娄山中小尺度地形影响下贵州遵义一次大暴雨过程分析
Analysis of a Heavy Rainstorm Process in Zunyi,Guizhou,under the Influence of Meso-small Scale Topography in Daloushan Mountains
黎凤丹 1刘红双 1肖蕾 1刘元美 2林雪飞 1骆海顺3
作者信息
- 1. 贵州省遵义市气象局,贵州 遵义 563000
- 2. 贵州省毕节市气象局,贵州 毕节 551700
- 3. 贵州省仁怀市气象局,贵州 遵义 564500
- 折叠
摘要
[目的]为探讨大娄山山脉地形在贵州遵义强降水过程中的动力、热力作用.[方法]利用地面加密自动气象站资料、探空资料、多普勒天气雷达资料及ERA5 再分析资料等,分析贵州遵义2023 年5 月20 日夜间一次局地强降水过程的降水特征、环流形势、物理量场及中尺度对流系统演变特征.[结果](1)过程发生在200 hPa分流辐散及中低层低槽、低涡切变辐合共同影响下,持续的上升运动配合整层大气高温高湿是该过程降水时间长、累积雨量大的重要原因.(2)大娄山地形使得850 hPa东南暖湿气流在迎风面聚集,导致θse及相对湿度梯度大值区沿着大娄山脉呈东北—西南向分布,使山脉东侧始终维持高能高湿的大气层结不稳定状态,为强降水的发生提供了有利条件.(3)持续的上升运动及暖湿气流输送使得2 个中尺度对流系统合并东移南压,列车效应明显,最终造成大暴雨.(4)源源不断的低层东南气流自大娄山山脉北部习水、桐梓之间的"V"型地形南侧翻山而过,由于娄山西支北端及金佛山地形阻挡,形成水汽通量大值中心,并在下风方形成水汽辐合带,产生水汽聚集效应,对流触发于地面辐合线北部与水汽通量散度梯度大值区重叠位置.[结论]娄山中小尺度地形对贵州遵义地区降水过程中的动热力条件有重要影响,为揭示娄山地形影响下此类强降水天气过程的成因提供了参考.
Abstract
Based on the data of automatic weather stations,radiosonde data,Doppler weather radar data and ERA5 reanalysis data,this paper analyzes the precipitation characteristics,circulation situation,physical quantity field and mesoscale convective system evolution of a local heavy precipitation process over the night of May 20,2023 in Zunyi,Guizhou Province.The dynamic and thermodynamic effects of the meso-small scale landforms in Daloushan Mountains during this process are discussed.The results show that:(1)This heavy rainfall process occurred under the influence of the 200 hPa divergence and the convergence of low trough and low vortex shear in the middle and lower atmospheres.The continuous upward movement and high temperature and high humidity in the whole layer are the important reasons for the long-lasting precipitation and large accumulated rainfall in the process.(2)The topography of Daloushan Mountains made the 850 hPa southeast warm and humid air gathere on the windward side,resulting in the θse and relative humidity gradient large-value area in the northeast-southwest distribution along the Daloushan Mountain range.There was a θse and relative humidity large-value area on the east side of the mountain range,that is,the unstable state of the stratification of high energy and high humidity was always maintained in the heavy rain area,providing favorable conditions for the occurrence of heavy precipitation.(3)The continuous upward movement and the transport of warm-humid air made the two mesoscale convective systems merge and move eastward and southward,causing obvious train effect and finally heavy rainfall.(4)The steady flow of low-level southeast air passed over the mountain from the south side of"V"shaped terrain between Xishui and Tongzi in the northern part of Daloushan Mountain range.Due to the blocking of the north end of western Daloushan Mountain range and the Jinfou Mountain,a large-value center of water vapor flux and a downwind water vapor convergence zone were formed,resulting in water vapor accumulation effect.Convection was triggered at the overlapping position between the northern part of the surface convergence line and the large-value area of the divergence gradient of water vapor flux.These analyses show that the meso-small scale topography of Daloushan Mountains has an important influence on the dynamic and thermodynamic conditions in the precipitation process in Zunyi,Guizhou Province,which could provide a reference for revealing the causes of such heavy precipitation weather processes under the influence of Daloushan Mountain terrain.
关键词
大娄山/中小尺度地形/地形作用/假相当位温/中尺度对流系统Key words
Dalou Mountains/meso-small scale topography/terrain effect/pseudo-equivalent potential temperature/mesoscale convective system引用本文复制引用
出版年
2024
NETL
NSTL
万方数据