摘要
利用气象观测资料、NCEP/NCAR 1°×1°×再分析以及GDAS等资料,对2021年10月2—7日山西持续性强降水天气过程进行分析。结果表明:稳定的乌拉尔山低槽后部冷空气扩散,中纬度短波槽东移,与副热带高压外围西南暖湿气流持续交汇,高低空急流耦合形成强烈上升运动,低层切变线和地面辐合线稳定维持,及低层水汽不断输送并形成辐合,为持续性强降水的发生发展提供有利的动力和水汽条件。强降水过程分为对流性降水和稳定性降水2个阶段,2个阶段水汽输送通道的源地、路径、高度存在明显差异,但水汽输送贡献率均为对流层中低层山西南侧的水汽输送占主导地位。降水开始前,对流层中上层存在对称不稳定,大气可降水量明显跃增;对流性降水阶段,干空气不断入侵,对流不稳定快速建立与释放,对流层中低层水汽辐合区与强上升气流配合,导致山西出现强对流天气。地形的阻挡、抬升及地形收缩作用对局地极端强降水有增幅作用。
The persistent heavy rainstorm that occurred in Shanxi province from October 2th to 7th,2021 was analyzed based on meteorological observation data,NCEP/NCAR 1°×1°×reanalysis data,and GDAS data.The findings reveal that the cold air behind the stable Ural low trough and mid-latitude short wave trough moved southward and interacted with the warm moist air outside the subtropical high in southwestern China.Simultaneously,a strong upward movement coupled with high and low-level jets maintained the stability of the low-level shear line and surface convergence line,facilitating continuous transport of low-level water vapor which converged to provide favorable conditions for the occurrence and development of persistent heavy rainfall.The heavy precipitation process can be divided into two stages:convective precipitation and stable precipitation.Although there were significant differences in terms of water vapor source,path,and height between the two stages,water vapor transport from southern Shanxi province dominated as a major contributor throughout both stages.Prior to precipitation onset,symmetric instability was observed in the upper troposphere along with a notable increase in precipitable water content.During the convective precipitation stage,frequent intrusion of dry air established rapid convective instability while cooperation between convergence areas of middle-to-lower tropospheric water vapor and strong updrafts resulted in intense convective weather over Shanxi province.Additionally,local extreme heavy precipitation was further enhanced by blocking effects as well as terrain-induced uplift and contraction.
作者
乔钰
赵桂香
王妍
QIAO Yu;ZHAO Guixiang;WANG Yan(Shanxi Meteorological Observatory,Taiyuan 030006,China;Yangquan Meteorological Observatory,Yangquan 045000,China)
出处
《沙漠与绿洲气象》
2024年第4期59-67,共9页
Desert and Oasis Meteorology
基金
国家自然科学基金面上项目(41475050)
山西省气象局面上项目(SXKMSTQ20226306)。
关键词
阶段性降水
环流形势
水汽输送
动力抬升
periodic precipitation
circulation situation
water vapor transport
dynamic uplift
