Abstract
The exact locations of 52 ground flash points of winter lightning were determined by VTR images taken from two observation sites. These optical observations of lightning flashs by VTR cameras had been carried out for about 40 days from November to December every year from 1985 to 1992 in Kahoku-Gata, a reclaimed flat land situated in the northern suburbs of Kanazawa, Japan. This land lays close to the Sea of Japan. Two kinds of meteorological radar echo diagrams are obtainable in this district, one being recorded by the Tojimbo radar of Meteorological Agency and the other by the Hotatsu-San radar of Ministry of Construction. The former is located at about 70km southwest and the latter at about 20km northeast of Kahoku-Gata. It is pointed out as a conspicuous feature that positions of the 52 ground flash points are all found on fringe of radar echo patterns obtained by the Tojimbo radar. As for 29 cases among them, the radar echo diagrams observed simulta-neously by both radar sites have been obtained. The echo distributions in the corresponding two echo-diagrams are similar to each other, but the details are different. Nevertheless, the ground flashes around Kahoku-Gata occurred on the fringe of radar echo patterns. Thus, when edge of the radar echo approaches to the important substation sites or transmission routes, any lightning flash to the ground might strike those power apparatus.
