Seismo-electromagnetic phenomenon in terms of 3D vector problem of subionospheric radio wave propagation across the solar terminator

This paper presents a further development of mathematical model, an asymptotic theory and an appropriate numerical algorithm to study the vector VLF point source field propagation problem within the non-uniform Earth–ionosphere waveguide. It is the sequential development of our previous article [Soloviev, O.V., Hayakawa, M., Ivanov, V.I., Molchanov, O.A., 2004. Seismo-electromagnetic phenomenon in the atmosphere in terms of 3D subionospheric radio wave propagation problem. Phys. Chem. Earth 29, 639–647. doi:10.1016/j.pce.2003.10.002]. We have taken into account 3D local anisotropic ionosphere inhomogeneity over the ground of the solar terminator transition. The local ionosphere inhomogeneity, whose centre is situated above the model earthquake, is simulated by a bell-shaped tensor impedance perturbation of the ionospheric waveguide wall. The various propagation paths, which cut across the terminator line at different angles, have been investigated. Numerical results show that the emergence of the local ionosphere inhomogeneity on the radio wave propagation across the solar terminator path deforms the curves of field amplitude and phase diurnal variations in accord with the experimental observational data.