长江中游一次β中尺度低涡的数值模拟  

ANALYSIS AND NUMERICAL SIMULATION OF A MESO - β - SCALE VORTEX IN THE MIDDLE REACHES OF THE YANGTZE RIVER

作　　者：王智[1] 翟国庆[1] 高坤[1] 

机构地区：[1]浙江大学理学院地球科学系,杭州310028

出　　处：《气象学报》2003年第1期66-77,共12页Acta Meteorologica Sinica

基　　金：973国家重点基础研究发展规划项目(G1998040907);国家自然科学基金资助项目(40075009);浙江省自然科学基金(N29984);杭州市科技发展计划项目(2002214B03)。

摘　　要：利用PSU/NCAR的中尺度数值模式MM5,对1999年6月29日的一次东移低涡过程进行了数值模拟,结果表明:在东移的a中尺度低涡的东南部边界层激发出一个β中尺度的涡旋,该β中尺度涡旋与一强暴雨区相伴移动,稠密的实况降水资料证实了这一暴雨雨团的存在和移动过程。模拟分析揭示β中尺度涡旋出现在停滞的α中尺度低涡南侧偏西气流与暖区偏南气流相遇处及中尺度山脉的背风坡;在中尺度山脉背风坡的地面和近地面层分别有中尺度低压和增强的东南气流存在,由此产生或加强了近地面的强涡度和强辐合,有利于对流系统的发生发展。A heavy rainfall process took place in the middle and lower reaches of the Yangtze River during 26 - 30 June 1999.The analysis shows that several mesoscale cyclone disturbances along Meiyu front are heavily responsible for this intense precipitation process. An east - moving low vortex in 29 June 1999 was simulated by use of PSU/NCAR MM5 in this paper. The results show that the slow - moving and stagnation of this east - moving meso -α- scale low vortex in the middle reaches of the Yangtze River provided background condition for the formation of a meso -β- scale vortex. And the meso - β- scale vortex was produced in the southeast boundary layer of the east - moving meso - α -scale low vortex. After its formation, this meso - β - scale vortex moved northeast ward accompanied with strong heavy rainfall. The evolution and propagating of this strong heavy rainfall were verified by the dense observational rainfall data. The simulation also shows that the meso - β- scale vortex appeared in the lee side of mesoscale mountain where the westerly flow in the south of the meso - a - scale vortex converged with the southerly flow from warm section. A mesoscale low and strengthened southeasterly flows near surface in the lee side of the mesoscale mountain strengthened the vorticity and convergence near surf ace, which was helpful to the development of the meso - β - scale convective system. When the meso - β - scale vortex moved east to Boyang Lake, the easterly flow in the north of vortex was hampered by the Dabie mountain and turned to south, and strengthened the cyclone circulation in the back of the meso- β- scale vortex. Then under the influence of the southerly flow in the boundary layer, severe convergence and upward movement appeared in the meso ?(3 ?scale vortex. The cyclone circulation developed to high levels, and the meso - β - scale vortex developed to be a meso - a - scale vortex system at last.

关 键 词：Β中尺度低涡 数值模拟 数值模拟 强对流天气 梅雨锋暴雨 

分 类 号：P435.2[天文地球—大气科学及气象学]