Modeling and optimization of ionospheric model coefficients based on adjusted spherical harmonics function

Abstract The range error caused by ionospheric delay in Global Positioning System (GPS) signals is currently the main factor that affected the positioning accuracy and navigation determination. Ionospheric modeling and optimization of its range error is a practical approach to improve the GPS positioning accuracy. The global ionospheric models are mostly unable to predict ionospheric delay corrections over the India region due to the Equatorial Ionization Anomaly (EIA)/fountain effect and lack of equatorial/low latitude GPS stations data. This paper proposes a method to facilitates regional ionospheric delay corrections based on the Adjusted Spherical Harmonic Function (ASHF) model by considering fewer coefficients into the algorithm. The ionospheric correction is driven with low-resolution harmonics coefficients with order ≤2 (≤9 coefficients), and coefficients are estimated with the Modified Gram-Schmidt (MGS) approach. The performance of the proposed model (ASHF) is compared with the Spherical Harmonic Function and Klobuchar models. Preliminary results reveal that the low-resolution ASHF model improved the ionospheric time delay corrections by 12.98% relative to the Klobuchar model. The results could be useful in the context of ionospheric time delay modeling for regional navigation satellite systems.

[1]  Gang Wang,et al.  Evaluation of COMPASS ionospheric model in GNSS positioning , 2013 .

[2]  S. Panda,et al.  Ionospheric total electron content response to September-2017 geomagnetic storm and December-2019 annular solar eclipse over Sri Lankan region , 2021 .

[3]  A. D. Sarma,et al.  Investigation of suitability of grid-based ionospheric models for GAGAN , 2006 .

[4]  S. Panda,et al.  Singular spectrum analysis of GPS derived ionospheric TEC variations over Nepal during the low solar activity period , 2020 .

[5]  D. Venkata Ratnam,et al.  Improvement of Indian-Regional Klobuchar Ionospheric Model Parameters for Single-Frequency GNSS Users , 2018, IEEE Geoscience and Remote Sensing Letters.

[6]  Sandro M. Radicella,et al.  A new version of the NeQuick ionosphere electron density model , 2008 .

[7]  Rimantas Kacianauskas,et al.  Determining the shape of agricultural materials using spherical harmonics , 2016, Comput. Electron. Agric..

[8]  Jianhua Zhou,et al.  Evaluation of COMPASS ionospheric grid , 2014, GPS Solutions.

[9]  Kutubuddin Ansari,et al.  Empirical orthogonal function modelling of total electron content over Nepal and comparison with global ionospheric models , 2020, Acta Astronautica.

[10]  Kutubuddin Ansari,et al.  Investigation of equatorial plasma bubble irregularities under different geomagnetic conditions during the equinoxes and the occurrence of plasma bubble suppression , 2020 .

[11]  W.A. Feess,et al.  Evaluation of GPS Ionospheric Time-Delay Model , 1987, IEEE Transactions on Aerospace and Electronic Systems.

[12]  J R K Kumar Dabbakuti,et al.  Modeling of GPS-TEC using QR-decomposition over the low latitude sector during disturbed geomagnetic conditions , 2019, Advances in Space Research.

[13]  J R K Kumar Dabbakuti,et al.  Modeling and analysis of ionospheric TEC variability from GPS–TEC measurements using SSA model during 24th solar cycle , 2021 .

[14]  J. R. K. Kumar Dabbakuti,et al.  Modeling of Ionospheric Time Delays Based on a Multishell Spherical Harmonics Function Approach , 2017, IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing.

[15]  S. Panda,et al.  Analysis of ionospheric TEC from GPS, GIM and global ionosphere models during moderate, strong, and extreme geomagnetic storms over Indian region , 2019, Acta Astronautica.

[16]  J R K Kumar Dabbakuti,et al.  Ionospheric and plasmaspheric electron contents from space-time collocated digisonde, COSMIC, and GPS observations and model assessments , 2021 .

[17]  A. Singh,et al.  Anomaly effects of 6–10 September 2017 solar flares on ionospheric total electron content over Saudi Arabian low latitudes , 2020 .

[18]  Rimantas Kačianauskas,et al.  Investigation of symmetric non-spherical particle shapes by applying low-resolution spherical harmonics , 2017 .

[19]  Jens Berdermann,et al.  Ionospheric correction using NTCM driven by GPS Klobuchar coefficients for GNSS applications , 2017, GPS Solutions.

[20]  Saurabh Das,et al.  Approach for near-real-time prediction of ionospheric delay using Klobuchar-like coefficients for Indian region , 2013 .

[21]  P. T. Jayachandran,et al.  Ionospheric irregularities: The role of the equatorial ionization anomaly , 1997 .

[22]  Álvaro Ramírez-Gómez,et al.  Low-resolution spherical harmonics models in application to quasi-quadric particle shapes , 2016 .

[23]  P. Jamjareegulgarn.  Assessment of bottomside thickness parameters over magnetic equator and low latitudes during high solar activity of solar cycle 24 , 2020 .

[24]  J. R. K. Kumar Dabbakuti,et al.  Evaluation of Ionospheric Delays Based on Orthogonal Dimensionality Reduction Approach , 2021 .

[25]  N. Kubo,et al.  Linear time-series modeling of the GNSS based TEC variations over Southwest Japan during 2011–2018 and comparison against ARMA and GIM models , 2019 .

[26]  Torben Schüler,et al.  GNSS single frequency ionospheric range delay corrections: NeQuick data ingestion technique , 2012 .

[27]  S. Panda,et al.  Empirical Orthogonal Function analysis and modeling of ionospheric TEC over South Korean region , 2019, Acta Astronautica.

[28]  Yang Zhang,et al.  A Novel Architecture to Eliminate Bottlenecks in a Parallel Tiled QRD Algorithm for Future MIMO Systems , 2017, IEEE Transactions on Circuits and Systems II: Express Briefs.

[29]  R. Grenfell,et al.  Refining the Klobuchar ionospheric coefficients based on GPS observations , 2008, IEEE Transactions on Aerospace and Electronic Systems.

[30]  J. Klobuchar.  Ionospheric Time-Delay Algorithm for Single-Frequency GPS Users , 1987, IEEE Transactions on Aerospace and Electronic Systems.

[31]  Kiran Kumar Anumandla,et al.  Implementation of storm‐time ionospheric forecasting algorithm using SSA–ANN model , 2020, IET Radar, Sonar & Navigation.

[32]  J R K Kumar Dabbakuti,et al.  Modelling of ionospheric time delays based on adjusted spherical harmonic analysis , 2016 .

[33]  Kefei Zhang,et al.  Regional ionospheric TEC modeling based on a two-layer spherical harmonic approximation for real-time single-frequency PPP , 2019, Journal of Geodesy.

[34]  Yidan Huang,et al.  Improving Klobuchar Type Ionospheric Delay Model using 2D GPS TEC over China , 2006 .

[35]  Ashish K. Shukla,et al.  Two-Shell Ionospheric Model for Indian Region: A Novel Approach , 2009, IEEE Transactions on Geoscience and Remote Sensing.