2019, 39(4): 449-459.
doi: 10.11728/cjss2019.04.449
Abstract:
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 λx ranges from 2.5 to 5km, and the vertical wavelength λz 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.