山东半岛一次冷涡背景下暖区暴雨漏报成因分析

Analysis of the Causes of Underreporting a Heavy Rain in Warm Sector in Shandong Peninsula under the Background of a Cold Vortex

摘要: 利用常规观测数据和ERA5 (Fifth Generation of ECMWF Reanalysis) 0.25˚ × 0.25˚再分析资料，对2022年6月14日山东半岛一次预报失败的局地大暴雨过程进行了综合诊断分析。结果表明：1) 暴雨发生在冷涡槽前暖湿气流中，低空急流的两次建立为暴雨提供了持续充足的水汽和不稳定能量条件；2) 低层暖湿切变线、地面海陆风中尺度辐合线是触发对流的主要机制，沿岸热力差异和山地地形强迫作用使局地对流强度增强；3) 雨带分布与两个阶段的中尺度对流系统(MCS)发展演变有关，沿岸对流系统合并与列车效应造成了局地大暴雨；4) 降水发生前，数值预报模式对低空急流和地面中尺度辐合线预报较差，预报员对于暖区降水的认识不足是暴雨漏报的主要原因。

Abstract: Using conventional observation data and ERA (Fifth Generation of ECMWF Reanalysis) 0.25˚ × 0.25˚ reanalysis data, on the Shandong Peninsula of June 14, 2022, a comprehensive diagnosis was made for the cause of a local heavy rainstorm where the forecast failed. The results show that: 1) the rainstorm occurred in the warm and humid air flow in front of the cold vortex trough, and the two establishment of the low-level jet provided continuous and sufficient water vapor and unstable energy conditions for the rainstorm; 2) The low-level warm and humid shear line and the mesoscale convergence line of the surface sea-land breeze are the main mechanisms that trigger convection. The coastal thermal differences and mountain terrain forcing enhance the intensity of local convection; 3) The distribution of rain belt is related to the development and evolution of mesoscale convective system (MCS) in the two stages. The combination of coastal convective systems and the train effect caused local heavy rainstorm; 4) Before the occurrence of precipitation, the poor prediction of the low-level jet and the surface mesoscale convergence line by the numerical prediction model, and the lack of understanding of the precipitation in warm sector by the forecasters, are the main reasons for the failure of rainstorm forecasting.