气象2026，Vol.52Issue(6)：641-656,16.DOI:10.7519/j.issn.1000-0526.2026.051303
北京"25·7"极端暴雨时空特征及形成机制分析
Spatio-Temporal Characteristics and Formation Mechanisms of the July 2025 Extreme Torrential Rain in Beijing
摘要
Abstract
From 23 to 29 July 2025,extreme torrential rain occurred in Beijing.Based on multi-source ob-servation data,ERA5 reanalysis data,RISE and RMAPS-NOW high-resolution grid analysis data,this pa-per analyzes the characteristics of rainfall stages,the spatio-temporal features and causes of this event.The results show that the July 2025 extreme torrential rain occurred under a stable circulation background where the subtropical high was significantly westward and northward and stronger than usual,with active tropical systems on its southern side.The lower atmosphere had warm anomalies,with a positive water vapor flux anomaly at 925 hPa and a significantly enhanced water vapor convergence zone in northern and eastern Beijing,creating conditions of high temperature,high humidity and high CAPE.This rainfall event was featured with long duration,much more accumulated precipitation,nocturnal occurrence,locali-zation and extremity.According to the daily evolution of precipitation,the whole event is divided into four stages,corresponding to the swing of the 588 dagpm contour position of the subtropical high.Extreme torrential rain occurred in Stage 2 and Stage 3,concentrated in the northern mountainous areas of Beijing,featuring a"weak overall but strong locally"pattern,and also accompanied by extreme short-time heavy rainfall.The focus analysis on this two stages indicates that,the radar echoes in Stage 2 showed obvious backward triggering and"train effect"characteristics,lasting 4-5 h with torrential rain occurring at alti-tudes of 200-600 m.However,in Stage 3 there were continuous generation and dissipation of convection within banded echoes,lasting more than ten hours,with the occurrence of torrential rain mainly below the 300 m altitude.Further analysis on the causes shows that both Stage 2 and Stage 3 had favorable dynamic and topographic conditions,including the exit area of the mesoscale low-level jet,the convergence of southerly and southeasterly winds in the boundary layer,as well as the horn-shaped terrain and windward slopes of the mountains.The difference between two stages is that it was warm-sector torrential rain in the Stage 2,during which the exit area of southern boundary-layer jet was in the northern shallow mountains,the low-level convergence along the mountains was conducive to continuous triggering of convection,and the"train effect"caused the occurrence of extreme torrential rain.While the Stage 3 was influenced by a weak cold air and was related to dynamic convergence on the southern side of a shear line and a mesoscale low vortex.Accordingly,the conceptual model of the July 2025 extreme torrential rain is established.关键词
极端暴雨/副热带高压/中尺度急流/列车效应/地形Key words
extreme torrential rain/subtropical high/mesoscale jet/train effect/terrain分类
天文与地球科学引用本文复制引用
雷蕾,邢楠,李桑,李京南,张琳娜,吴宏议,刘瑞婷,宋林烨..北京"25·7"极端暴雨时空特征及形成机制分析[J].气象,2026,52(6):641-656,16.基金项目
灾害天气科学与技术全国重点实验室开放课题(2025KFA02)、国家自然科学基金面上项目(42375020)、中国气象局复盘总结专项(FPZJ2026-002)、中国气象局"首都气象精准预报"青年创新团队(CMA2023QN10)和中国气象局创新发展专项(CXFZ2023J018)共同资助 （2025KFA02）
