重力波波包在可压大气中的非线性传播

本文采用二维全隐欧拉（ＦＩＣＥ）格式对具有高斯发布的重力波波包在等温、可压大气中的非线性传播过程进行数值模拟和分析。数值分析结果表明：尽管存在非线性效应，在整个传播过程中，波动的等相面向下运动，波包和波相关能量向上传输。波相关扰动速度随高度增加指数增长，并且波与平流会发生非线性相互作用，最后导致平均流场增强。这与线性重力波理论完全一致。重力波波包的传播路径与重力波线性射线理论预言非常接近，但平均水

THE NONLINEAR PROPAGATION OF GRAVITY WAVE PACKETS IN COMPRESSIBLE ATMOSPHERE

In this paper, numerical simulation of nonlinear propagation of gravity wave packets with Gaussian distribution in isothermal and compressible atmosphere is presented by using 2-dimentional FICE scheme. The numerical analysis show that though there exists nonlinear reaction, during the propagation process, the phases of waves move downward, the wave packets and the wave-associated energy propagate upward. Wave-associated disturb velocities increase exponentially with the height and the reaction between the waves and the background leads to the enhancement of the mean flow. These agree well with the linear gravity wave theory. The propagation trace of gravity wave packets is consistent with the prediction of linear ray theory, but the average horizontal group velocity and vertical group velocity are obviously smaller than the results given from the linear ray theory. It indicates that the nonlinear process of gravity waves can change the propagation velocities of wave- associated energy. The simulation results show quantitatively that the effect of nonlinearity on propagation of gravity wave packets for the first time, it indicates that the definitions of dynamics of gravity waves given by the linear theory are reasonable.