抄録
The perturbation of alternating geomagnetic fields by a three-dimensional conductivity model is studied by a numerical technique. The model is a nonsymmetric island structure embedded in a layered half-space. Linearly polarized source fields of two different directions as well as a circularly polarized source field are studied. Three source field frequencies are considered. The results are presented as amplitude contours of the various field components over the surface plane. It is found that the perturbations in the fields are greater for shorter period. Also, the various maxima and minima in the amplitude contours associated with the island structure are dependent on the orientation of the source field. The results for the different polarization fields are compared, and the amplitude contours for the circularly polarized source field vary considerably from the linearly polarized cases.
