Relative power spectra of IFLC and signal amplitude for four scintillation events during and before the geomagnetic storm. PRN = 30–7th represents the scintillation event that occurred at midnight on 7 September 2017, as marked by the black arrow in Figure 2, corresponding to the period of the most intense perturbation of near-earth space in Figure 1b. PRN = 09–8th represents the scintillation event that occurred on 8 September 2017, as marked by the red arrow in Figure 2. PRN = 09–5th-1 and PRN = 09–5th-2 represent the scintillation events on 5 September 2017 from 19:21 to 19:27 UT and 19:42 to 19:54 UT, respectively.