引起陕北暴雨的西北涡特征分析  

Characteristic Analysis of Northwest Vortex Causing Torrential Rains in Northern Shaanxi

作　　者：蒋伊蓉 李晓利 刘慧敏 侯柯然 JIANG Yirong;LI Xiaoli;LIU Huimin;HOU Keran(Yulin Meteorological Bureau,Yulin 719000,Shaanxi,China)

机构地区：[1]陕西省榆林市气象局,陕西榆林719000

出　　处：《高原气象》2022年第3期646-654,共9页Plateau Meteorology

基　　金：秦岭和黄土高原生态环境气象重点实验室重点课题(2019Z-4);榆林市气象局科研项目(2019Y-5)。

摘　　要：利用2010-2019年地面自动站资料、探空资料和NCEP 1°×1°逐6 h再分析资料,对陕北地区西北涡暴雨个例进行统计和合成分析。结果表明:陕北暴雨有1/3以上是由西北涡引起,基本都发生在7-8月;西北涡多于青海西部生成,一般东移36~48 h后可造成陕北地区暴雨天气;陕北西北涡暴雨是在高空急流、高空槽、西太平洋副热带高压、700 hPa西北涡以及低层偏南偏东气流共同作用下产生的。对西北涡的结构研究表明,一方面700 hPa正涡度中心东南侧由于高层辐散、低层辐合的共同作用造成显著上升运动,这一区域正好对应暴雨落区;另一方面陕北处于高能高湿区中,并有偏南和偏东两条水汽通道将充沛的水汽输送至陕北并在此辐合上升,为暴雨的产生提供了有利的不稳定能量和水汽条件。The composite characteristics of northwest vortex that causes torrential rain in northern Shaanxi were analyzed statistically based on the in-situ observations from the automatic meteorological stations,ground-based sounding observations and reanalysis data from NECP.The main conclusions are as follows:one third of the torrential rains in northern Shaanxi can be attributed to the northwest vortex,which mainly occurred in July or August;the northwest vortex,mainly originated in the western Qinghai province,will probably trigger torrential rains in northern Shannxi 36 to 48 hours later;the torrential rains in the northern Shaanxi were closely related to the upper-level jet,the upper trough,the western Pacific subtropical high and 700 hPa northwest vortex.Indepth analysis of northwest vortex showed that the torrential rain area was just corresponding to the southeast of 700 hPa positive vorticity center,which was featured by the significant upward movement induced by high-level divergence and low-level convergence;the torrential rain in northern Shannxi was also beneficial from the favorably unstable and high humidity conditions,which were closely linked with the southern and eastern water vapor transportation.

关 键 词：西北涡 暴雨 高层辐散 低层辐合 水汽输送 

分 类 号：P458.121.1[天文地球—大气科学及气象学]