# Correlation Study of Auroral Currents with External Parameters During 10-12 October 2024 Superstorm
## 4 Discussion
### Correlation Analysis
The best correlation coefficient for each local time sector is specifically indicated in half gray bars. As shown in Figure 4, the correlation with IMF By is generally weak, suggesting that its influence on the local time and hemispherical differences in FAC peak density during  
Figure 4: The Spearman correlation study between FAC peak values and seven external parameters. (**a,c**) Northern Hemisphere (NH) and (**b,d**) Southern Hemisphere (SH). Different colors denote different local times. Brown and yellow are for duskside upward (J+) and downward FACs (**a,b**)) and for daytime upward and downward FACs (**c**), (**d**), respectively. [PERSON] and blue are for dawnside upward and downward FACs (**a,b**) and for nighttime upward and downward FACs (**c,d**). The strongest correlation coefficients are further indicated by half gray bars. geomagnetic storms is not significant. The correlation coefficients of Nsw and Vsw are both high, indicating that they play essential roles in the evolution of FACs during geomagnetic storms. For the northern duskside, Pd shows the best correlation with both upward and downward FAC peak density, while for the northern dawnside, Em shows the strongest correlation with FAC peak density. For the southern duskside, the upward FAC (R1 FACs) peak density has the strongest correlation with Em, while the downward FAC (R2 FACs) peak density is most strongly correlated with Dst. On the southern dawnside, Pd and Vsw show the best correlation with both upward and downward FAC peak density. On the dayside, Nsw and Pd (Pd) show the best correlation with FAC peak density in the Northern (Southern) Hemisphere, while on the nightside, Em shows the strongest correlation with FAC peak density. [PERSON] et al. (2005) [14] studied the 2003 Halloween storm and found that the dayside FACs were primarily correlated with Pd. In a subsequent study, [PERSON] et al. (2024) [10] examined the May 2024 storm and discovered that most of the dayside (nightside) FACs exhibited stronger correlations with Pd (Em or Pd). Comparing this with previous studies, it can be seen that during the October 2024 storm, the dayside FAC peak density was correlated predominantly with Pd (Nsw), while the nightside FAC peak density was correlated with Em, which is consistent with these earlier findings. This also explains why the FAC peaks on the dayside occurred primarily during the main phase of the storm, as Pd reached its peak during this phase. Similarly, it explains why the FAC peaks on the nightside were mainly observed during the recovery phase, as Em remained at a high level throughout the recovery period. The comparison with the May storm and previous superstorms suggests that the intensity of the dayside FACs was correlated with Pd, and the nightside FACs were correlated mainly with Em or Pd during geomagnetic storms, which should be a relatively general rule during superstorm periods. [PERSON] et al. (2024) [10] reported that dawnside FACs were most strongly correlated with Pd, while duskside FACs were most strongly correlated with Dst during the May 2024 storm. This seems to align with the present results in the south pole during this October storm but deviates from those in the north pole. In the October storm, Em correlates best with dawnside FACs in the north, while Pd correlates best with duskside FACs. In summary, the external correlation factors of FACs in the dawn and dusk sectors indeed vary from storm event to storm event. The Spearman correlation coefficients between the latitudes of peak FACs and seven external parameters are presented in Figure 5. It is evident that the latitudes of peak FACs on the dawnside-duskside show the strongest correlation with Em. In the Northern Hemisphere, the correlation with Em is most significant on the nightside, while on the dayside, the correlation with Pd is strongest. In the Southern Hemisphere, the latitudes of dayside upward FACs are most strongly correlated with Pd, while downward FACs on the dayside show the strongest correlation with IMF Bz.