Simulation of the mountain-based radio occultation

In this paper, the mountain-based radio occultation is simulated using the 3D ray tracing technique. The starting time, the azimuth angle and the duration of the occultation events are obtained. The height and the excess phase variations of the occultation caused by water vapor and the temperature variety in the atmosphere boundary layer are studied in details. The influence of the geography on the height of the occultation is analyzed using data observed by CHAMP occultation, and it is very obvious. These results may be significant for explaining occulted processing, signal block and the height variation when the occulted signals' tangent height enters the atmospheric boundary layer.