A theoretical model of gravity wave propagation based on the transfer function

In order to study the relationship between the excitation source of gravity wave in the troposphere and the response of ionosphere, a theoretic model of gravity wave propagation based on the complex dispersion relation of internal gravity wave and the conception of transfer function has been built in a dissipative atmosphere which includes viscosity and heat conductivity. In the paper the amplitude of transfer function is discussed in the frequency domain. Through analyzing a case of unit impulse, we obtain the distribution of a certain physical quantity in time and space from earth's surface to 300 kin above. The results reveal that the atmosphere behaves like a filter which offers the easy passage to some gravity waves whose periods range from 15 min to 30 min and the horizontal wave lengths are between 200 km and 450 kin. The response of ionosphere occurs at a large horizontal distance from the source. The viscosity and the conductivity coefficients of atmosphere have small influence in the low atmosphere, but it becomes greater with increasing of height. The frequency obtained by the transfer function model is consistent with that from Row's theory in the low atmosphere, but they differ much in the high atmosphere.