Sparse Reconstruction of the Ionosphere in the Equatorial Anomaly Region During the Solar Eclipse Based on Beidou Ground Based Augmentation System

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Computerized Ionospheric Tomography (CIT) is a technique to reconsruct the ionosphere based on the slant total electron content (STEC) on the path between satellites and stations. It is of great significance for the study of the temporal and spatial characteristics of the ionosphere and the monitoring of abnormal characteristics. The solar eclipse that occurred on June 21, 2020 provides an opportunity to study the impact of the solar eclipse on the ionosphere in the equatorial anomaly region, and provides an opportunity for further research on the impact of ionospheric changes on high-precision positioning. This paper uses data from the Beidou Ground Based Augmentation System (BDGBAS) and some overseas IGS stations to study the impact of the solar eclipse on the ionosphere in the low-latitude equatorial ionization anomaly (EIA) region. In order to better deal with the problems of sparse observations and uneven distribution, a tomographic sparse imaging method driven by compressed sensing fusion data-driven method was used to realize the three-dimensional electron density in EIA region under solar eclipse and non-eclipse states. The results show that there is a significant decrease in electron density and TEC during a solar eclipse compared to a non-eclipse period. The most obvious electron density and TEC depletion occur in the EIA peak area, and the TEC value decreases as much as 6–10 TECUs, accounting for 30–40% of non-eclipse states. With the pass of the solar eclipse, the electron density and TEC decrease also tend to gradually increase and then decrease. In addition, it was observed that the electron density increased during the solar eclipse, leading to the enhancement of TEC in some EIA regions, which was consistent with the prediction results of other literature. Compressed sensing fusion data-driven tomography method plays an important role in the study of ionospheric disturbances caused by solar eclipses and the impact of ionospheric changes during solar eclipses on high-precision positioning. The ionospheric tomography model based on the BDGBAS is of great significance to the fields of accurate ionospheric monitoring and abnormal warning.