Statistical Study of Magnetic impulse Events in Ground-Based Magnetic Records

Single Hall current loops in the ionosphere, produced by short-lived, 'impulse', charge injections into the E-region, produce unique signatures in the magnetic records at a ground-based site. We have developed a set of computer algorithms to automatically search magnetic records and to select impulsive magnetic events which satisfy predetermined criteria. The algorithms have been verified by visual scans of subsets of the data. We have concentrated on the impulsive changes in the vertical magnetic component. We report here the results of a statistical study of one year of data from the near-conjugate stations South Pole, Antarctica, and Iqaluit, Northwest Territories. The number of 'conjugate' events is largest for the local time (LT) interval 0800 to 1100. There is a sharp decrease in the number of events in the hour 1100-1200 LT.