Q FACTORS OF THE SCHUMANN RESONANCES AND SOLAR ACTIVITY

Abstract

The vertical components of natural electromagnetic noises of ELF were observed by using a ball antenna, and the power spectra of the earth-ionosphere cavity resonances were produced by using a sonagraph. The peak frequencies and the band widths of 3 db down from the peak were read from over 2000 spectra thus produced in the period from February 1967 to January 1968, and Q factors of the resonances were estimated to be 3.30, 4.52, and 4.92 for the fundamental, second, and third modes respectively. Comparing these values with the previous experimental and theoretical values it is concluded that the greater part of resonant energy is dissipated in the region of ionic conductivity below 56 km. An inverse relation between Q factors and solar activity was found and it is concluded from this that the effective height of the upper boundary of the cavity decreases as the sun becomes active. It is suggested that the sun may have some effect in modifying the conductivity profile below 56 km of the atmosphere.