Earth Current at Kanoya and Oceanic Tide
Shiraki, M. & Tanaka, Y.
Abstract
Geomagnetic lunar daily variation is very small compared with the solar one. This relation is expected a1so for the daily variation of earth current induced by the geomagnetic variation. However, the observed lunar variation of earth current at Kanoya (31°25'N，130°54'E) is larger than the solar one. This fact may be explained by earth current due to oceanic tide. In this case spectral peaks in the earth current at Kanoya may be found corresponding to those in tidal spectrum. With this presupposition the spectral stracture of NS component of earth current at Kanoya was calculated and compared with the tidal constants at Kagoshima (31°36'N， 130°34'E) and Aburatsu (31°35'N， 131°25'E). Magnitudes of detected peaks in earth current spectrum cannot be explainable by the usual electromagnetic induction effect of the geomagnetic variation as it is supposed, but it may be explained by the tidal origin. The effect of oceanic tide on the earth current at Kanoya is fairly large for the solar daily variation as well as the lunar one.
