Comparison of planetary and local geomagnetic disturbance indices: Operational implications

Geomagnetic storms can disrupt social infrastructure on Earth; thus, accurate and timely monitoring is required to reduce their future socioeconomic impact. This study compares the planetary geomagnetic disturbance index (KP) with local indices at Fredericksburg (FRD) and Kakioka (KAK) stations. Local K indices at KAK and Cheongyang (CYG) are estimated and validated using indices observed at both stations. We found generally similar correlations between the KP index and the local K indices at FRD and KAK; however, their details differ. The results show that, even when planetary geomagnetic storms are observed, the local K can be smaller than the observed KP. This implies that both KP and local K should be simultaneously monitored. Real-time estimation of local K shows that the estimated K at KAK and CYG correlates well with the observed K. The estimation probability at KAK and CYG, with an error range of ±1, is greater than 98% when the local K is greater than 3. This suggests that the estimation approach used in this study can be operationally applied for timely monitoring of local geomagnetic disturbances.