陕北两次不同强度的区域性暴雨过程特征对比  

Comparative Analysis of Characteristics of Two Regional Rainstorm Processes with Different Intensities in Northern Shaanxi

作　　者：刘胜男 屈丽玮[1] 张蔚然 赵强[1] LIU Shengnan;QU Liwei;ZHANG Weiran;ZHAO Qiang(Shaanxi Provincial Meteorological Observatory,Xi’an 710014,China)

机构地区：[1]陕西省气象台,西安710014

出　　处：《高原山地气象研究》2024年第3期48-57,共10页Plateau and Mountain Meteorology Research

基　　金：陕西省自然科学基础研究计划项目(2023-JC-QN-0376);中国气象局创新发展专项(CXFZ2023J031);灾害天气国家重点实验室开放基金(2022LASW-B20)。

摘　　要：利用ERA-5逐小时再分析资料、雷达资料、地面加密站和常规探空资料,对2019年7月21日和2020年8月4日陕北地区两次不同强度的暴雨过程进行对比分析。结果表明:(1)强降水的持续性是造成“0804”过程累计降水量大于“0721”过程的直接原因。(2)“0804”过程中,陕北上空层-积混合云回波在夜间的走向和移动方向一致,“列车效应”使低质心暖云降水长时间维持。(3)两次过程降水强度的区别与高低空急流、低涡路径和水汽有密切联系。与“0721”过程相比,“0804”过程中200 hPa高空急流更为稳定,700 hPa西南急流强度更大,强雨带更靠近低涡中心,动力抬升和水汽辐合均偏强。(4)两次过程对流触发机制存在差异,“0804”过程前期地面较强的偏东风更有利于地形抬升。Using ERA-5 hourly reanalysis data,radar data,conventional sounding data and intensive automatic stations data,two different heavy rains in northern Shaanxi on July 21,2019 and August 4,2020 were compared and analyzed.It shows that(1)The persistence of heavy precipitation was the direct reason why the accumulated precipitation in“0804”process was greater than that in“0721”process.(2)Composite radar reflectivity showed a ENE-WSW oriented stratocumulus echo moved eastward across northern Shaanxi in the process of“0804”at night which led to the quasi-stationary rainbands.(3)The coupling of upper and low level jet,the path of low vortex and water vapor transportation played important roles in causing the difference of intensity of the two precipitation processes.The upper level jet at 200 hPa in the process of“0804”stayed stable and the intensity of low level jet at 700 hPa was stronger than that in the process of“0721”.The torrential rain area in the process of“0804”was closer to the center of the vortex which provided adequate water and water vapor convergence lifts.(4)The triggering mechanism of convection in two processes is different,and the strong easterly wind on the ground in the"0804"was more conducive to topographic uplift.

关 键 词：暴雨 陕北 高低空急流 低涡 水汽输送 

分 类 号：P458.121.1[天文地球—大气科学及气象学]