一次梅雨锋降水雨带演变动力学特征分析  

Dynamic Feature Analysis of the Evolution of Rain-band Along Meiyu Front

作　　者：王勇[1,2] 丁治英[1] 陈明诚[1] 

机构地区：[1]南京信息工程大学气象灾害省部共建教育部重点实验室,江苏南京210044 [2]南京信息工程大学世界气象组织南京区域培训中心,江苏南京210044

出　　处：《地理科学》2013年第9期1132-1137,共6页Scientia Geographica Sinica

基　　金：国家重点基础研究发展项目规划"973"(2013CB430103);国家自然科学基金项目(40975037)资助

摘　　要：采用非静力中尺度数值模式WRFv3.1数值模拟结果、FNL再分析资料以及实况降水资料对一次梅雨锋暴雨其雨带演变特征进行天气动力学分析。借鉴经验正交函数EOF分解技术,揭示对此次降水过程雨带分布具有重要影响的低层风场演变过程,在此基础上结合垂直涡度倾向变化方程,对雨带上中尺度涡旋演变机制进行初步分析。结果表明:①雨带的演变与低空急流的形成、发展有关,雨带在此次降水阶段后期沿着新生成的低空急流不断向东移动、发展。②对流层中低层涡度平流项、垂直输送项演变过程对于雨团移动具有指示作用。③低空风垂直切变加强以后,涡度方程中扭转项对局地涡度发展具有重要作用。The simulation results of nonhydrostatic mesoscale numerical model WRFv3.1, FNL reanalysis data and observation precipitation data are used to perform the synoptic dynamic analysis of the rainstorm over Mei- yu front and the evolution characteristics of rain band in Huaihe River Basin. In this article, we draw on the de- composition technique of empirical orthogonal function （EOF） to reveal the evolution of low level wind field, which has an important influence on the distribution of mesoscale rain band during this precipitation process. The first mode of EOF analysis performed for horizontal wind at 850 hPa reflects that the southwester strength in the later rainstorm process caused the change of rain band distribution. Based on that and by combining with vertical vorticity tendency equation, a preliminary analysis of mesoscale vortex＇ s evolution mechanism in rain band has been conducted. Results show that： 1） The evolution of rain band is relative to the initiation and devel- opment of low level jet, moving and developing east along the newly generated low level jet in the later stage of the precipitation. 2） The evolution of vorticity＇s horizontal ＆ vertical advection terms indicate the move- ment of rain group and it develops in the moving direction at middle and low levels. The positive vorticity cen- ter is prone to move and develop from the negative vorticity＇ s horizontal advection area to the positive one. The vertical advection transports term upward the vorticity center caused by the convergence movement at low level. Therefore, the vorticity and its horizontal advection at middle level strengthen, promoting the vortex moving and developing downstream.3） The vertical motion benefits the evolution from horizontal vortex tube to vertical vorticity after wind vertical shear at low level strengthens. Thus, the twisting term in vorticity equa- tion plays an important role in the development of local vorticity.

关 键 词：天气学 雨带 EOF 低空急流 涡度平流 

分 类 号：P426.6[天文地球—大气科学及气象学]