摘要
1996年 8月 3～ 5日 (“96· 8”) ,中国河南、山西、河北等省发生了一次特大暴雨过程 ,造成了严重洪涝灾害。文中的天气分析指出 ,稳定的大型鞍形场和北移台风 (登陆后减弱为低压 )与其东侧副热带高压的相互作用是“96· 8”特大暴雨发生的大、中尺度环流条件 ;而中尺度低压及其特有的动力热力结构与该暴雨过程直接相关。对该过程采用非静力中尺度数值模式 (MM5)进行了数值模拟研究。模拟结果分析发现 ,非静力 (MM5)的全物理过程模拟基本上可再现大尺度和中 -α尺度天气系统的发生、发展和演变。采用二重网格双向嵌套技术的细网格模拟结果揭示 ,低压的动力场和热力场之间具有一种强耦合机制 ,即发展的低压具有气旋性涡柱的暖心高湿结构 ,在涡柱低空是湿对流不稳定和负湿位涡结构 ;强垂直上升运动与高空强辐散和低空强辐合以及对流云团的发展互耦 ;与低压相伴的强南风急流不仅是低压和对流云团发展与维持的互伴互耦条件 ,而且也是“96· 8”特大暴雨的水汽源和热能输送带。降水模拟结果分析表明 ,尽管某些降水中心对粗网格偏小 ,对细网格偏大 ,但雨带和雨强分布与观测结果基本一致。
During the period 3-5 August 1996(“96·8”), an extraordinary heavy rainfall event occurred in Henan, Hebei and Shanxi Provinces in China, resulting in severe flood catastrophe. Synoptic analyses indicate that the stable gross col field and the interaction between a northward moving typhoon(down into low pressure) and its east lateral Pacific subtropical high were the large scale and mesoscale circulation conditions of the occurred “96·8” extraodinary heavy rainfall; The mesoscale typhoon low pressure and its specific dynamical and thermodynamical structures were directly related to this heavy rainfall event. Using the nonhydrostatic version of mesoscale numerical model MM5 to conduct investigation of numerical simulation for this case, the simulation of the full physics processes of nonhydrostatic version MM5 was basically possessed of a capability to reproduce the genesis, development and evolution of the large scale and meso α scale weather systems. The simulative results using a two way interactive nesting procedure revealed that the typhoon low pressure possessed an intensive coupled mechanism between the dynamical and thermodynamical fields, namely, the developing typhoon low was possessed of a structure of the column of cyclonic vorticity with warm center and high humidity, within the lower levels of the vorticity column were associated with the moist convective instability and negative moist potential vorticity structure; the intensive ascending motion and the intense convergence (divergence) on the lower (upper) levels as well as the development of the convective cloud cluster were intercoupling; the intense south wind jet stream below 500 hPa accompanied by the typhoon low was not only the interaccompany and intercoupling condition of the development and maintenance of the typhoon low and convective cloud cluster,but also was the moisture source and heat energy transport belt of the “96·8” extraordinary heavy rainfall. The simulative results of precipitation show that the rain band and rainfall distribution of precipitation with that of the observation were basically consistent in spite of some rainfall centers less or larger than those of observations for coarse or fine mesh, respectively.
出处
《气象学报》
CSCD
北大核心
2001年第3期294-307,共14页
Acta Meteorologica Sinica
基金
国家重点基础研究项目 ( G1 9980 4 0 90 7)
国家自科学基金项目
关键词
特大暴雨
台风
天气过程分析
数值模拟
中尺度结构
非静力MM5
对流云团
Extraordinary heavy rainfall, Nonhydrostatic MM5, Two way interactive nesting, Numerical simulation, Mesoscale structure.
