# Effects of the October 2024 Storm over the Global Ionosphere
## 5 Discussion  
The present study focuses on the storm-induced global ionospheric response to the October 2024 storm, with the following impacts highlighted in Section 4. A storm-induced F-region uplift manifested as an increase in hmF2, observed on the dayside in both Hemispheres. This enhancement occurred while foF2 remained largely stable, except in the American longitude sector during the storm's early active phase. Conversely, a marked decrease in foF2, accompanied by uplift of the F-region, was detected on the nightside of the Southern Hemisphere during both the initial and main phases of the storm, as shown in Figures 3a-h and 4a-h. Certain nighttime longitude sectors displayed missing foF2 and hmF2 values during the storm period, highlighted by red rectangles in Figures 3a-h and 4a-h, a pattern also noted during the Mother's Day 2024 superstorm [6]. During the main and early recovery phases, extremely low hmF2 values were recorded over some isolated regions in the Southern Hemisphere's nightside sector, as indicated by regions A, B, and C in Figure 4. Section 4 attributes these to G-conditions, which are further illustrated in Figures 5a-h-7a-h, where COSMIC Ne profiles show foF1 exceeding foF2 and the F1 layer emerging as the Ne peak--most evident between 00:00 and 12:00 UT. The substantial F-region uplift during the storm is corroborated by strong vertical plasma drifts recorded at Eglin and Lualualualei in the Northern Hemisphere and Ascension Island in the Southern Hemisphere (Figure 8a). Swarm B data also indicated considerable Ne depletion over the dayside (Figure 10), implying that the F2 peak was over the observational range of COSMIC--2. The ionospheric response at high latitudes is initially driven by Joule heating, which raises upper thermospheric temperatures and accelerates neutral wind via ion drag. This heating initiates a global wind surge from polar to lower latitudes and into the opposite Hemisphere, often manifesting as a large-scale GW. This circulation creates midlatitude wind patterns, with GW and background wind representing complementary aspects of the same process. The surge, which favours the nightside and magnetically conjugate regions, is UT-dependent. Meanwhile, the thermospheric composition bulge--characterized by enhanced molecular nitrogen [N\({}_{2}\)] and reduced atomic oxygen [O]--is shaped by both background and storm-driven winds, not merely Earth's rotation. During geomagnetic storms, storm-time winds determine its location, while background winds modulate its diurnal variation during recovery. The rise in hmF2 is mainly due to equatorward wind that uplifts the F-region, while the drop in foF2, especially in sunlit areas, is tied to increased molecular nitrogen enhancing recombination and reducing Ne. These effects vary with local time and longitude, reflecting the spatial complexity of storm-time ionospheric responses. Increases in foF2--\"positive phases\"--typically occur on the dayside due to ionospheric uplift and equatorward plasma transport, known as the \"dayside ionospheric superfountain.\" These are driven by strong southward IMF, which induces a dawn-to-dusk electric field that promotes plasma convection. Though direct measurements are limited, models by [PERSON] (1969) [27] and [PERSON] et al. (1994) [28] support these mechanisms. On the nightside, low background ionization obscures positive phases, but dusk-time uplift can extend their effects. Negative phases, in contrast, are linked to the movement of the composition bulge and intensified thermospheric changes. This uplift matches the model proposed by [PERSON]--[PERSON] et al. (1994) [28], where meridional winds lift plasma and alter the composition. Global divergent winds also induce upwelling and redistribution of thermospheric species. Additional uplift may result from the equatorward expansion of the polar ionosphere and poleward EIA movement. [PERSON] et al.