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

2. 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)

3. 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 Hz and slow tails above 300 Hz (reading: Boccippio et al., Sprites, ELF transients and Positive Ground Strokes. Science, 269, ,1995; Cummer, JASTP 2003)
Three major thunderstorm regions: equatorial Africa, America and Southeast Asia

4. Global lightning distribution (Sep-Nov, 1999)

5. 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.

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

7. 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