热带气象学报2025，Vol.41Issue(1)：41-54,14.DOI:10.16032/j.issn.1004-4965.2025.003
四川盆地西部不同形态地形下一次暖区特大暴雨的两阶段比较分析
Comparative Analysis of Two Stages of a Warm-sector Torrential Rainfall Under Different Terrains in the Western Sichuan Basin
摘要
Abstract
The topography along Longmen Mountain,Sichuan Province,is complex,featuring different orientations of trumpet-shaped and windward slope topography.This region experiences numerous mountain rainstorms,yet the detailed study of warm-sector rainstorms in this area and the application of the complex topography in operational forecasting and disaster prevention and reduction are still meager.Using ERA5 reanalysis data,intensive ground observation data,and real-time precipitation data,this study conducted a comparative analysis of the water vapor transport,topographic uplift,and physical mechanisms of two stages of a warm-sector torrential rainfall that occurred on August 11,2020,under different terrains.It revealed the evolution of water vapor and dynamic structures and the triggering and sustaining mechanisms of warm-sector rainstorms under the influence of synoptic forcing and special topographic conditions.The results were as follows:(1)The two stages of the warm-sector rainstorm corresponded to two rainstorm centers.The Lushan rainstorm in Ya'an occurred under the influence of southeast winds,with no significant system at 500 hPa and no jet stream at lower levels.The rainstorm in Shigu Town,Deyang,occurred on the windward slope of Longmen Mountain under the influence of the westward extension of the 500 hPa Western Pacific Subtropical High,the approaching trough,and the presence of a jet stream at lower levels.The Lushan rainstorm was notably nocturnal,while the Shigu rainstorm mainly occurred during the day.The duration of convective precipitation in Shigu was nearly twice as long as that in Lushan,yet the peak hourly precipitation was only half of that in Lushan.(2)The blocking effect of the large plateau terrain,the uplift of the windward slope,and the lateral convergence of the trumpet-shaped terrain and canyon terrain facilitated water vapor convergence in Lushan.Due to the strengthening of the low-level jet at 850 hPa,the topographic blocking of Longmen Mountain and the lifting of the windward slope,water vapor was abundant over Shigu.The convergence intensity of water vapor flux divergence in the Lushan rainstorm was significantly smaller than that in the Shigu rainstorm,but the convergence layer height was higher.(3)The overall rate of topographic uplift surpassed the local rate,with its peak occurring 1 hour earlier than the peak of hourly rainfall intensity,providing a reliable indicator for the duration of warm sector precipitation.The vertical upward movement in Shigu was greater than that in Lushan,with the uplift caused by topography constituting only a portion of the total vertical ascent.However,the rate of topographic uplift in Lushan was significantly higher than that in Shigu,indicating a strong influence of topographic uplift.(4)The triggering effect of the heavy rain surface system in Lushan was dominant.Cold wind advection triggered the initial flow along the mountain.A γmesoscale convergence line and the cold pool maintained in the"∧"type valley after rapidly descending the mountain triggered the torrential rain in Lushan at night,and its echo was quasi-stationary backward.By contrast,the Shigu rainstorm was triggered by the 500 hPa trough,weak cold advection,and northward movement of the cold pool in the southwestern Sichuan Basin.The train effect was obvious in this case.The maintenance mechanism of rainstorms in both phases included unstable maintenance and growth caused by the transport of water vapor and energy by easterly air at low levels and strong and continuous rotating upward movement.关键词
暖区暴雨/地形/地形抬升速度/机制Key words
warm-sector rainstorms/topography/topographic uplift rate/mechanism分类
大气科学引用本文复制引用
黄楚惠,李国平,牛金龙,肖递祥,杨康权,陈朝平..四川盆地西部不同形态地形下一次暖区特大暴雨的两阶段比较分析[J].热带气象学报,2025,41(1):41-54,14.基金项目
国家自然科学基金项目(42175002) （42175002）
国家重点研发计划项目(2021YFC3000905) （2021YFC3000905）
四川省科技计划重点研发专项(2022YFS0542) （2022YFS0542）
四川省自然科学基金项目(2023NSFSC0242) （2023NSFSC0242）
中国气象局创新发展专项(CXFZ2021Z33、CXFZ2021J27) （CXFZ2021Z33、CXFZ2021J27）
四川省气象局项目(SCQXKJYJXMS202113、SCQXKJZD202101) （SCQXKJYJXMS202113、SCQXKJZD202101）
川西南(雅安)暴雨实验室科技发展基金项目(CXNBYSYSYWZD202404) （雅安）
四川省气象局智能网格预报创新团队项目共同资助 （）
