2005年7月一次大暴雨过程的模拟和诊断分析
投稿时间: 2010-07-12    点此下载全文
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作者单位
张恒德1,宗志平1,张友姝2  
基金项目:1.中国气象局 国家气象中心,北京 100081;2.空军气象中心,北京 100843
中文摘要:基于2005年7月9—10日河南、安徽等地一次大暴雨的巨大影响,利用中尺度模式(MM5)对此次过程进行了模拟,并使用NCEP/NCAR再分析资料和模式输出产品作了多种物理量诊断分析,结果表明,贝加尔湖附近阻高、下游的东北冷涡及其伴随的高空槽造成了有利的环流形势,低层切变线及急流是此次暴雨过程的最主要影响系统。散度、涡度、垂直速度、螺旋度及位温的分布和演变反映出在此次降水发生过程中,暴雨区出现了很强的辐合上升运动,中低层大气层结不稳定性强,上下层大气物质交换强烈,在暴雨区上空螺旋度呈“下正上负”的垂直结构,螺旋度正的大值区对应强降水中心;水汽通量散度的分布说明暴雨区有充足的水汽供应,而锋生条件为降水的形成和维持提供了一定的能量。
中文关键词:暴雨  数值模拟  螺旋度  锋生函数
 
Simulation and diagnosis of a heavy rainfall event in July 2005
Abstract:Due to the enormous disaster caused by the heavy rainfall in Henan and Anhui on 9 July 2005,the process is simulated by using mesoscale model(MM5) and is studied based on NCEP/NCAR re analysis data and product of MM5.The results show that the Baikal blocking,cold vortex over Northeastern China and the high level trough were propitious to the heavy rainfall.The low level jet and shear were the main systems leading to the rainfall.According to the change of divergence,vorticity,vertical velocity,helicity and equivalent potential temperature,it is obviously found that atmosphere converged and ascended,and low mid level stratification instability was very apparent in heavy rainfall area.Additionally,up low level matter exchange was intense.The vertical profile of helicity over heavy rainstorm area was positive in the low middle level and negative in upper level of troposphere.The large positive helicity area corresponded to the center of the rainstorm.Distribution of moist flux divergence presented that there was strong moisture convergence in the rainstorm area.Moreover,frontogenetic condition provided energy and vapor for the rainfall and its reinforcement.
keywords:heavy rainfall  numerical simulation  helicity  frontogenetic function
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