内蒙古河套地区一次大暴雨天气过程中尺度分析

Mesoscale Analysis of a Heavy Rainstorm Process in Hetao Region of Inner Mongolia

文章利用常规气象观测资料,多普勒雷达、卫星云图及ERA5再分析资料,分析了2022年8月1—2日河套地区的一次大暴雨过程。结果表明:副热带高压稳定维持、850 h Pa暖式切变和地面低压倒槽为本次暴雨天气过程提供有利的大尺度环流背景。低空急流、低层的水汽强辐合,低层辐合、高层辐散的耦合配置,θse梯度大值区,“上干下湿”的不稳定层结,较强的对流有效位能是产生强对流天气的有利环境条件。MCS移动速度缓慢,“列车效应”是造成局地极端大暴雨发生的主要原因。中尺度对流系统的主要触发机制是地面辐合线,还与乌拉山的地形作用密不可分。

Using conventional meteorological observation data,Doppler radar data,satellite cloud images and ERA5 reanalysis data,a warm rainstorm process in Hetao region during August 1-2,2022 is analyzed.The results show that the stable maintenance of subtropical high,850 h Pa warm shear and surface low overbearing trough provide favorable large-scale circulation background for this weather process.The favorable environmental conditions for strong convective weather are low level jet stream,strong convergence of water vapor at low level,coupling configuration of low level convergence and high level divergence,large value area ofΔθ_(se)gradient,unstable stratification of“dry above and wet below”and strong effective potential energy of convection.MCS moves slowly and the“train effect”is the main reason for the occurrence of local extreme.The main trigger mechanism of the mesoscale convective system is the surface convergence line,which is also closely related to the topography of the Wula Mountains.