The Simulation Investigation Of Nonlinear Propagation Of Gravity Waves In Three-dimension Compressible Atmosphere

In this dissertation, the development of the gravity waves' propagation and the basic propagation characteristics of the gravity waves are introduced first. Then three-dimension full-implicit-continuous-Eulerian scheme (FICE) which is used to simulate the nonlinear propagation of gravity waves is given in detail, including the finite difference method of fluid dynamics equations, the specification of boundary condition , the determination of time step length and so on. By using FICE scheme, numerical simulation of nonlinear propagation of gravity wave packet in three-dimension compressible atmosphere is presented. Considering an upgoing Gaussian gravity wave packet as an initial perturbation, we display the whole nonlinear propagation process of the gravity wave packet, investigate the characteristics of the nonlinear propagation of the gravity wave packet in the middle and upper atmonphere. The research contents and numerical results are :1. Assuming the initial background is an isothermal and hydrostatic equilibrium atmosphere in which the horizontal pressure gradients are balanced by the geostrophic winds, we study the nonlinear propagation characteristics of the gravity waves, analyze the influence of the earth's rotation on the propagation of gravity wave and compare the simulation results with that obtained by the linear gravity theory. We find that the nonlinearity is significant but far away from the strong nonlinearity, so the nonlinear propagation characteristics is consistent with the conclusions according to the linear gravity theory, this also indicates FICE scheme...