有限振幅重力波波包在等温可压大气中的非线性传播

Nonlinear Propagation of Finite-Amplitude Gravity Wave Packet in an Isothermal Compressible Atmosphere

采用交替方向隐格式(ADI)建立了二维可压大气全非线性动力学模型，模拟了不同初始振幅的重力波波包的非线性传播．模拟结果表明非线性效应是与波振幅相关的；强非线性效应将严重阻碍波振幅的增长，使波数谱明显变化，同时减小了波包的能量传输速度．在传播过程中，强非线性效应将显著加速平均流，其结果与非线性饱和理论的预测接近．

By using the Alternative-Direction-Implicit(ADI)scheme,a fully nonlinear,compres-sible and two-dimensional model is developed to numerically study the nonlinear propagations ofgravity-wave-packets with different initial amplitude.The simulations show that the nonlinear effectsdepend strongly on the wave amplitude.The nonlinearity will damp the wave amplitude growthsignificantly,change the vertical wave numbers,and alter obviously the vertical velocity of energytransmission.The mean flows are accelerated extensively and greatly in the nonlinear propagationof a gravity wave packet with large amplitude.