Optimization of Parameterization in Ionospheric Tomography

Zhizhao Lin and Yang Gao

Abstract:	The development of a three-dimensional (3D) ionosphere model using tomography methodology is described in this paper. Ionospheric tomography can be modeled horizontally by a series of spherical harmonics functions (SHFs) and vertically by empirical orthogonal functions (EOFs) based on the total electron content (TEC) observations derived from dual-frequency GPS data. In ionospheric tomography modeling, one of the key issues is how to determine the appropriate number of model parameters, namely the truncation limits of the harmonics functions and EOFs. Several influence factors must be taken into account such as the size of the GPS network, GPS data volume, and the time scale of the data acquisition. Either over-parameterization or under- parameterization will lead to a degradation of ionospheric modeling accuracy. An optimal parameterization should result in smallest discrepancy between the model inferred ionospheric delay and the direct ionospheric measurements. Extensive computations have been made to analyze how to maximize the model recovering capability through optimal parameterization.
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:	2277 - 2285
Cite this article:	Lin, Zhizhao, Gao, Yang, "Optimization of Parameterization in Ionospheric Tomography," 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. 2277-2285.
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