贵州西部地区初夏一次暖区暴雨特征分析

Analysis of a Warm-Sector Heavy Rain in Early Summer in the West of Guizhou

文章对2020年6月1日发生在贵州西部地区的一次暖区暴雨过程进行暖区暴雨特征及物理量诊断分析,结果表明:暴雨发生前贵州西部处于高能、高湿区,低层以偏南暖湿气流为主,大气层结不稳定,不稳定能量积聚,地面辐合线触发中尺度对流单体发展,形成MCS云团,造成此次暴雨天气。MCS云团发展和成熟期在其西南侧云顶亮温梯度迅速增大,对应短时强降水特征明显,强回波单体集中在地面辐合线南侧呈线状排列,具有回波质心低的强降水特征。辐合线上南风的增强和地形阻挡、抬升作用对局地短时强降水有加强作用。通过对水汽、大气层结和动力条件等物理量特征诊断发现,暖区暴雨过程前低层孟加拉湾和南海的水汽输送通道建立,暖区暴雨过程中500 hPa以下大气层结处于弱不稳定状态,强辐合上升高度位于700 hPa附近,斜压涡度发展明显,低层湿位涡中心大值区对强降水中心位置的确定有一定指示意义。

This paper analyzes the characteristics and physical quantities of a heavy rainstorm in a warm area that occurred in western Guizhou on June 1,2020,the results show that:before the rainstorm,western Guizhou is in a high-energy and high-humidity area,and the lower layer is warm and wet to the south.The air flow is dominant,the atmosphere stratification is unstable,and there is a certain amount of unstable energy accumulation.The ground convergence line triggers the development of mesoscale convective monomers,forming MCS cloud clusters and causing this heavy rainstorm.During the development and maturity of the MCS cloud cluster,the cloud top brightness temperature gradient increases rapidly on the southwest side of the cloud,and the corresponding short-term heavy rainfall is obvious.The strong echo monomers are concentrated on the south side of the ground convergence line and arranged in a linear pattern,with the characteristics of heavy precipitation with a low echo center of mass.The strengthening of the southerly wind on the convergence line and the blocking and uplifting of the terrain have a strengthening effect on the local shortterm heavy rainfall.Through the diagnosis of physical characteristics such as water vapor,atmospheric stratification and dynamic conditions,it was found that the water vapor transport channels in the lower Bay of Bengal and the South China Sea were established before the process.During the process,the atmospheric stratification below 500 hPa was in a weakly unstable state,and the strong convergence rising height was near 700 hPa.The development of vorticity is obvious,and the large value area of the low-level wet potential vorticity center has a certain indicating significance for the determination of the location of the strong precipitation center.