A Theory of Geomagnetic Micropulsations II

Abstract

The amplitude spectrum of micropulsation signal at the surface of the earth is essentially determined by the resonances of the transmission path. On the other hand the power spectral density depends both on the squared amplitude of transmission and the occurrence or persistence probability. This latter probability is a function of the sensitivity of the overall transmission on the variation of the path length in the outer magnetosphere.A crude analysis based on this sensitivity yields spectral peaks at time periods of approximately 2.5, 6, 11 and 20 seconds with a slope of 6 db/octave at long time periods only.

Substorm aspects of magnetic pulsations

“…The knowledge of both amplitude * Note that the power spectral density above the ionosphere can be obtained by multiplying the power spectral density observed on the ground by the squared transmission coefficients only if the source is white noise and if the transmission path has no statistical variations. If this is not the case, another approach must be used (Sen, 1968a). and polarization in the magnetosphere is fundamental with respect to the generation mechanisms; therefore, propagation effects must be well understood.…”