The Ohio State University IGS LEO/GPS Pilot Project: Status and Future Plans

Dorota A. Grejner-Brzezinska, Jay H. Kwon and C.K. Shum

Abstract:	The Ohio State University has recently established an IGS LEO/GPS Associate Center for LEO/GPS orbit determination in near real-time, to support atmospheric data retrieval from the occultation events. In addition, 16 permanently tracking GPS stations are currently being established throughout the State of Ohio, and along the Great Lakes shore line. The accurate retrieval of water vapor profiles from GPS occultation data for atmospheric study requires precise knowledge of the 3D position and velocity vectors of both, the GPS and LEO satellites with respect to the center of mass of the Earth. The LEO position and velocity are required with accuracy of 10 cm and 0.1 mm/s RMS, respectively [Rocken et al., 1997; Zhao, 1998]. Even more stringent, from the operational standpoint, might be the need for near-real time retrieval of atmospheric profiles for potential contribution of GPS/LEO data to operational weather forecasting. The primary objective of this paper is to present the currently established procedures and techniques for the Center’s operations that will support occultation data processing, as well as atmospheric data retrieval from the land-based GPS network. In particular, we will focus on the GPS/LEO precise orbit determination (POD) with special emphasis on triple difference-based kinematic approach for LEO POD. The triple difference technique, successfully applied to GPS POD, has already been presented by Grejner-Brzezinska [1995], Yang [1995], Goad et al. [1996] and Kwon [1997]. We have now extended this method to LEO POD. Preliminary results of kinematic LEO POD for CHAMP are also presented. In addition, data screening and quality control procedures applied to CHAMP and ground station GPS data are also presented, with preliminary statistics related to the number and the distribution of cycle slip events. Comparison of the results from two cycle slip detection methods is also included.
Published in:	Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001) September 11 - 14, 2001 Salt Palace Convention Center Salt Lake City, UT
Pages:	2263 - 2271
Cite this article:	Grejner-Brzezinska, Dorota A., Kwon, Jay H., Shum, C.K., "The Ohio State University IGS LEO/GPS Pilot Project: Status and Future Plans," Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001), Salt Lake City, UT, September 2001, pp. 2263-2271.
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