Abstract
The ionospheric medium is the primary source of error for signals from the Global Positioning System (GPS) satellites. Modeling ionospheric effects is one of the main challenges in developing accurate and reliable services for Space-Based Augmentation Systems. The Mapping Function (MF) and the estimation of the model coefficients are an essential parameter in the aspects of ionospheric modeling. In the present study, a Planar Fit (PF) model is considered to model the ionospheric Total Electron Content (TEC). The Ionosphere observations (GPS-TEC) obtained directly from the GPS receiver at Koneru Lakshmaiah Education Foundation (KLEF)-Guntur (16.44° N, 80.62° E) station and are used as reference values for comparison during the period 2015. The PF model is two-fold: first, the ionospheric line-of-sight TEC is converted into vertical TEC (vTEC) based on the Modified Mapping Function (MMF), and secondly, the PF coefficients are estimated based on the Gram–Schmidt Orthogonalization (GSO). The performance of the model is tested under quiet and disturbed ionosphere conditions and for different months of the year. The PF model values are in good agreement with the GPS-TEC values for the scenarios considered. The Average Absolute Error (AAE) and Root Mean Square Error (RMSE) values are maximum in equinoxes (March and October) and moderate in winter (January and December) and minimum in summer months (July and August). The PF model is adequate for characterizing the low-latitude ionospheric characteristics in different space weather conditions. The results would support towards the development of regional ionosphere models for navigation users under the GAGAN/NavIC system in India.
References
Bilitza, D.: International reference ionosphere 2000. Radio Sci. 36, 261–275 (2001)
Cander, L.R.: Ionospheric Space Weather, Springer Geophysics. Springer Nature, Switzerland AG (2019)
Dabbakuti, J.K., Mallika, Y., Rao, M.V., Rao, K.R., Ratnam, D.V.: Modeling of GPS-TEC using QR-decomposition over the low latitude sector during disturbed geomagnetic conditions. Adv. Space Res. 64, 2088–2103 (2019)
Dabbakuti, J.K., Ratnam, D.V., Sunda, S.: Modelling of ionospheric time delays based on adjusted spherical harmonic analysis. Aviation 20, 1–7 (2016)
Dyrud, L., Jovancevic, A., Brown, A., Wilson, D., Ganguly, S.: Ionospheric measurement with GPS: receiver techniques and methods. Radio Sci. 43, 1–11 (2008)
Golub, G.H., Van Loan, C.F.: Matrix Computations. Johns Hopkins University Press, Baltimore (2012)
Karanam, S., Ratnam, D.V., Dabbakuti, J.K.: Ionospheric time delay corrections based on the extended single layer model over low latitude region. Geodes. Geodynam. 10, 235–240 (2019)
Klobuchar, J.A.: Ionospheric time-delay algorithm for single-frequency GPS users. IEEE Trans. Aerosp. Electron. Syst. 23(3) 325–331 (1987)
Komjathy, A.: Global Ionospheric Total Electron Content Mapping Using the Global Positioning System. University of New Brunswick Fredericton, Canada (1997).
Langley, R.B.: Propagation of the GPS signals. In: GPS for Geodesy. Springer, Berlin (1996)
Ma, L., Han, Y., Yin, Z.: Periodicities in global mean TEC from GNSS observations. Earth Moon Planets 105, 3–10 (2009)
Misra, P., Enge, P.: Global Positioning System: signals, measurements and performance second edition, Global Positioning System: Signals. Measurements and Performance Second Editions 206 (2006)
Nava, B., Coisson, P., Radicella, S.: A new version of the NeQuick ionosphere electron density model. J. Atmos. Sol.-Terr. Phys. 70, 1856–1862 (2008)
Niranjan, K., Srivani, B., Gopikrishna, S., Rama Rao, P.V.S.: Spatial distribution of ionization in the equatorial and low-latitude ionosphere of the Indian sector and its effect on the pierce point altitude for GPS applications during low solar activity periods. J. Geophys. Res. 112, A05304 (2007)
NovAtel: GPStation-6 GNSS Ionospheric Scintillation and TEC Monitor (GISTM) Receiver User Manual, 2012
Prasad, N., Sarma, A.: Ionospheric time delay estimation using IDW grid model for GAGAN. J. Indian Geophys. Union 8, 319–327 (2004)
Rao, P.R., Jayachandran, P., Ram, P.S.: Ionospheric irregularities: the role of the equatorial ionization anomaly. Radio Sci. 32, 1551–1557 (1997)
Ratnam, D.V., Dabbakuti, J.K., Lakshmi, N.S.: Improvement of Indian-regional Klobuchar ionospheric model parameters for single-frequency GNSS users. IEEE Geosci. Remote Sens. Lett. 15, 971–975 (2018)
Ratnam, D.V., Dabbakuti, J.K., Sunda, S.: Modeling of ionospheric time delays based on a multishell spherical harmonics function approach. IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens. 10, 5784–5790 (2017)
Sarma, A., Prasad, N., Madhu, T.: Investigation of suitability of grid-based ionospheric models for GAGAN. Electron. Lett. 42, 478–479 (2006)
Schaer, S.: Mapping and predicting the earths ionosphere using the Global Positioning System, 205p. Ph. D. dissertation, University of Bern, Bern, Switzerland (1999)
Shukla, A., Sivaraman, M., Bandyopadhyay, K.: A comparison study of voxel based multi-and two-layer ionospheric tomography models over the Indian region using GPS data. Int. J. Remote Sens. 31, 2535–2549 (2010)
Shukla, A.K., Das, S., Nagori, N., Sivaraman, M., Bandyopadhyay, K.: Two-shell ionospheric model for Indian region: a novel approach. IEEE Trans. Geosci. Remote Sens. 47, 2407–2412 (2009)
Srinivas, V.S., Sarma, A., Achanta, H.K.: Modeling of ionospheric time delay using anisotropic IDW with Jackknife technique. IEEE Trans. Geosci. Remote Sens. 54, 513–519 (2016)
Sunda, S., Sridharan, R., Vyas, B., Khekale, P., Parikh, K., Ganeshan, A., Sudhir, C., Satish, S., Bagiya, M.S.: Satellite-based augmentation systems: a novel and cost-effective tool for ionospheric and space weather studies. Space Weather 13, 6–15 (2015)
Swamy, K., Sarma, A., Srinivas, V.S., Kumar, P.N., Rao, P.S.: Accuracy evaluation of estimated ionospheric delay of GPS signals based on Klobuchar and IRI-2007 models in low latitude region. IEEE Geosci. Remote Sens. Lett. 10, 1557–1561 (2013)
Walter, T., Hansen, A., Blanch, J., Enge, P., Mannucci, T., Pi, X., Sparks, L., Iijima, B., El-Arini, B., Lejeune, R., Hagen, M.: Robust detection of ionospheric irregularities. Navigation 48, 89–100 (2001)
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Pyla, R.K., Dabbakuti, J.R.K.K. Modeling of ionospheric TEC corrections based on modified mapping function and Gram–Schmidt orthogonalization at low latitude region. Astrophys Space Sci 365, 122 (2020). https://doi.org/10.1007/s10509-020-03830-5
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DOI: https://doi.org/10.1007/s10509-020-03830-5