Preliminary Analysis of Ionospheric Responses to Geomagnetic Storms Using the BDS GEO Satellites

Abstract The rapid development of Global Navigation Satellite System (GNSS) provides a reliable way to monitor the ionospheric response of geomagnetic storms. Compared with other types of satellites, the advantage of using the Beidou Navigation Satellite System (BDS) Geostationary Earth Orbit (GEO) satellites to monitor the ionosphere is that it has almost fixed Ionospheric Pierce Points (IPPs). When using the GEO satellites to monitor the ionosphere, the earth sites only need consider the ionospheric temporal change without considering the spatial change. In addition, the ionospheric delay directly calculated by the combined observations does not introduce model error and fitting error, and can obtain continuous and high-precision ionospheric delay series. According to the Disturbance Storm Time index (DST index) provided by World Data Center for Geomagnetism of Kyoto, three large geomagnetic storms occurred in 2015. This article uses the BDS dual-frequency observations to calculate the ionospheric VTEC sequences during the geomagnetic storms at the four sites KZN2, JFNG, SIN1, and CUT0, respectively; and the ionospheric responses during the three large geomagnetic storms in 2015 are preliminarily analysed. The results show that the ionospheric responses to geomagnetic storms are mainly positive and negative anomalies. Combining the results of each site during three geomagnetic storms, it is certain that different seasons have a decisive impact on the positive and negative ionospheric responses of geomagnetic storms.