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[18.25] Advances in Multiple Phase Screen Simulation of Thick Atmosphere Radio Occultation

C. S. Han, G. L. Tyler (Stanford University)

Forward simulation of planetary radio occultation plays an important role in the ongoing advancement of methods for constructing accurate atmospheric profiles (e.g., refractivity) from radio occultation data. In such simulations, atmospheric parameters and structure are specified and, hence, are known completely. Therefore, the forward simulation workbench provides a means for understanding how specific atmospheric structures affect real radio occultation experiments and the degree to which such structures may be accurately reconstructed from occultation data.

A typical method for simulating radio occultation utilizes multiple phase screens (MPS). In the MPS method, wave optics effects such as limb diffraction and diffraction from sub-Fresnel-scale atmospheric structure have been successfully represented in simulations for thin atmosphere occultation. Unfortunately, the traditional MPS simulator proves less effective in modeling thick atmosphere occultations. Thick atmospheres refract more strongly than thin atmospheres and are generally more complex (e.g., ducts, critical refraction). As a result of strong atmospheric refraction, the assumption of straight-line paths in a given layer is no longer reasonable. This research describes the limits of the standard MPS approach in modeling thick atmosphere occultation and presents early results toward overcoming such limits by accounting for curved ray paths.

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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.