2022年6月12—13日江西中南部暴雨成因与预报误差分析

Study on Causes and Forecast Errors of Rainstorm inCentral and Southern Jiangxi During 12-13 June 2022

利用常规探空和地面观测站资料、ERA50.25°×0.25°再分析资料和ECMWF预报资料,对2022年6月12—13日江西中南部的暴雨过程进行分析。结果表明:(1)此次暴雨过程是在副热带高压和南亚高压稳定少动、西风槽携带冷空气南下的环流背景下,500 hPa高空槽、低层切变线、低空西南急流和地面静止锋共同作用造成的。(2)低层辐合、高层辐散产生深厚的垂直上升运动,为强降水的持续提供动力条件,低空暖湿西南急流输送的充足水汽,有利于江西中南部不稳定能量的积累。(3)EC暴雨落区预报偏北的主要原因是天气系统位置较实况偏北,700 hPa垂直速度大值区偏北、对流性降水预报偏弱和地形影响也是暴雨漏报的重要因素。(4)584 dagpm特征线的位置变化对此次暴雨落区向南订正有较好的指示意义。在暴雨预报中,不仅要考虑锋面大尺度降水,还要考虑暖区对流性降水,关注低层强动力辐合区域,结合中尺度数值模式产品,可以有效对主雨带位置和强度进行订正。

Based on the routine sounding and surface observation data,ERA50.25°×0.25°reanalysis data and ECMWF(abbreviated as EC,the same below)forecast products,the rainstorm process occurred in central and southern Jiangxi during 12-13 June 2022 was discussed.The results showed that the rainstorm was formed under the circulation backgrounds of steady subtropical high,south Asia high,and the westerly trough carrying cold air southward,and was triggered by the 500 hPa high-level trough,low-level shear line,low-level jet and stationary front.Convergence in low-level and divergence in high-level generating deep vertical upward movement provided dynamic conditions for continuous heavy precipitation.The southwest warm and wet airflow in low-level transported sufficient moisture,and was conducive to the accumulation of unstable energy in central and southern Jiangxi.The forecast of rainstorm area by EC was northerly mainly due to the forecasted weather system location more northerly.The northerly 700 hPa large vertical velocity area,the underestimate of convective precipitation and the effect of topography were important factors for the unreported rainstorm.The rainstorm area can be revised southward by the position change of 584 dagpm characteristic line to some extent.In the rainstorm forecast,the frontal large-scale precipitation,the warm-sector convective precipitation,and the strong dynamic convergence area in the low-level should be considered comprehensively,thus the position and intensity of the main rain belt can be effectively corrected combined with the mesoscale numerical model products.