Occurrence ratios of the four types of scintillation events observed from the four Svalbard stations in Norway. For each station, the events from left to right represent: (1) phase indices, IFLC, and S₄ all show fluctuations; (2) both phase indices and S₄ show fluctuations, but not IFLC; (3) both phase indices and IFLC show fluctuations, but not S₄; (4) only phase indices show fluctuation, but not IFLC and S₄. Events before (5–6 September 2017) and during (7–8 September 2017) the geomagnetic storm are represented by blue and red colors, respectively.