眉山一次持续性强降雨天气过程分析

Analysis of a Continuous Heavy Rainfall in Meishan

利用常规气象观测资料、NCEP FNL再分析资料、FY-2卫星云图以及雷达资料,对2020年8月15~18日眉山一次持续性强降雨进行研究,结果表明:(1)高原涡和西南涡耦合是造成此次强降雨的影响系统,副热带高压强盛稳定形成阻塞,冷平流和中低层强水汽输送造成了持续性强降雨天气。(2)上冷下暖,大气层结不稳定;低层辐合,高层辐散促进对流的发展,强降雨过程上升运动显著增强,低层有强水汽辐合,有利于水汽汇集,为强降雨提供了重要的水汽条件。(3)强降雨发生在低亮温对流云团中,且对流云团有强烈的垂直上升运动,雷达回波强,并形成了急流轴,有利于强降雨的发生和持续。

Based on the conventional meteorological observation data,NCEP FNL reanalysis data,FY-2 satellite cloud image and radar data,a persistent heavy rainfall in Meishan from 15 to 18 August 2020 was studied.The results show that:(1)The coupling of plat-eau vortex and southwest vortex is the influencing system of the heavy rainfall,and the strong and stable subtropical high forms obstruc-tion,and the cold advection and the strong water vapor transport in the middle and low levels cause the persistent heavy rainfall weather.(2)Cold up and warm down,unstable atmospheric stratification.Low-level convergence and high-level divergence promote the develop-ment of convection.The ascending motion of heavy rainfall process is significantly enhanced.There is strong water vapor convergence in the low-level,which is beneficial to water vapor accumulation and provides important water vapor conditions for heavy rainfall.(3)Heavy rainfall occurs in low brightness temperature convective clouds,and convective clouds have strong vertical upward motion,strong radar echo,and formed a jet axis,which is conducive to the occurrence and continuation of heavy rainfall.