一次梅雨锋暴雨发生发展机制的诊断与模拟
投稿时间: 2016-02-02  最后修改时间: 2016-04-02  点此下载全文
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闵锦忠 南京信息工程大学气象灾害预报预警与评估协同创新中心 352321105@qq.com 
张申䶮 南京信息工程大学气象灾害预报预警与评估协同创新中心  
杨婷 南京信息工程大学气象灾害预报预警与评估协同创新中心  
基金项目:国家重点基础研究发展计划(973计划);国家自然科学基金项目(面上项目,重点项目,重大项目)
中文摘要:采用NCEP/NCAR再分析资料、FY2E卫星资料和加密自动站资料,结合中尺度WRF模式对2013年苏皖地区的一次梅雨锋暴雨过程进行诊断与模拟。观测资料分析表明:在有利的环流背景和热动力条件下,此次暴雨发生在梅雨锋前暖区,雨带呈现“先带状后串波状”的分布特征,并随锋面南移。前期降水由地面中尺度辐合线触发,由两个相继发展的中α尺度的线状对流系统直接影响;后期降水受地面暖式切变线触发,有多个中β尺度对流系统沿切变线串状排列,并不断东移发展。模拟结果分析表明:降水过程中,大尺度非地转强迫作用也是强对流的触发机制之一。地面辐合线产生条带状的低层辐合区,从而产生条带状连续分布的上升运动,形成线状对流系统及带状降水。此外地面辐合线能够在暴雨区形成南北两个中尺度垂直次级环流圈,是降水的增强机制。暖式切变线上的局部扰动在低层局部地区产生强辐合,由此沿切变线形成强上升弱下沉间隔分布的现象,局部强上升区使得对流系统于该处得到发展,并形成分散的强降水区。
中文关键词:梅雨锋暴雨  中尺度对流系统  辐合线  暖式切变线  数值模拟
 
Diagnosing analysis and numerical simulation of the formation and development mechanism of a rainstorm on Meiyu front
Abstract:Using the NCEP/NCAR reanalysis data, FY2E satellite data and the automatic weather station data combined with the WRF (Weather Research and Forecasting) model, a Meiyu rainstorm occurred on Jiangsu and Anhui provinces was analyzed. The observational data analysis results show that: Under favorable circulation background and thermodynamic conditions, the heavy rain occured in the south warm side of Meiyu front. The rain belt transformed from the ribbon to string shape distribution and move southward along with Meiyu front. Early precipitation was triggered by surface mesoscale convergence line, directly affected by two successive meso-α-scale linear convective systems. Later rainfall was triggered by the ground warm shear line. There are a string of meso-β-scale convective systems development eastward along the shear line. High-resolution model outputs analysis results reveal that large scale non-geostrophic forcing also played an important role in triggering strong convection during this rainstorm. The ground convergence line produced a banded lower layer convergence zone, resulting in strip continuous distribution of ascending motion and then give rise to linear convection system and banded precipitation formation. Additionally, the ground convergence line also formed north and south mesoscale vertical secondary circulation circle, which was enhancement mechanism of precipitation. The local disturbance of warm shear line produced local strong convergence, thus making strong ascending and weak descending interval distribute along the shear line. And then convective systems developed in strong ascending region, bringing local heavy precipitation.
keywords:Meiyu front rainstorm  mesoscale convective system  convergence line  warm shear line  numerical simulation
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