Performance of ionospheric maps in support of long baseline GNSS kinematic positioning at low latitudes

Abstract

Ionospheric scintillation occurs mainly at high and low latitude regions of the Earth and may impose serious degradation on GNSS (Global Navigation Satellite System) functionality. The Brazilian territory sits on one of the most affected areas of the globe, where the ionosphere behaves very unpredictably, with strong scintillation frequently occurring in the local postsunset hours. The correlation between scintillation occurrence and sharp variations in the ionospheric total electron content (TEC) in Brazil is demonstrated in Spogli et al. (2013). The compounded effect of these associated ionospheric disturbances on long baseline GNSS kinematic positioning is studied in this paper, in particular when ionospheric maps are used to aid the positioning solution. The experiments have been conducted using data from GNSS reference stations in Brazil. The use of a regional TEC map generated under the CALIBRA (Countering GNSS high-Accuracy applications Limitations due to Ionospheric disturbances in BRAzil) project, referred to as CALIBRA TEC map (CTM), was compared to the use of the Global Ionosphere Map (GIM), provided by the International GNSS Service (IGS). Results show that the use of the CTM greatly improves the kinematic positioning solution as compared with that using the GIM, especially under disturbed ionospheric conditions. Additionally, different hypotheses were tested regarding the precision of the TEC values obtained from ionospheric maps, and its effect on the long baseline kinematic solution evaluated. Finally, this study compares two interpolation methods for ionospheric maps, namely, the Inverse Distance Weight and the Natural Neighbor.

Enhanced wide-area multi-GNSS RTK and rapid static positioning in the presence of ionospheric disturbances

“…Another approach, mainly applied in post-processing applications, utilizes GNSS-based global ionospheric maps (Zhang et al 2016). These maps, however, feature insufficient spatio-temporal resolution to capture the disturbances during high ionospheric activity (Park et al 2016). Analyzing the other possibilities it should be noted that the benefit from the application of ionosphere-free linear combination does not offset the drawback of providing a float-only solution.…”

Regional Short‐Term Forecasting of Ionospheric TEC and Scintillation

“…The proposed forecasting technique can be of interest for implementing real‐time mitigation algorithms of the ionospheric effect on GNSS precise positioning techniques, faced by mitigating scintillation. In Park et al (), an off‐line application of the proposed technique has been tested in long baseline RTK positioning over Brazil. The investigation has shown that TEC map obtained by applying this regional empirical model provides, on the average and under strong scintillation, an improvement of 40.4% over the GIM TEC map in terms of positioning accuracy for the kinematic positioning performance.…”

“…Radio Science thin shell at an altitude of 350. The thin shell approximation has been chosen since it guarantees a fast computation and a quite accurate description of the ionosphere from a positioning point of view (Park et al, 2016(Park et al, , 2017.…”

“…With the receiver position (in Earth‐centered Earth‐fixed coordinates) available from the RINEX observation file and the satellite positions estimated from RINEX navigational files, positions of each ionospheric pierce point (IPP) have been calculated considering the ionosphere as a thin shell at an altitude of 350. The thin shell approximation has been chosen since it guarantees a fast computation and a quite accurate description of the ionosphere from a positioning point of view (Park et al, , ).…”

Neural network based model for global Total Electron Content forecasting

“…Development of proper ionospheric forecasting solutions further complicates not only because helio-geophysical disturbances alter the "regular" properties and dynamics of the ionospheric plasma, but also because the users demanding for their implementation in real-time to support a variety of needs, e.g. for mitigating the ionospheric effects of space weather on modern technological infrastructures relying on space-based navigation systems (Cesaroni et al, 2015;Park et al, 2016). Accordingly, efforts are continuously devoted to upgrade the so-called "climatological models", able to provide median features of, e.g., the ionospheric electron density profile, to the real-time weather predictions.…”