Klobuchar, NeQuickG, BDGIM, GLONASS, IRI-2016, IRI-2012, IRI-Plas, NeQuick2, and GEMTEC Ionospheric Models: A Comparison in Total Electron Content and Positioning Domains

Abstract

Global navigation satellite systems (GNSS) provide a great data source about the ionosphere state. These data can be used for testing ionosphere models. We studied the performance of nine ionospheric models (Klobuchar, NeQuickG, BDGIM, GLONASS, IRI-2016, IRI-2012, IRI-Plas, NeQuick2, and GEMTEC) both in the total electron content (TEC) domain—i.e., how precise the models calculate TEC—and in the positioning error domain—i.e., how the models improve single frequency positioning. The whole data set covers 20 years (2000–2020) from 13 GNSS stations, but the main analysis involves data during 2014–2020 when calculations are available from all the models. We used single-frequency positioning without ionospheric correction and with correction via global ionospheric maps (IGSG) data as expected limits for errors. Improvements against noncorrected solution were as follows: GIM IGSG—22.0%, BDGIM—15.3%, NeQuick2—13.8%, GEMTEC—13.3%, NeQuickG and IRI-2016—13.3%, Klobuchar—13.2%, IRI-2012—11.6%, IRI-Plas—8.0%, GLONASS—7.3%. TEC bias and mean absolute TEC errors for the models are as follows: GEMTEC—−0.3 and 2.4 TECU, BDGIM—−0.7 and 2.9 TECU, NeQuick2—−1.2 and 3.5 TECU, IRI-2012—−1.5 and 3.2 TECU, NeQuickG—−1.5 and 3.5 TECU, IRI-2016—−1.8 and 3.2 TECU, Klobuchar—1.2 and 4.9 TECU, GLONASS—−1.9 and 4.8 TECU, and IRI-Plas—3.1 and 4.2 TECU. While TEC and positioning domains differ, new-generation operational models (BDGIM and NeQuickG) could overperform or at least be at the same level as classical empirical models.

Ionospheric Error Models for Satellite-Based Navigation—Paving the Road towards LEO-PNT Solutions

“…Therefore, it is crucial to mitigate its impacts by modelling its effects. There are several existing models in the literature that aim to mitigate ionospheric delays, such as the NeQuick, Klobuchar, BeiDou Global broadcast Ionospheric delay correction Model (BDGIM), and Quasi-4-Dimension Ionospheric Modeling (Q4DIM) models [23]. These models measure or predict the error induced by the ionosphere, depending on the user's location, time of day, and day of the year [24,25].…”

“…Contrary to DFRs, SFRs rely on two widely used models to estimate ionospheric delay, namely the Klobuchar [23][24][25] and NeQuick [23,25] models. The first is typically used in GPS and BeiDou, while the latter is more encountered in Galileo signals.…”

“…Additional ionospheric models also include IRI, NeQuick2, IGS, BDGIM, etc. [23,39]. Choosing an adequate ionospheric model generally depends on many factors, including real-time availability and computational complexity.…”

“…The Klobuchar model was the first model developed to provide ionospheric correction through GPS signals. It is designed to be a computationally lightweight model while delivering a 50% decrease in the Root Mean Square (RMS) of the positioning error [23][24][25]. The algorithm, which runs on GNSS receivers, determines the ionospheric delay based on several parameters, such as the user's approximate geodetic latitude and longitude, elevation and azimuth angles of the visible satellites, and eight coefficients pα i , β i ; i " 0, .…”

Advances in GNSS Positioning and GNSS Remote Sensing

“…Research addressing the three aspects mentioned above will greatly promote the application of real-time high-precision GNSS positioning in the mass market and advance autonomous driving and urban digitization. This Special Issue, entitled “ Advances in GNSS Positioning and GNSS Remote Sensing” in Sensors ( , (accessed on 2 February 2024)), attracted 10 articles [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ] on new GNSS techniques for ionospheric studies, the impact of space weather on GNSS and methods for precise navigation.…”