## 6 Summary and Concluding Remarks  
This paper investigates the high-latitude ionosphere dynamics in terms of irregularity formation triggered by the intense solar event of 8 September 2017. It adopts a multi-observation approach combining information from TEC spatial-temporal variation and scintillation parameters, with measurements acquired by the SSUSI instrument on board the DMSP satellites, SuperDARN, Swarm spacecraft and ground-based magnetometers. The proposed investigation, together with the integration of the large variety of data used, allows for the collocation the observed amplitude and phase scintillations with a highly perturbed ionosphere characterized by strong variability of plasma dynamics and intense ionization. In this storm, indeed, the ionization enhancement due to the intense particle precipitation during periods of strong southward \(B_{\mathrm{z,IMF}}\) is added to the ionization due to both flares and solar proton events with energies greater than 10 MeV [52; 53]. Consequently, SED plume, TOI and PCP developed, as highlighted by both high TEC values and the electron density increases measured in situ by Swarm satellites. In addition, both the GNSS receivers located at SANAE IV and Concordia stations recorded vertical TEC values much higher than during quiet times, which exceeded 20 TECu, concurrent with amplitude and phase scintillation events. Such local vertical TEC increases induced a locally large variability of the plasma dynamics as confirmed by both the geomagnetic field variations, recorded at ground by magnetometers co-located with GNSS receivers,  
Figure 13: Polar-view maps in AACGM latitude and MLT of SuperDARN observations at 15:00 UT (**a**), 15:10 UT (**b**), 15:20 UT (**c**) and 15:30 UT (**d**) on 8 September 2017. Each map shows the isocontours of the ionospheric potential (red = positive, blue = negative potential) and the location of SuperDARN measurements (black squares) recorded in the two minutes following the time shown at the top of each map. In each map the projection to 350 km of altitude of all the \(\sigma_{\varphi}\) values having elevation angle \(\alpha\) = 30\({}^{\circ}\) (purple circles), recorded by the GNSS receiver at Concordia in the same time interval as for SuperDARN observations are also shown. In each map, which covers 00:00–24:00 MLT and \(|\) 50\({}^{\circ}\) \(|\) = 90\({}^{\circ}\) \(|\) AACGM Lat, the magnetic noon/midnight is at the top/bottom. and the comparison among scintillation parameters, ROT and electron density variations measured in situ by Swarm satellites. Specifically, in the same time interval as for amplitude scintillations, both the magnetometers at SANAE IV and Concordia recorded simultaneous variations of both the \(H\) and \(Z\) components of the geomagnetic field, highlighting the quick succession inside the field of view of the GNSS receivers of ionospheric currents of varying intensity. In addition, in conjunction with moderate/intense phase and amplitude scintillations, large increases of electron density _rms_ occurred simultaneously with the greatest ROT excursions. Since _rms_ is an estimation of the mean value of the electron density and ROT supplies information about the TEC rate of change, the simultaneity among ROT excursion, electron density _rms_ variation between two consecutive orbits and GNSS scintillations confirms the high variability of the plasma dynamics and the association of the observed scintillation with such variability. The ionospheric scenario depicted by the proposed multi-observation approach results in an uneven electron density distribution. As shown in vertical TEC maps (Figures 5 and 11), several gradients populated the investigated regions, confirming the presence of plasma variability.