Schumann resonances and electrical conductivity of the atmosphere and lower ionosphere—II. Evaluation of conductivity profiles from experimental Schumann resonance data

Abstract

Since resonance frequencies and Q of the Earth-ionosphere cavity in the 3–30 Hz ELF range depend upon the electrical conductivity of the space between ground level and 100 km altitude, it is possible to obtain a worldwide average of the atmosphere-lower ionosphere conductivity profile from an analysis of Schumann resonance noise (3–30 Hz) generated by global thunderstorm activity. An iterative procedure is described which involves use of the ELF data for locating the major noise sources (thunderstorm regions) and for determination of the vertical conductivity profile. Resonance frequencies are used to obtain profiles for the 40–100 km altitude range on four different days characterized by different solar and cosmic ray activity. The “ninety per cent widths” (related to cavity Q) of the ELF spectral peaks are then used to obtain an average value of the conductivity for the 0–45 km space and to modify the conductivity profile in the 60–75 km region. Results are compared with other published data on lower atmosphere and lower ionosphere conductivity.