一次“北涡南槽”型广西强降水过程的数值模拟与诊断分析  

NUMERICAL SIMULATION AND DIAGNOSTIC ANALYSIS OF A HEAVY PRECIPI-TATION EVENT OCCURRED IN GUANGXI ZHUANG AUTONOMOUS REGION UNDER SITUATION OF SOUTH TROUGH AND NORTH VORTEX

作　　者：覃丽[1] 寿绍文[1] 刘泽军[2] 陆汉城[3] 

机构地区：[1]南京信息工程大学大气科学系 [2]广西气象减灾研究所,广西南宁530022 [3]解放军理工大学气象学院,江苏南京211101

出　　处：《热带气象学报》2007年第1期27-34,共8页Journal of Tropical Meteorology

基　　金：国家自然科学基金项目(40405009;4057022;40205008);国家重点基础研究发展规划项目(2004CB418301);江苏省自然科学基金项目(BK2005141);江苏省气象局科技开发项目(200406);江苏省气象灾害重点实验室项目(KLME050201)

摘　　要：利用MM5V3.6模式对2005年4月25日一次典型的西南涡影响下的广西强降水过程进行了数值模拟与诊断分析,结果表明,在500hPa低槽、700hPa西南涡东南移的过程中,在西南涡的南端,由于对流层高层高值干位涡下传引起低层气旋性涡度增加,低涡向南伸出一低槽,使西南涡发展成“北涡南槽”形式,广西强降水出现在西南涡的南伸低槽附近。西南涡的南伸低槽附近垂直剖面上为等θe线陡立密集区,700hPa上MPV1<0,MPV2>0,低层有强烈辐合,高层有强烈辐散,从低层到高层都有上升运动。螺旋度对强降水的落区以及造成强降水的中尺度系统的发展有较好的指示性,它反映了大气的动力场特征,运用螺旋度作强降水预报还要结合水汽和不稳定条件。The numerical simulation and diagnostic analysis of a heavy precipitation event that occurred in Guangxi on April 25, 2005 is conducted by using the NCAR/PENS mesoscale numerical model MM5V3.6. It is shown that the downward -spreading high-value dry potential vorticity leads to the development of a trough to the south of the cyclonic vortex. The heaW precipitation occurred in the vicinity of the trough. In the trough there are very stiff, moist insentropes in the vertical section, MPV 1〈0 and MPV 2〉0 at 700hPa, low-level atmosphere convergence, upper-level divergence and strong vertical velocity. Helicity is a good indicator for the location of heavy precipitation and the development of the mesoscale weather system causing the heavy precipitation. Helicity as a dynamical factor must be combined with moisture and instability conditions when it is used to forecast heavy precipitation.

关 键 词：西南涡 强降水 数值模拟 诊断分析 

分 类 号：P456.7[天文地球—大气科学及气象学]