地形Rossby波相速和稳定性数值计算  

Numerical calculations on the phase velocity and growth rate of topographic Rossby wave

作　　者：黄瑾[1] 董婕[2] 

机构地区：[1]南京工程学院基础部,江苏南京211167 [2]陕西师范大学旅游与环境学院,陕西西安710062

出　　处：《西北大学学报（自然科学版）》2004年第4期379-382,共4页Journal of Northwest University（Natural Science Edition）

基　　金：国家自然科学基金资助项目(40071005;40275021)

摘　　要：目的　利用考虑地形影响的浅水波模式研究地形坡度对地形Rossby波相速和稳定性的影响。方法　对特征值问题形式的β平面通道内波动控制方程离散化后进行数值计算,求出地形Rossby波相速和增长率的数值解。结果　地形坡度越大,扰动波长越长,地形Rossby波相速越慢,当扰动波长和地形坡度大于一定值后,地形Rossby波将呈现准定常特征,甚至出现向西传播。结论　考虑了地形坡度作用以后,地形Rossby波相速将减小,并且有可能出现不稳定增长,最不稳定波长随基本气流强度的增强而增加,当基本气流流速为10m/s(20m/s)时,最不稳定波长约为2400～2500km(3000km)。Aim The effects of topographic gradient on the phase velocity and growth rate of Rossby wave are investigated in terms of a shallow water model with topography.Methods The calculation is conducted by use of solving a eight-value problem about complex phase velocity on β-plane numerically. Results The greater the topographic gradient and the longer the wave length, the slower the phase velocity of the topographic Rossby wave, and the wave will be stationary or propagate westward when the wave length is longer enough with a greater topographic gradient.Conclusion The phase velocity of Rossby wave will be slower and the perturbation will become unstable when the effect of topography is included in the model, and the wave length of the most unstable wave is increasing with the strength of basic west flow, which is about 2 400～2 500 km (3 000 km) for basic flow 10 m/s (20 m/s).

关 键 词：地形Rossby波 地形梯度 相速 稳定性 

分 类 号：P435[天文地球—大气科学及气象学]