Relationship between solar wind parameters and magnetic activity in the near-pole region: Application to space weather forecasting Original Research Article

We studied the relationship between solar wind and geomagnetic disturbances in the near-pole region using the polar cap index (PC) at Thule and WIND satellite data. The results of the analyses showed that the PC index is saturated when the merging electric field (Em) is high (more than 5 mV/m) and that the PC index is enhanced by the effect of the DP 1 current system. Further, the Em and the PC index show a good correlation with energy injection rate Q. This result suggests that ring current development can be estimated from the PC index as well as from the Em. Therefore, the real-time PC index is useful for monitoring the magnetospheric electric field and nowcasting and forecasting geomagnetic storms.