High-precision VTEC derivation with GEONET

Qi Li,Guanyi Ma,Jie Zhang,Jinghua Li,Jiangtao Fan,Qingtao Wan,Xiaolan Wang,Takashi Maruyama

doi:10.1186/s40623-020-1137-0

Abstract

This paper proposes a new technique, namely Phase bias-based Small Grid Model (PSGM), to derive absolute ionospheric vertical total electron content (VTEC) with observations of Global Navigation Satellite System Earth Observation Network of Japan (GEONET). The proposed technique deals with the phase observations alone without handling the pseudoranges, which reduces the noise in VTEC estimation. A new parameter, the arc bias (Barc), is introduced to combine the phase ambiguities and differential phase biases. To solve Barc, equations are constructed under the assumption that the VTEC is identical in the same 0.1° × 0.1° grid. The performance of PSGM is evaluated with the observations in solar maximum year 2014. The root mean square error (RMSE) of PSGM is 0.40 TECU in average, the maximum RMSE is 0.73 TECU and the minimum RMSE is 0.26 TECU. The fitting accuracy of the VTEC results is improved compared with most of the existing methods.

Highlights

In the past 30 years, dual-frequency Global Positioning System (GPS) has become the most important approach for absolute vertical total electron content (VTEC) measurement
The accuracy of Phase bias-based Small Grid Model (PSGM) are validated with the observation in solar maximum year 2014, and the estimated VTEC result is compared with the International Reference Ionosphere 2016 (IRI) model (Bilitza et al 2017) and the VTEC products of University of Bern (UNIBE) (Schaer et al 1996)
Due to the narrow station distribution of GEONET, when the shell height parameter is too large, the number of neighbor ionospheric piercing point (IPP) pairs composed of different satellites will be greatly reduced, and the PSGM-root mean square error (RMSE) will always tend to decrease as shell height parameter increases

Summary

Introduction

In the past 30 years, dual-frequency Global Positioning System (GPS) has become the most important approach for absolute vertical total electron content (VTEC) measurement. In order to obtain more accurate absolute VTEC, a phase bias-based Small Grid Model (PSGM) is proposed for VTEC derivation with GEONET, which is the world’s densest GNSS observation network.

Results

Conclusion