Schumann Resonances in Magnetic-Field Components

Research output: Contribution to journalArticle

Abstract

The Institut fur Geophysik Gottingen has facilities to record the time varying magnetic components H and D at extremely low frequencies (ELF) (0.1-20 Hz) continuously over several days, with a sampling rate of 100 Hz. The lower ELF-range is characterized by anthropogenic noise and the first two Schumann resonance modes of the Earth-ionosphere cavity. The local observations near Gottingen are distributed by thunderstorms during the summer that contribute a small part of the energy to the global thunderstorm activity. Transient natural signals with amplitudes of about 10 pT are superimposed on a continuous noise level of about 1 pT; both exhibit the Schumann resonance periodicities. The signals show a tendency to repeat after about 2 s which may suggest excitation by whistler-trains. The Schumann resonances are investigated by an analysis of the autocovariance matrix yielding a robust estimation of the amplitude, damping and frequency. All these parameters show a characteristic directional dependence and variability during the day. The amplitudes represent the excitation with different source locations of thunderstorm activity around the world, generating a dipole field within the resonator, while the damping and centre-frequency are related to solar activity coupling to the lower ionosphere.
Original languageEnglish
Pages (from-to)479-484
Number of pages6
JournalJournal of Atmospheric and Terrestrial Physics
Volume57
Issue number5
Publication statusPublished - 1995

Keywords

  • Ionosphere

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