The sensitivity of atmospheric temperature retrieved from radio occultation technique to orbit errors of GPS and LEO satellites

Abstract

In this paper, a broad qualitative description of GPS-based radio occultation technique for the Earth atmosphere limb sounding is given and some equations in the recovery of temperature are summarized. Based on a simple software developed in this work, some quantitative results on this topic are provided. The sensitivity of this technique to orbit errors of GPS and LEO satellites is investigated particularly. Some conclusions are derived as follows. Although a constant extra path delay error due to inaccurate POD information has no effect on the retrieved temperature in radio occultation technique, orbit errors of GPS and LEO satellites, especially for LEO, can result in temperature errors that are not negligible. Temperature errors grow very rapidly with the increasing of the impact height of the ray. The lower LEO orbit altitude, the larger temperature errors are, at the same height and given the same orbit accuracy. There exists an approximately linear relationship between temperature errors and the orbit errors of LEO satellite at each specific height. For upcoming CHAMP satellite, temperature errors are expected to be less than 1 K below 50 km of the minimum ray height if 10 cm orbit accuracy can be obtained in the post-processed case. With 30 cm orbit accuracy, which is the expected obtainable case on near real time situation, temperature errors can be less than 1 K below 40 km height. (orig.)Available from TIB Hannover: RR 6134(98/23) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman