Resonances in the Earth-Ionosphere Cavityby A.P. Nickolaenko & M. Hayakawa

(Kluwer 2002)

Course: Topics in Discharge Phenomena(Fall 2003)

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)

Introduction

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

Historical

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.

kma 000402 ,

Hznnacfn 572

.

HzpphcFp 31022

Characteristics of lower ionosphere

Electron gyrofrequency (cyclotron freq):

Plasma frequency:

Conductivity:

Siemens (Sm):

mne

p2

gattenuatintraveling pp ;

effeff

effm

ne

12

;

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