Ionospheric Behavior during the 10 June 2021 Annular Solar Eclipse and Its Impact on GNSS Precise Point Positioning

Abstract

The main effects of the 10 June 2021 annular solar eclipse on GNSS position estimation accuracy are presented. The analysis is based on TEC measurements made by 2337 GNSS stations around the world. TEC perturbations were obtained by comparing results 2 days prior to and after the day of the event. For the analysis, global TEC maps were created using ordinary Kriging interpolation. From TEC changes, the apparent position variation was obtained using the post-processing kinematic precise point positioning with ambiguity resolution (PPP-AR) mode. We validated the TEC measurements by contrasting them with data from the Swarm-A satellite and four digiosondes in Central/South America. The TEC maps show a noticeable TEC depletion (<−60%) under the moon’s shadow. Important variations of TEC were also observed in both crests of the Equatorial Ionization Anomaly (EIA) region over the Caribbean and South America. The effects on GNSS precision were perceived not only close to the area of the eclipse but also as far as the west coast of South America (Chile) and North America (California). The number of stations with positioning errors of over 10 cm almost doubled during the event in these regions. The effects were sustained longer (∼10 h) than usually assumed.

IonosphericTotal Electron Content Changes during the 15 February 2018 and 30 April 2022 Solar Eclipses over South America and Antarctica

“…Our study of PSE2018 and PSE2022 is based partially on the methodology described in [2,34,57]. We used the approach proposed in [35] to determine the eclipse masks at 350 km ionospheric height.…”

“…Then, we used 507 and 398 GPS stations used in PSE2018 (see Figure 1 left panel) and PSE2022 (see Figure 1 right panel), respectively. Additionally, we use differential VTEC (DVTEC in TECu and %) to analyze ionospheric irregularities, as shown in Equations ( 1) and ( 2) [34,57,61].…”

“…The trajectories of an eclipse can differ geographically and temporally depending on the observing altitude chosen, which could be important for researching ionospheric dynamics. Research has shown the importance of estimating the eclipse mask at the height of the ionosphere to be studied and not only working with the mask at the surface level [33][34][35].…”

Ionosphere Monitoring with Remote Sensing

“…In this context, Gao et al [58] developed a monitor to clearly detect anomalies with an average detection speed improved by more than 16% when dealing with real data instead of simulations. Valdés-Abreu et al [59] studied the effects of an annular solar eclipse on GNSS position estimation accuracy based on TEC measurements performed by over 2000 stations worldwide, which were validated with measurements by the Swarm satellite mission and four digisondes in Central and South America. In particular, TEC maps pointed out a TEC depletion under the moon's shadow and important variations in both crests of the Equatorial Ionization Anomaly (EIA).…”

“…Variations typically affect the amplitude of the signal and its delay (see Bravo et al [60] and references therein) and can affect regions outside the umbra and penumbra of the eclipse [61][62][63]. With this global coverage, the work of Valdés-Abreu et al [59] allowed them to find other locations in the world that could be affected by perturbations in the North Pole and infer how that perturbations propagate to those potential locations.…”