Algorithm Research Using GNSS-TEC Data to Calibrate TEC Calculated by the IRI-2016 Model over China

Wen Zhang,Zishen Li,Ningbo Wang,Yunbin Yuan,Xingliang Huo

doi:10.3390/rs13194002

Abstract

The International Reference Ionosphere (IRI) is an empirical model widely used to describe ionospheric characteristics. In the previous research, high-precision total ionospheric electron content (TEC) data derived from global navigation satellite system (GNSS) data were used to adjust the ionospheric global index IG12 used as a driving parameter in the standard IRI model; thus, the errors between IRI-TEC and GNSS-TEC were minimized, and IRI-TEC was calibrated by modifying IRI with the updated IG12 index (IG-up). This paper investigates various interpolation strategies for IG-up values calculated from GNSS reference stations and the calibrated TEC accuracy achieved using the modified IRI-2016 model with the interpolated IG-up values as driving parameters. Experimental results from 2015 and 2019 show that interpolating IG-up with a 2.5° × 5° spatial grid and a 1-h time resolution drives IRI-2016 to generate ionospheric TEC values consistent with GNSS-TEC. For 2015 and 2019, the mean absolute error (MAE) of the modified IRI-TEC is improved by 78.57% and 77.42%, respectively, and the root mean square error (RMSE) is improved by 78.79% and 77.14%, respectively. The corresponding correlations of the linear regression between GNSS-TEC and the modified IRI-TEC are 0.986 and 0.966, more than 0.2 higher than with the standard IRI-TEC.

Highlights

(34.2◦ N/108.4◦ E), XZNM (31.8◦ N/87.2◦ E), and GXHC (24.7◦ N/108.1◦ E), to calculate IG-up values in accordance with the three time interpolation schemes introduced in Section 2.2 for 2015 and 2019, which are interpolated and plugged back into the International Reference Ionosphere (IRI)-2016 model to drive the calculation of total ionospheric electron content (TEC) time series with 1-min time intervals for comparison with the high-precision global navigation satellite systems (GNSS)-TEC results; see Section 2.3 for the evaluation method
It can be seen that the diurnal variation of the TEC estimated by IRI-2016 (IRI-TEC) is significantly different from that of GNSS-TEC, especially in the daytime, with a maximum difference of 20 TECu, and that IRI-TEC is more different from GNSS-TEC at middle latitudes than at low latitudes over China
From the data for 8–12 UT at station GXHC in Figure 3 and for 12–16 UT at station NMTK in Figure 4, it can be seen that when the TEC value becomes complex, the TEC results of schemes 2 and 3 exhibit obvious fluctuations compared with GNSS-TEC, while the TEC results of scheme 1 are consistent with GNSS-TEC

Summary

Introduction

It is an important part of the geospatial environment and has a significant impact on radio information systems such as global navigation satellite systems (GNSS), communication systems, and radar [1,2,3,4,5,6].

Methods

Results

Conclusion