# Correlation Study of Auroral Currents with External Parameters During 10-12 October 2024 Superstorm
## 3 Results
For example, the peak values of upward and downward FACs (red and blue dots) on the downside, duskside, and dayside of both hemispheres all occurred during the main phase of the geomagnetic storm, with the peaks in the Southern Hemisphere generally occurring earlier than in the Northern Hemisphere (except for the upward FACs on the downside and the FACs on the dayside, where the peaks in the Northern Hemisphere occurred earlier than in the Southern Hemisphere). The timing of peak upward and downward FACs also varied (except on the duskside and dayside of the Northern Hemisphere). During the nighttime, FACs mostly reached their peaks during the recovery phase of the storm (except for the upward FACs in the Southern Hemisphere). Thus, the timing when FACs attained peaks varied across local times and between two hemispheres. As the storm progressed, FACs initially shifted toward lower latitudes, and as the storm entered the recovery phase, they returned to higher latitudes. It is evident that the time when FACs reached their lowest latitude did not necessarily coincide with the minimum Dst value but rather occurred either during the main or recovery phase of the storm. For instance, on the downside and dusksides of both hemispheres, the lowest latitudes of upward and downward FACs (marked in brown and green, respectively) occurred during the main phase of the geomagnetic storm. On the dayside and nightside, the currents in the Northern Hemisphere appeared during the main phase (except for  
Figure 2: The storm-time and magnetic latitude (MLat) of peak upward and downward FACs per Swarm AC/B orbit. From top to bottom, the four local time sectors are dusk (**a**,**b**), dawn (**c**,**d**), daytime (**e**,**f**), and nighttime (**g**,**h**). The left panels (**a**,**c**,**e**,**g**) show data in the Northern Hemisphere and the right panels (**b**,**d**,**f**,**h**) in the Southern Hemisphere for 10–12 October 2024. The current densities are represented by the size of the circles. The upward and downward FACs are depicted in red and blue, respectively. The maximum upward and downward densities are marked by red and blue dots, respectively. The most equatorward MLat values of upward and downward FACs are indicated by brown and green dots, respectively. Additionally, the Dst index is shown in black. Storm-time represents hours starting at 0 UT on 10 October 2024.  
the downward FACs on the dayside, which occurred during the recovery phase), while in the Southern Hemisphere, the currents primarily occurred during the recovery phase (except for the downward FACs during the nighttime, which occurred during the main phase). Thus, the timing of FACs reaching the lowest latitude differed across local times and between the hemispheres. In summary, the variations in FAC density and latitude differed across local times and hemispheres, suggesting that the relevant highly correlated external factors may vary with local times and hemispheres. We calculated the average FAC density and latitude during the 12-48 storm-time period at various locations, with the results shown in Table 1. The 12-48 storm-time was chosen as it captures the period of intense FACs while minimizing influences of quiet-time conditions, as bracketed by two gray vertical dashed lines (see Figures 2 and 3). For the dawn-dusk sector, we distinguished between R1 and R2 currents, while on the dayside and nightside, we differentiated between peak upward and downward FACs due to the presence of multiple current sheets. In the study by [PERSON] and [PERSON] (1978) [PERSON] and [PERSON] (1978), it was reported that under relatively quiet conditions (AL \(>-100\) nT), the highest FAC densities occur near noon, with an average value of about 1.6 \(\upmu\)A/m\({}^{2}\). During more active periods (AL \(\leq-100\) nT), the peak current density regions shift toward the nightside, with the average current density increasing to approximately 2.2 \(\upmu\)A/m\({}^{2}\).