strong,and the severe rainfall band moved from south to north,so the rainstorm belonged to warm-sector convective precipitation.During the July 28 rainstorm process,a cold shear line formed at 700 hPa,the water vapor convergence of the whole layer was weak,and the local humid conditions were even better.The high-level dry cold air intruded into the lower troposphere from north to south,forming a wet frontal zone.The local rain intensity was strong,and the severe rainfall band moved from north to south,so this was a frontal convective precipitation.(2)The CAPE of the two processes was of a narrow type.The lifting condensation height in the July 21 process was low and the thickness of warm clouds was large.The July 28 process had a higher CAPE value,a much better energy condition and even stronger convection instability.(3)The trigger mechanisms of the two processes were different.The meso-scale convergence line formed by the intrusion of weak cold air from west triggered the July 21 rainstorm.The rainstorm process was dominated by the stratified mixed cloud precipitation echo,and the long-term maintenance of deep and persistent southerly jet created the train effect,resulting in a large amount of accumulated rainfall.The strong upward motion caused

关 键 词：对流暴雨 锋生函数 对流涡度矢量 触发机制 

分 类 号：P458.121[天文地球—大气科学及气象学]