On Earth-current at Kakioka and Toyohara

[摘要] This paper is a brief preliminary report of earth-current observed at Kakioka and Toyohara from Aug. 1932 to Aug. 1933, the 2nd polaryear. Comparing records at both places, we have found a striking similarity in spite of their geographical and geological differences. The diurnal variation curve has two maxima at 4h a. m. and 2h p. m., and at Kakioka, the east-and north-components have mean ranges of 0.78 and 0.50 millivolts per 100m respectively, while at Toyohara, 0.73 and 0.29 millivolts. It is interesting that the general direction of diurnal variation is SW-NE, approximately directing to the magnetic northpole as at some other places in the world. We try to explain a pretty large variation in earth-current accompanied by thunderstorm or shower, but earth-magnetism does not so large variations. By a simple calculation, it was found that this current does not flow deeper than 800m beneath the earth surface, supposing a mean resistivity of the soil is 104 ohms per cm.

[学科分类] 大气科学