ELF Attenuation Rates and Phase Velocities Observed From Slow-Tail Components of Atmospherics


  • W. L. Taylor,

  • K. Sao


Slow-tail portions of atmospherics were recorded simultaneously in Japan and the United States from sources located in the Pacific Ocean area. The amplitude and phase spectra of forty pairs of selected atmospherics were computed, and propagation parameters for the zero-order wave-guide mode were calculated for nighttime conditions only. Attenuation rates for W-E propagation extended from about 0.5 db/Mm at 20 Hz to 2.0 db/Mm at 300 Hz and for E-W propagation from 0.8 db/Mm at 20 Hz to about 2.8 db/Mm at 300 Hz. The phase velocities extended from about 0.7 and 0.8 the velocity of light for W-E and E-W propagation, respectively, at 20 Hz to about 0.93 the velocity of light for either direction at 300 Hz.