温度扰动激发的重力波波包非线性传播过程的数值研究

A NUMERICAL STUDY ON THE NONLINEAR PROPAGATION OF GRAVITY-WAVE PACKETS EXCITED BY TEMPERATURE DISTERBANCE

采用谱配置方法建立了一个中层大气扰动传播的全非线性动力学数值模型,利用该模型对具有高斯分布的波状温度扰动在可压大气中的演变和传播过程进行数值模拟.模拟结果表明:温度扰动很快就会激发出两支重力波波包,其中一支向上传播,而另一支则向下传播;这两支重力波波包的传播路径与线性理论给出的射线路径有些差异.进一步的数值分析则表明,给定的温度扰动在经过了约3h的演变后,完全转化为波动,在这个转化过程中,79％的扰动能量转化为波动能量.

By using the spectral allocation method, a fully-nonlinear dynamical numerical model for the propagation of disturbance in the mesosphere is found. Applying the newly founded numerical model, the evolution and propagation of an initially given Gassian wave-like temperature disturbance in a compressible atmosphere were simulated. The simulation results show that the temperature disturbance excites two gravity-wave packets soon, one propagates upward and another propagates downward. The energy propagation paths of these two packets are slightly different from the ray paths predicted by the linear theory. A further numerical analysis indicates that after 3 hours' evolution of the initially given temperature disturbance, the disturbance converts entirely to wave motion, and during the conversion, only 79% disturbance energy is converted to be wave-associated energy.