2-D Propagation Modeling in Inhomogeneous Refractive Atmosphere Based on Gaussian Beams Part II: Application to Radio Occultation

Abstract : The Gaussian beam for atmospheric refraction (GBAR) method is used to model the effects of the refractive atmosphere between a global navigation satellite system (GNSS) satellite and a low earth orbit (LEO) satellite in a radio occultation (RO) configuration. The wave transmitted by the GNSS satellite is expanded into Gaussian beams using a multibeam expansion procedure (MEP). The wave is modeled in the troposphere by Gaussian beams, and additional MEPs are processed if needed. The refractive atmosphere is modeled by a grid of rectangular cells within each of which is defined a constant and vertical refractivity gradient. The propagation factor at the LEO satellite is used to retrieve the refractivity profile at the perigees. The inverse method is recalled, and the global spherical symmetry assumption is emphasized. The inversion of the simulated propagation factor amplitude data is tested in two simulations. The first one considers a spherically symmetrical refractive atmosphere characterized by a standard exponential refractivity distribution. The second one uses data from weather research and forecast (WRF) simulations in the Caribbean region. The error brought by the spherical symmetry assumption is investigated. The GBAR method provides a new tool for the remote sensing of planetary atmospheres.