秦岭山脉南北麓暴雨触发条件对比分析  

Comparative Analysis of Rainstorm Triggering Conditions at the Northern and Sorthern Piedmont of the Qinling Mountains

作　　者：武麦凤[1] 乔舒婷 郭大梅[2] 任小同 WU Maifeng;QIAO Shuting;GUO Damei;REN Xiaotong(Weinan Meteorological Bureau of Shaanxi Province,Weinan 714000,Shaanxi,China;Shaanxi Meteorological Observatory,Xi'an 710014,Shaanxi,China)

机构地区：[1]渭南市气象局,陕西渭南714000 [2]陕西省气象台,陕西西安710014

出　　处：《高原气象》2025年第1期178-190,共13页Plateau Meteorology

基　　金：中国气象局创新发展专项项目(CXFZ2023J031);陕西省自然科学基础研究计划项目(2023-JC-YB-283);秦岭和黄土高原生态环境气象重点实验室开放研究基金课题(2021K-4);渭南市气象局科研项目(2023wk-2)。

摘　　要：采用实况气象观测资料、FY-2G卫星云图资料、多普勒雷达资料和ERA50.25°×0.25°逐小时再分析资料,对2021年8月21-22日同时发生在秦岭南北麓的强等级暴雨过程进行对比分析,探讨秦岭南北麓暴雨触发条件的影响机制。结果表明:秦岭北麓流场上,西风带系统在秦岭特殊地形作用下,对流层低层形成中尺度气旋性环流,通过热力作用触发暴雨,对流性降水持续时间短,强度小;湿斜压性增强是秦岭北麓暴雨开始的一个信号,当湿斜压性减弱以及中层比湿减小时,降水结束。对秦岭南麓而言,地形作用下对流层低层流场形成中尺度辐合线触发暴雨;降水释放的凝结潜热加热低层大气,与中低层入侵的冷空气共同构建对流不稳定结构,上升运动增强,降水增强和持续;对流云团在高温高湿的环境下迅速组织化合并发展,形成中尺度对流复合体(MCC),对流强度大,对流层结深厚,小时雨强大;中低层冷空气的入侵和扩散到地面的时间分别与秦岭南麓强降水的开始和结束时间对应。A heavy rainstorm process occurring simultaneously at the northern and southern piedmont of the Qinling Mountains from August 21 to 22,2021 is compared and analyzed to explore the influence mechanism of the triggering conditions at the northern and sorthern piedmont of the Qinling Mountains by using the real-time meteorological observation data,FY-2G satellite cloud images,doppler radar data and ERA50.25°×0.25°hourly reanalysis data.The result shows that on the flow field of the northern piedmont of the Qinling Mountains,the westerly system forms a meso-scale cyclonic circulation in the lower troposphere under the special topography of the Qinling Mountains,which triggers heavy rainfall through thermal effects.Convective precipitation is shortlived and its intensity is weak.The enhancement of wet baroclinicity is a signal of the beginning of the rainstorm at the northern Qinling Mountains.The precipitation ends when the wet baroclinicity weakens and the specific humidity of the middle layer decreases.For the southern piedmont of the Qinling Mountains,the formation of mesoscale convergence lines in the lower tropospheric flow field under the effect of topography triggers the rainstorm.The condensation latent heat released by precipitation heats the lower atmosphere and establishes a convective instable structure,together with the cold intrusion in the middle and lower layers,which leads to the enhancement of the upward movement and the precipitation.Under the high temperature and humidity environment,the convective cloud organizes and develops rapidly to form the MCC,which has a high convective intensity,deep convective tropospheric junctions,and powerful hourly rainfall.The timing of the invasion and diffusion of cold air in the lower and middle layers to the ground represent the beginning and end of heavy rain at the sorthern Piedmont of the Qinling Mountains respectively.

关 键 词：秦岭地形 暴雨 动力作用 热力作用 

分 类 号：P458[天文地球—大气科学及气象学]