一次高原强降雪过程三维对称不稳定数值模拟研究

利用一次较成功地模拟了"95.1"青藏高原暴雪过程的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"95.1"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初期和发展过程中与暴雪带基本一致,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。

Numerical Study of 3-Dimensional Conditional Symmetric Instability for "95.1" Heavy Snowstorm

A 3-dimensional numerical simulation scheme with nonlinear symmetric instability theory is designed to simulate the mechanism of a heavy snowstorm occurred on 17-18 January 1995("95.1") in the southeast region of the 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 the "95.1" snowstorm.It suggested that 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 emerged in the model,not only the fields of vertical velocity are coincident with that of streamfunction,but also with the observations.The CSI is substantially a formative mechanism before and on the early stage of the occurrence of the "95.1" snowstorm.