“7·21”北京大暴雨过程的地形作用分析和数值试验研究  

Diagnostic Analysis and Numerical Simulation of the Impact of Terrain on a Torrential Rain Event in Beingjing on July 21,2012

作　　者：岳甫璐[1] 王春明[1] 崔强[1] 毛天韵 鹿翔 

机构地区：[1]解放军理工大学气象海洋学院,江苏南京211101

出　　处：《沙漠与绿洲气象》2014年第2期41-53,共13页Desert and Oasis Meteorology

基　　金：国家自然科学基金项目(41275113)资助

摘　　要：利用NCEP 1°×1°的6 h再分析资料和常规气象观测资料,对2012年7月21—22日北京地区的大暴雨过程中的地形作用进行诊断分析,研究其对暴雨过程前后的热力、动力及水汽条件的影响。并利用WRFV3.2模式尝试进行一些地形敏感性数值试验,探讨地形改变后对此次暴雨过程的影响,初步得出了一些结论:高空槽配合中层切变线,在低层形成低涡,低涡的东移并加强引发了此次暴雨。暴雨发生前,中低层强的正涡度中心和负散度中心配合很好,它们在东移过程中,组织起了一个很好的垂直环流圈。此环流圈加强了迎风坡气流的上升运动;对流层中低层东南和西南两条水汽通道提供了强大的偏南气流,不断往北京地区上空输送暖湿空气,从而在低层积累了大量的不稳定能量;对流层中低层的位涡从高处往下传,且正位涡中心在东移过程中加强,对应山前迎风坡出现了局地大暴雨,由此说明位涡中心与暴雨落区具有良好的对应关系。地形敏感性数值试验验证了地形虽然对于整体降雨带的影响不大,但对于局地暴雨落区和中心强度的影响却很大。Using 6 hours NCEP 1°×1°reanalysis data and routine observational meteorological data, diagnostic analysis has been performed to research the interaction of orography in the process of rainstorm in Beijing on July 21st, 2012 to discuss the influences of the orography on dynamic process, thermal and moisture conditions in the heavy rain, and to try to perform some numerical experiment about the terrain sensitivity, to discuss the influences of terrain change in height on the weather process. The conclusions has been drawn as follows. The upper trough coupled with warm and wet shear line in the middle level with a vortex developed in the low level. It moved eastward becoming strong so as to cause the rainstorm. Before the heavy rains, the strong positive vorticity coupled with the negative divergence center in the middle and low levels and when moving eastward a good vertical circulation which strengthen upward motion in the windward slope formed;the strong southeast flow was provided by southeast and southwest channels of water in the middle and low level in the troposphere, which constantly transported warm and wet air to the upper atmosphere in Beijing and then accumulated a lot of unstable energy in the low level; a potential vorticity uploaded from the top, and the positive center of potential vorticity became stronger when moving eastward, it correspondingly produced a heavy rainstorm in the windward slope, which showed the result that the center of potential vorticity had a well corresponding relation with the heavy rainfall areas. Some results of the numerical experiment about the terrain sensitivity showed that the influence of orography on the whole scope of rain was small, but it was very significant on the areas and intensity of the local rainstorm.

关 键 词：暴雨 地形 垂直环流圈 位涡 暴雨落区 

分 类 号：P458.121.1[天文地球—大气科学及气象学]