The principle of SR measurement: the magnetic and electric components

The Schumann resonance manifests itself as a standing electromagnetic wave in the Earth-ionosphere cavity. In measurement, three field components are typically recorded: two horizontal magnetic components (north-south and east-west) using induction coils and the vertical electric component using a ball antenna Tatsis 2024.

The signal is exceptionally weak. Typical amplitudes of magnetic induction are on the order of tenths to a few picotesla (pT) per mode, while the vertical electric field reaches on the order of hundreds of nV/m (more precisely, the spectral density is given in nV/m/√Hz) Tatsis 2024. These levels are far below the values of ordinary anthropogenic interference, which places extreme demands on the sensitivity of the instruments and on the choice of location.

Two-component recording of the magnetic field makes it possible to determine the direction (azimuth) to the lightning source, while the vertical electric field is advantageous for analyzing frequency shifts associated with global storm activity. The combination of components is the basis for determining the location of sources and for studying diurnal and seasonal variations.