2004 年 124 巻 12 号 p. 1225-1231
The extremely low frequency propagation associated with Schumann resonance phenomena are calculated numerically by the frequency-domain finite difference method, and distribution of source lightnings is identified by solving an inverse problem using the computed spectra as a set of basis functions. The finite difference equations are formulated in terms of discretized magnetic fields in the Cartesian coordinates adopting a cylindrical shell cavity for simplicity. The most reliable electron and neutral density models in the atmosphere and the ionosphere can be used to take into consideration propagation losses. The inverse problem already developed is applied to the measured data to reconstruct lightning activity distribution as a function of distance from the observation point. The reconstructed data successfully show the lightning active season, time, and distance, which are reasonable in comparison with the earlier reports.