## 5 Conclusions  
During this current study, we aimed to investigate the mid- and low-midlatitude ionospheric response to the 2024 Mother's Day superstorm. For this purpose, ground-based ionosonde measured F1, F2-layer, B0 and B1 parameters and isodensity data along with satellite measured electron density and O/N\({}_{2}\) ratio data were used. The main conclusions of our study are as follows:  
* A series of unique ionospheric conditions were determined by multi-instrumental observations and discussed in the current study. * A sudden and extreme decrease in the F2 layer electron density and a simultaneous uplift were detected with the Digisondes above SO and VT right after the SSC. The initial density decrease was mostly caused by the arrival of MIT to these latitudes. * Right after the end of the main phase, a peculiar G-condition developed in the ionosphere. This appears only during intense geomagnetic storms and is connected to extremely depleted plasma in the F2-layer. * Auroral F- and auroral Sporadic E-layers were observed at unprecedented low latitudes (42\({}^{\circ}\), 35\({}^{\circ}\) mlat, respectively) during the main phase, while the analyzed stations were below or near the AO. The first ever observation of auroral Es at SO occurred between 22:15-23:10 UT, while auroral F layers were recorded at SO (22:30-03:45 UT)and as extremely low latitude as VT station (22:37-03:52 UT) on 10/11 May 2024. Besides the optical observations and the Swarm measurements confirmed that the MIT, with the AO at its equatorward boundary, moved down as low as 35.9\({}^{\circ}\)N mlat. * The auroral and low-latitude nightside ionospheres converged at the MIT, creating an extraordinary situation where the midlatitude ionosphere was confined to the MIT itself. * Exceptionally prolonged disappearance of the ionospheric layers was observed through Digisonde measurements uniquely during daytime hours in the early recovery phase of the superstorm. The joint effect of the extremely decreased O/N\({}_{2}\) ratio and density, as well as along with the influence of DDEFs was the most probable cause of the disappearance and not the increased ionospheric absorption caused by the incident solar flares, which was confirmed by the amplitude method. * Three uplift phases were distinguished during the main and early recovery phases. The first phase was driven by global electric fields. The second phase was most likely caused by the spatially varying effect of storm-time winds and TIDs. While the decrease of the F1-layer height during the third uplift phase must have been driven by the westward DDEF. The underlying process responsible for the peculiar third-phase F2-layer uplift remains unclear and requires further investigation, involving additional observations from the plasmasphere. * The isodensity and virtual height (h'F, h'F2) data are most suitable for the investigation of the ionospheric layer height variations. * Effects of TIDs during geomagnetic storms are best observed with isodensity data. * The B0 parameter is sensitive to all the three types of ionospheric layer uplift (and overall, to geomagnetic storm effects), however, it is the most suitable for the indication of TID related ionospheric height variations. * In a future study, we plan to investigate the prolonged daytime disappearance of the F-layer and its anomalous 3 rd-phase uplift in detail, incorporating further experimental data and models like the thermosphere-ionosphere electrodynamic general circulation model (TIEGCM, see the article of [79; 80], and the Horizontal Wind Model 2007 (HWM07 [81; 82]). **Author Contributions:** [PERSON] was the main writer of the article, which contained the preparation of the event, manual scaling of ionosonde data, figure making and discussion of the results. [PERSON] helped in the manual scaling of VT data, in the preparation of the manuscript and reviewed the paper. [PERSON] gave ideas, made the figures from the Swarm data, wrote the paragraphs about the Swarm observations and reviewed the manuscript.