Precise Ionosphere Modeling Using Regional GPSNetwork Data

Y. Gao, Z.Z. Liu

Department of Geomatics Engineering The University of Calgary Calgary, Alberta, Canada.

DOI:                 

Abstract

The ionosphere affects the electromagnetic waves that pass through it by inducing an additional transmission time delay. The ionosphere influence has now become the largest error source in GPS positioning and navigation after the turn-off of the Selective Availability (SA). In this paper, methods of 2D grid-based and 3D tomography-based ionospheric modeling are developed based on regional GPS reference networks. Performance analysis was conducted using data from two different regional GPS reference networks. The modeling accuracy of the vertical TEC (VTEC) is at the level of several TECU for 2D ionospheric modeling and about one TECU for 3D tomographic modeling after a comparison to independent ionospheric map data or directly measured ionospsheric TEC values. The data analysis has indicated that the modeling accuracy based on the 3D tomography method is much higher than the 2D grid-based approach.

Keywords

GPS, Ionosphere, Ionosphere Grid, Tomography

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Coster, A.J., E.M. Gaposchkin and L.E. Thornton (1992). Real-Time Ionospheric Monitoring System Using GPS. Navigation, Journal of Institute of Navigation, Vol.39, No.2, pp.191-204.
[2]	El-Arini, M.B., C.J. Hegarty, J.P. Fernow and J.A. Klobuchar (1994). Development of an Error Budget for a GPS Wide-Area Augmentation System (WAAS), Proceedings of The Institute of Navigation National Technical Meeting, San Diego, CA, January, 1994.
[3]	El-Arini, M.B., R.S. Conker, T.W. Albertson, J.K. Reagan, J.A. Klobuchar and P.H. Doherty (1995). Comparison of Real-Time Ionospheric Algorithms for a GPS Wide-Area Augmentation System (WAAS). Navigation, Journal of The Institute of Navigation, Vol.41, No.4, pp.393-412.
[4]	FAA (1997). Specification for the Wide Area Augmentation System, FAA-E-2892C (draft), 1997.
[5]	Fedrizzi, M., R.B. Langley, A. Komjathy, M.C. Santos, E.R. de Paula and I.J. Kantor (2001). The Low-Latitude Ionosphere: Monitoring its Behavior with GPS, Proceedings of ION GPS 2001, 14th International Technical Meeting of the Satellite Division of the Institute of Navigation, Salt Lake City, UT, September 11-14, 2001.
[6]	Gao, Y., P. Heroux and J. Kouba (1994). Estimation of GPS Receiver and Satellite L1/L2 Signal Delay Biases Using Data from CACS, Proceedings of KIS-94, Banff, Canada, August 30 - September 2, 1994.
[7]	Gao, Y., X. Liao and Z.Z. Liu (2002). Ionosphere Modeling Using Carrier Smoothed Ionosphere Observations from a Regional GPS Network, Geomatica, Vol. 56, No.2, pp. 97-106
[8]	Howe, B.M. (1997). 4-D Simulations of Ionospheric Tomography, Proceedings of ION National Technical Meeting, Santa Monica, California January 14-16, 1997.
[9]	Jakowski, N., E.Sardon and S. Schlüter (1998). GPS based TEC Observations in Comparison with IRI95 and the European TEC Model NTCM2, Advances in Space Research, Vol. 22, pp.803-806.
[10]	Klobuchar, J.A. (1987). Ionospheric Time-Delay Algorithm for Single-Frequency GPS Users, IEEE Transactions on Aerospace and Electronic Systems, Vol. AES-23, No.3, pp.325-331.
[11]	Komjathy, A. (1997). Global Ionospheric Total Electron Content Mapping Using the Global Positioning System, Ph.D. dissertation, Department of Geodesy and Geomatics Engineering Technical Report NO. 188, University of New Brunswick, Fredericton, New Brunswick, Canada, 248pp.
[12]	Liao, X. (2000). Carrier Phase Based Ionosphere Recovery Over A Regional Area GPS Network, UCGE Reports, Number 20143, University of Calgary, Calgary, Alberta, Canada, pp120.
[13]	Liu, Z.Z. and Y. Gao (2001a). Optimization of Parameterization in Ionospheric Tomography, Proceedings of ION GPS 2001, Salt Lake City, Utah, USA, September 11-14, 2001.
[14]	Liu, Z.Z. and Y. Gao (2001b). Ionospheric Tomography Using GPS Measurements, Proceedings of KIS-2001, Banff, Alberta, Canada, June 5-8, 2001.
[15]	Raymund, T.D. (1995). Comparisons of Several Ionospheric Tomography Algorithms, Ann. Geophys., 13, pp. 1254-1262.
[16]	Raymund, T.D., J.R. Austen, S.J. Franke, C.H. Liu, J.A. Klobuchar and J. Stalker (1990). Application of Computerized Tomography to the Investigation of Ionospheric Structures, Radio Science, 25, pp. 771-789.
[17]	Raymund, T.D., Y. Bresler, D.N. Anderson and R.E. Daniell (1994). Model-assisted Ionospheric Tomography: A New Algorithm, Radio Science, 29, pp. 1493-1512.
[18]	SCIGN (2002). Southern California Integrated GPS Network, http://www.scign.org, accessed on April 1st, 2002.
[19]	Schaer, S. (1999). Mapping and Predicting the Earth’s Ionosphere Using the Global Positioning System, Ph.D dissertation, Astronomical Institute, University of Berne, Switzerland, pp205.
[20]	Skone, S. (1998). Wide Area Ionosphere Grid Modeling in the Auroral Region. UCGE Reports Number 20123, Ph.D thesis, The University of Calgary, Calgary, Alberta, Canada.
[21]	Walker, J.K. (1989). Spherical Cap Harmonic Modeling of High Latitude Magnetic Activity and Equivalent Sources with Sparse Observations, Journal of Atmospheric and Terrestrial Phy