1991 Volume 111 Issue 1 Pages 38-44
Simultaneous observations of the electric field intensity on the ground as well as optical observations of lightning flashes by VTR cameras have been performed in each one month from November to December for these five years in Kahoku-gata, a reclaimed flat land territory (4×5km in E-W and N-S directions) located in the northern suburbs of Kanazawa in winter. Polarity and approximate intensity of the electric field intensity on the ground have been obtained from continuous observation of the point corona discharge current. Regional distribution of the electric field is presumed by a graphical method on the basis of the time variations of those two quantities observed at six sites in the territory. On the other hand, lightning discharges occurred in the same territory have been recorded by several VTR cameras from two directions, three cameras observing from the east at Ishikawa College of Technology, other two from the north at Unoke fire department. These cameras were continuously operated for eight hours when thundercloud is forecasted to come over there.
Finally, the eleven accurate stroke points of the cloud-to-ground discharges were determined on the map. And it is found that the eleven stroke points are all located within the narrow band of ±1 km width including the boundary line between the positive and the negative domains of the electric field on the ground.