Application of McCormick-Cohen Model for Computing ELF/VLF Atmospherics

Abstract

. In a recent paper by McCormick and Cohen (2021), the new vertical profiles were discussed of electron density in the D/E region of ionosphere that accounts for the observations of VLF atmospherics (sferics). In the present paper, we use a typical profile from this paper and apply the classical profile of electron effective collision frequency for obtaining the conductivity of middle atmosphere. This air conductivity profile is compared then with those matching the Schumann resonance observations. By using this novel conductivity model, we compute the propagation parameters of ELF-VLF modes in the Earth–ionosphere cavity with the help of full-wave solution. An emphasis is made on the comparison of Schumann resonance spectra found for the existing and the novel profiles. The multi-mode full-wave solutions allowed us to compute the wide-band complex spectra of vertical electric and horizontal magnetic field components by using the classical modal expansions. Finally, the pulsed waveforms were calculated using the Fourier transform of complex ELF/VLF spectra, which belong to typical slow tail atmospherics (sferics). The conclusion is made that the profile by McCormick and Cohen underestimates the radio wave attenuation only at ELF, so that relevant data predicts somewhat higher peak frequencies and Q-factors of Schumann resonance.