地形产生的山地波及其传播过程模拟研究

气流经过地形产生的山地波是大气重力波研究的重要类别之一.从大气运动的控制方程组出发，建立模拟地形产生的山地波及其传播过程的二维数值模式.利用水平背景风场、地形和垂直速度之间的关系，在模式中引入垂直速度扰动作为地形产生山地波的激发源.通过模拟该激发源引起的扰动即山地波在大气中的传播过程，再现了山地波的产生、传播及充分发展过程.通过分析水平波长、垂直波长、位温扰动、流线，在空间尺度上描述了山地波的产生、传播及充分发展的过程.在气流经过地形产生的山地波的传播过程中，其水平波长λ_x的范围为2.5~5km，垂直波长λ_z约为2.5km.这些结果与利用山地波线性理论计算的垂直波长一致，从而验证了本模式能够模拟地形产生的山地波及其传播过程，为深入了解山地波的产生过程及其在中高层大气中的传播机制和效应奠定了基础. 

Simulation on the Mountain Wave and Its Propagation Generated by Terrain

Mountain waves generated as airflow pass the terrains are one of the important classes of atmospheric gravity waves. Based on the equations of controlling atmospheric motion, a two-dimensional nonlinear numerical model is established to simulate the mountain waves generation and its propagation process. Using the relationship among the horizontal background wind, the terrain and the vertical velocity, a vertical velocity disturbance is introduced into the model to act as the source of the mountain waves. The entire processes of generation, propagation, and fully development of mountain waves are reproduced by use of our model. The aspects of the horizontal wavelength, the vertical wavelength, the potential temperature disturbance and the streamlines are analyzed to describe the characteristics of the mountain wave different stages. During the propagation of the mountain waves, the horizontal wavelength λ_x ranges from 2.5 to 5km, and the vertical wavelength λ_z is about 2.5km. The results are consistent with the calculations by linear theory. The analyses illustrate that the model can successfully simulate the mountain wave generated by the terrains. The study is helpful for understanding the generation and the propagation of mountain waves, as well as their effects on the middle and upper atmosphere.