摘要
利用多途径探测与再分析资料,通过诊断分析、数值模拟和敏感性试验,对2008年7月20～21日一次高原涡东移诱生西南涡并引发川中特大暴雨的天气过程进行了初步分析,探讨了西南涡特大暴雨发生的中尺度环境场特征,特殊地形和非绝热物理过程在高原涡东移诱生西南涡特大暴雨中的作用。结果表明,高原涡形成后沿高原东北侧下滑,在四川盆地诱生出西南涡,川中特大暴雨在西南涡形成过程中由强中尺度对流系统(MCSs)的活动造成。高原涡东移诱生的低层偏东气流在川西高原东侧地形的动力强迫抬升作用下,释放对流有效位能激发出MCSs产生强降水,降水凝结潜热加热反馈驱动西南涡快速发展。地形的动力作用仅能形成浅薄的西南涡,降水凝结潜热的加入才能使西南涡充分发展。高原涡的发展主要受地面热通量影响,它的发展与否在很大程度上决定西南涡能否形成。盆地周边高大山脉对西南涡的位置分别有不同程度的影响,而盆地周边高大山脉上叠加的中小尺度地形对西南涡和暴雨带的整体位置影响不大,在一定程度上影响暴雨的落区。
Using the multiple detections,observations-and reanalysis data,it is analyzed a weather process where a Plateau Vortex moved eastward,induced a southwest vortex and produced extremely heavy rainstorm on 20～21 July 2008 by diagnostic analysis,numerical simulation and sensitivity experiment.Then it is investigated the mesoscale environmental-features during the extremely heavy rainstorm,the role of particular topography and diabatic processes in the development,eastward movement,south-west vortex inducing and extremely heavy rainstorm producing of the Plateau Vortex.The results show that the Plateau Vortex moved downward along the northeast side of Tibetan Plateau and induced a south-west vortex in Sichuan basin after its formation.The extremely heavy rainstorm in the middle of Sichuan Province is resulted from severe mesoscale convective systems （MCSs） triggered in the formation of southwest vortex.The easterly winds induced by Plateau Vortex are forced to release convective available potential energy,trigger MCSs and produce intensive heavy rainstorm under the dynamic lifting of the topography in the east of Chuanxi Plateau.The condensation latent heating of precipitation drives the fast development of the southwest vortex.Only formed is a shallow southwest vortex under the dynamic role of the topography.The southwest vortex is sufficiently developed only when the rainfall condensation latent heating is feedback.The development of the Plateau Vortex,which determines the south-west vortex growth to a large degree,is mainly influenced by the surface heat flux.The high mountains around Sichuan basin exert a different influence on the position of southwest vortex respectively,while the microand mesoscale peaks embedded on the high mountains do not greatly affect the position of southwest vortex and heavy rain band,but the rainstorm dropping zone to a certain degree.
出处
《高原气象》
CSCD
北大核心
2010年第4期819-831,共13页
Plateau Meteorology
基金
国家自然科学基金面上项目(40975025)
国家自然科学基金重点项目(40930951)
科技部公益性行业科研专项(GYHY200906010)共同资助
关键词
西南涡
地形
对流
暴雨
高原涡
Southwest vortex
Topography
Convection
Heavy rainstorm
Plateau vortex
