Ionospheric Estimation over Japan Based on GNSS Regression Models and GEONET Data

摘要

In this paper, we present an ionospheric estimation method based on GNSS Regression models (abbreviated by GR models) and show to derive the ionospheric delay (or advance) local model in the sky over Japan using the Gps Earth Observation NETwork (GEONET) data provided from the Geographical Survey Institute (GSI) of Japan. First we introduce the very powerful models of observables in GPS/GNSS; called GR models. By applying GR models, we have already developed the precise point positioning (PPP) algorithm and the very precise point positioning (VPPP) algorithm with multiple antennas. These positioning algorithms achieved the positioning accuracy in decimeter level. These algorithms do not require the realtime transmitted information such as from WAAS etc. By showing the GR models for GNSS observables in the case of known positions (in the reference stations), we derive a method to estimate the ionospheric delays (or advances) as well as the so-called integer ambiguities contained in L1 and L2 band carrier-phase data at the reference stations. Then we emphasize the importance to estimate integer ambiguities of their own receivers at the reference stations. Further, we derive the method of estimating the local model with power series for the vertical total electron content (VTEC) at the ionospheric pierce points in the ionospheric single-layer model by using GPS receiver’s data at many reference stations. Finally the local estimated model of the vertical TEC in the sky over Japan using GEONET data is shown comparatively with applying Klobuchar’s model and with the Global Ionosphere Maps (GIMs) provided by the International GNSS Service (IGS).