Model Measurements of Electromagnetic Variations near a Coastline for Localized Source Fields

抄録

The response of a sea-land interface to the induction fields of localized current systems in the ionosphere, represented by vertical and horizontal magnetic dipoles, is studied by means of a scaled model. Results giving the amplitudes of the vertical to horizontal magnetic field ratio (H_z/H_y) and the apparent resistivity (ρ_a) along a profile normal to the coast are presented for offshore, onshore and overhead locations of the dipoles. The model measurements for these sources indicate that the “coast effect” is more evident for points of observation over the sea than for points of observation over the land. The influence of an upwelling of a highly conducting zone in the substratum is also discussed.