Modeling and Prediction of Regional Ionospheric VTEC for Japanese Region by Spherical Cap Harmonic Analysis

Masaharu Ohashi, Yutaro Sato, Akihiro Yamada, Yukihiro Kubo and Sueo Sugimoto

Abstract:	In this paper, we present the regional ionospheric delay models for Global Navigation Satellite System (GNSS) by spherical cap harmonic analysis (SCHA). The vertical total electron contents (VTECs) are modeled for the ionospheric delays by using the GNSS observation data from GNSS earth observation network (GEONET) of the Geospatial Information Authority of Japan (GSI) in this research. In our previous researches, Japanese regional ionospheric VTECs have been modeled by spherical cap harmonic analysis (SCHA). The SCHA is derived by solving the boundary conditions of spherical harmonic functions. The SturmLiouville boundary conditions (mixed Dirichlet and Neumann boundary conditions) on the colatitude (90 [deg] - latitude) in spherical harmonic functions are solved. On the other hand, in this paper, we show that solving only Neumann boundary condition is better for the regional VTEC model. In order to solve the boundary condition, the Legendre functions of non-integer degree are considered. In the experiments, we evaluate the proposed SCHA and the original SCHA by comparing the regional ionospheric delay models of both analysis methods. We also investigate the prediction of ionospheric delays with the post-processing models developed by the SCHA. We have proposed the prediction methods by periodic autoregressive (PAR) models.
Published in:	Proceedings of the 28th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2015) September 14 - 18, 2015 Tampa Convention Center Tampa, Florida
Pages:	1115 - 1122
Cite this article:	Ohashi, Masaharu, Sato, Yutaro, Yamada, Akihiro, Kubo, Yukihiro, Sugimoto, Sueo, "Modeling and Prediction of Regional Ionospheric VTEC for Japanese Region by Spherical Cap Harmonic Analysis," Proceedings of the 28th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2015), Tampa, Florida, September 2015, pp. 1115-1122.
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