一次高原强降雪过程三维对称不稳定数值模拟研究  

Numerical Study of 3－Dimensional Conditional Symmetric Instability of a Heavy Snowstorm

作　　者：王文[1] 刘建军[2] 李栋梁[3] 翟志宏 

机构地区：[1]兰州大学 大气科学系,甘肃兰州730000 [2]宁夏气象局科研所,宁夏银川750002 [3]中国科学院 寒区旱区环境与工程研究所,甘肃兰州730000

出　　处：《高原气象》2002年第2期132-138,共7页Plateau Meteorology

基　　金：国家自然科学基金项目(40145021)资助

摘　　要：利用一次较成功地模拟了“９７．１２”青藏高原东南部暴雪过程的ＭＭ５中尺度模式输出资料，　用非纬向非平行基流中的对称不稳定模式，　对“９７．１２”暴雪发生发展过程的动力学机制进行了三维基流中二维非线性对称不稳定数值模拟试验。结果表明：　％ψ场和ｗ％场的三维配置在降雪发生前和发生初期与暴雪带基本一致，　说明非线性对称不稳定是这次高原暴雪启动的一种动力学机制。A 3－dimensional non－zonally and non－parallel basic flow numerical simulation scheme with nonlinear symmetric instability theory is designed to simulate the mechanism of a heavy snowstorm of 10-12 December 1997 “97.12” occurred in the southeast region of Qinghai－Xizang Plateau by using the output data of a MM5 mesoscale numerical model which fairly well simulated the developing structure and the evolution of “97.12” snowstorm, it suggested that in a developing model of two－dimensional nonlinear SI in a three－dimensional basic flow with proper parameters the CSI be one of the mechanisms of triggering and organizing the banded system on which the snowstorm formed. The circulations of symmetric perturbation fields which slant to south with height in %y-z% cross section by symmetric instability and are vertical in the along－front direction by nonlinear transversal wave instability merged in the model, not only the fields of vertical velocity are coincident with that of streamfunction, but also with the observations. This shows the CSI is substantially a dynamic mechanism before and on the early stage of the occurrence of the “97.12” snowstorm.

关 键 词：高原暴雪 三维对称不稳定 数值模拟 降雪过程分析 1997年 动力学机制 

分 类 号：P458.121[天文地球—大气科学及气象学]