摘要
利用探空资料、台站逐时观测资料和ERA5逐时再分析资料,以包含对流层高层气温特征的三维环流结构为切入点,系统分析了2022年8月17—18日引发青海省西宁市大通县山洪灾害的短时极端强降水的精细化特征。结果表明,强降水发生前,中国西北地区上空300 hPa存在明显暖异常,随着时间推移暖异常略向东南方向移动且强度逐渐增强,并在降水峰值时刻达到最强。在静力平衡的调控作用下,对流层高层暖异常上层出现位势高度正异常,下层出现位势高度负异常。与这种配置相对应,对流层高层出现反气旋式环流异常,为高层辐散创造了有利条件。随着暖异常移动增强,高空西风急流异常向东南移动增强。另外,对流层中、低层出现气旋式切变,低层偏东气流转变为气旋前部偏南气流,为降水地区低层暖湿条件增强、大气不稳定度增大创造了有利条件。这种三维环流结构不仅为强降水形成提供了有利的高、低层环流条件与水汽条件,还为不稳定能量的积蓄奠定了基础。同时,在大通县西北高、东南低的喇叭口地形影响下,低层偏南气流携带的丰富水汽在此处聚集,配合较强的不稳定能量,共同促成了此次短时极端强降水过程。
The three-dimensional circulation structure including the upper troposphere temperature characteristics is taken as a breakthrough point to analyze the impact of the evolution of the three-dimensional circulation structure on the formation and development of the short-term extremely heavy precipitation that caused flood disasters in Datong county of Xining city,Qinghai province during 17—18 August 2022.Hourly rain gauge records,sounding data and the ERA5 reanalysis dataset are used to analyze fine-scale characteristics of the short-term heavy rainfall that caused flood disasters in Datong county of Xining city,Qinghai province during 17—18 August 2022.The results show that before the heavy precipitation,there was an obvious warm anomaly at 300 hPa over the Northwest of China.As time went by,the warm anomaly slightly moved to the southeast and gradually intensified,reaching the strongest at the peak time of precipitation.Due to hydrostatic adjustment,positive(negative)geopotential height anomaly appeared above(below)the warm anomaly.Corresponding to this configuration,anticyclonic circulation anomalies occurred in the upper troposphere,creating a favorable condition for high-level divergence.Following the intensification of the warm anomaly movement,the westerly jet anomaly in upper levels moved to the southeast and strengthened.On the other hand,a cyclonic shear occurred in the middle and lower troposphere,and the easterly winds in the lower troposphere changed to southerly winds in the front of the cyclone,which created a favorable condition for the enhancement of warm and humid condition in the lower troposphere and the increase in atmospheric instability in the precipitation region.This three-dimensional circulation structure not only provided favorable circulation conditions in upper and lower levels as well as moisture condition for the formation of heavy precipitation,but also laid the foundation for the accumulation of unstable energy.At the same time,under the influence of the trumpet topography,which is high in the northwest and low in the southeast of Datong county,abundant water vapor carried by southerly winds in lower levels accumulated there,which,joined with strong unstable energy,contributed to the formation of the short-term extremely heavy precipitation.
作者
李泽雯
孙溦
宇如聪
LI Zewen;SUN Wei;YU Rucong(State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences,Beijing 100081,China;Institute of Tibetan Meteorology,Chinese Academy of Meteorological Sciences,Chengdu 610000,China;Department of Atmospheric Science,Yunnan University,Kunming 650091,China)
出处
《气象学报》
CAS
CSCD
北大核心
2024年第1期37-54,共18页
Acta Meteorologica Sinica
基金
北京市科技新星计划(Z211100002121100)
国家自然科学基金气象联合基金(U42204)。
关键词
青藏高原东北坡
短时强降水
三维环流结构
对流层高层温度
Northeast slope of Qinghai-Xizang plateau
Short-time heavy precipitation
Three-dimensional circulation structure
Upper tropospheric temperature
