Observation of Multiple-Stroke Flashes through Electromagnetic Field

Abstract

Electric field changes associated with lightning discharges were observed by a network of fast antennas at Hokuriku area. These fast antennas were time-synchronized by GPS (Global Positioning System), which enabled location of individual return strokes. It turned out, that at least about. a half of negative multiple-stroke flashes had multiple terminations on the ground regardless of the seasons, and the distances between the terminating points were mostly within km. In winter, all the return strokes in positive multiple-stroke flashes had different terminations, and about 70%, of them were separated for more than 10km. The time intervals between successive return strokes in negative multiple-stroke flashes in winter were generally much shorter than those in summer.