Course: Topics in Discharge Phenomena (Fall 2003) Resonances in the Earth-Ionosphere Cavity by A.P. Nickolaenko & M. Hayakawa (Kluwer 2002)

Introduction theme: e.m. resonance phenomena in the Earth-Ionosphere cavity tool for probing global thunderstorm activity and properties of lower ionosphere focus primarily at Schumann resonance (SR; predicted by W.O. Schumann in 1952) at 8, 14, 20 Hz Fundamental parameters of the Earth-Ionosphere cavity conducting earth and ionosphere lower 30 km of atmosphere as dielectric sustaining e.m. waves at very low frequency (VLF) band : 3 – 30 KHz extremely low frequency (ELF) band : 3 – 30 Hz, with wavelength of ~40,000 km (4 Mm)

Historical N. Tesla (1893): first attempt to artificially excite e.m. waves in the E-I cavity A.P. Popov (1895): first detection of natural e.m. radiation from thunderstorms G. Marconi (1901): used spark transmitters to send and receive radio signals across the Atlantic E.O. Schumann (1952): predicted e.m. waves from thunderstorm activity could excite global e.m. resonance, aka Schumann Resonance (SR) Balser & Wagner (1960): first confirmation of the SR SR researches were aimed at military application, e.g. in submarine communication; 1990s: interests renewed after the discovery of sprites and other TLEs; TLEs are sources of Q-burst band below 50-60 Hz and slow tails above 300 Hz (reading: Boccippio et al., Sprites, ELF transients and Positive Ground Strokes. Science, 269, 1088-1091,1995; Cummer, JASTP 2003) Three major thunderstorm regions: equatorial Africa, America and Southeast Asia

Global lightning distribution (Sep-Nov, 1999)

Resonances in the E-I cavity by simple geometrical argument Longitudinal resonance (SR); where the radius of Earth a is 6400 km Transverse resonance; where the height of the E-I cavity h is taken as 75 km The transverse resonance frequencies is two orders of magnitude higher than those of the SR. No mixing is possible.

Characteristics of lower ionosphere Electron gyrofrequency (cyclotron freq): Plasma frequency: Conductivity: Siemens (Sm):

Special foci of this book Practical information on site selection, layout, antenna and receiver characteristics, and system calibration Detailed formalism on Schumann resonance; for both uniform isotropic and non-uniform anisotropic E-I cavity Effective/engineering models for lightning discharges Parameterization of global thunderstorm activity and its usage in interpreting the seasonal and interannual modifications in the SR recordings Statistical models of natural radio signals in the frequency and time domains Techniques of signal processes; how to extract particular geophysical information from SR recordings