geometrical (ray) optics
Ya.A. Ilyushin, V.I. Zakharov
Models of irregular disturbances of refractivity field in the lower atmosphere, which are derived from the earlier theoretical and experimental data, are proposed and tested. Based on parabolic equation in diffraction theory for numerical simulations of the GPS-signals propagation in the inhomogeneous terrestrial atmosphere are performed.
The amplitude and phase signal fluctuations on quasi-tangential rays at various levels small-scale inhomogenues in refraction of the environment are investigated as the results of carried out numerical experiment. It was pointed out, that up to sizes of gradients of refractivity index in irregular structures of 5 N-units/km the geometrical optics approach is fair. Between that, even at meanings of small-scale refractivity gradients, under the order of size conterminous with a gradient in a regular layered atmosphere, the formation of space-time caustics are possible.
Comparative analysis of the simulations results together with the real radio occultation data from the CHAMP experiment is given.
Summarizing, we shall note, that increase of definition of meteoparameters accuracy for various, and first of all predicted, aims and adequate interpretation of the data received by radio occultation method are possible only at the account of small-scale medium structures.
Keywords: radio occultation, small-scale inhomogenues, parabolic equation, geometrical (ray) optics, CHAMP mission.