On the Diurnal Variation of the Earth's Magnetic Field (First Report)

Abstract

It is very important to decide which theory is most advantageous among the three thories in the diurnal variation of the earth magnetic field. The author investigates the motion of electron in the ionosphere and obtains another drift current and conductivity to be unsymmetry tensor with nine components, from which those given by Pederson, parallel (σο) or perpendicular (σ_??_) to the magnetic field is deduced for a special case. Owing to the differences of the collisional and gyromagnetic frequencies, this newly introduced current and conductivity (σ_??_) due to positive and negative ions or electron, though having different signs, are not nil in all up to the height where the collisional frequencies are far lower compared with gyromagnetic, Considering the typical layer, we expand the conductivities in power series of sin θ or cos θ approximately and calculate the magnetic field produced by the atmospheric semi and diurnal oscillations.
The theoretical field from σ_??_ shows too small amplitude ratio in diurnal harmonic and the phase lag as of old, while that from σ_??_, satisfactory accordance with the Chapman's analysis in amplitude ratio, but the phase difference is the great obstacle as it was.
Drift current will be thought to be impossible to give an explanation, so far as this study is concerned, to the observed amplitude ratio and phase angles which are similar in all harmonics, … introduction of the new current is still worse.