Ionosphere TEC Estimation of the Sky over Japan Based on Spherical Cap Harmonics

Abstract

In [1], the authors have developed a method of estimating the local models of an ionosphere VTEC (Vertical Total Electron Content) [2] based on GNSS (global navigation satellite systems) regression models (abbreviated by GR models) and we have shown the ionospheric delay (or advance) in the sky over Japan using the Gps Earth Observation NETwork (GEONET) data provided from the Geographical Survey Institute (GSI) of Japan [3]. In the GNSS positioning, the ionospheric delays are predominant error factors. Therefore, it is important to correct them for higher accurate positioning. In this paper, we present a method of estimating an ionospheric TEC (Total Electron Content) based on GNSS Regression Models. The method of estimating the local models with power series in Spherical Cap Harmonics Expansion (SCHs) [4] for TEC at the ionospheric pierce points in the ionospheric single layer model is discussed.