Ionosphere disturbances on GNSS signal and positioning performance: Analysis of the solar flare and geomagnetic storm events in September 2017 and October 2021.

Ionosphere has important influences on the performances of Global Navigation Satellite System (GNSS) in terms of signal quality and ranging errors. This study discusses the impact of ionosphere disturbances caused by the solar flare and geomagnetic storm events in September 2017 and October 2021 on signal quality and positioning accuracy. To identify the occurrence and also to study the magnitude of the storm, we have evaluated the Solar Activity parameters and constructed global Rate of TEC Index maps. In regard of the GNSS signal, both the signal-in-space ranging error and cycle slip occurrence are adopted to study the influence of the solar flare on the accuracy of the broadcast ephemeris and the quality of phase observation. Furthermore, the kinematic precise point positioning experiments with 39 International GNSS Service (IGS) stations are carried out, and the positioning errors of north, east, and up components are calculated to assess the precise positioning accuracy during the storm. The presented results suggest that the kinematic precise point positioning accuracy of the selected IGS stations in low- and high-latitude areas degraded at 8th September 2017 and 12th October 2021, implying that the GNSS precise positioning are less reliable during the solar flare events. [ABSTRACT FROM AUTHOR]