Statistical analysis between SuperMAG-based indices and AE, PC indices in the development of the storm-time ring current

Abstract:

To investigate the dependence of partial ring current in developing ring current, SMR LT (SMR-00, SMR-06, SMR-12, SMR-18) indices provided by SuperMAG were analyzed during magnetic storm periods. Especially, to understand solar activity effects, they were divided into solar maximum period and solar minimum period. As a result, more than 100 magnetic storms were examined with the magnetic storm size. Storms are divided into three categories in terms of the minimum value of the Dst index, Dstmin: severe(Dstmin<-200 nT), intense(-200 nT ≤Dstmin <-100 nT), moderate(-100 nT≤Dstmin<-50 nT). Regardless of storm size and the degree of solar activity, the average value of SMR-18 is among the highest and that of SMR-06 is lowest during magnetic storms. The correlation coefficient between the average value of SMR and that of SMR-18 was also higher than that of SMR versus SMR-06. This results means that the intensity of partial ring current in developing the ring current is stronger in the dusk sector than in dawn sector. For the severe storms, unusually, there is no difference between the average value of SMR-18 and that of SMR-00. Though the number of severe storm is a few in this study, it may mean the currents related to SMR-00 also have an important role in developing severe magnetic storms. Thus, the effect of SMR-18 in developing storm-time ring current decreases as the storm size increases. During recovery phase of magnetic storms, the shape of ring current is nearly symmetric. To compare the appearance of magnetic storms during recovery phase, SuperMAG-based indices and official auroral electrojets indices were compared. And, the SuperMAG-based indices and PC indices were also compared during magnetic storm period.