Doppler observations of associated ionospheric and magnetic fluctuations

Abstract

Observations of ionospheric motions associated with magnetic micropulsations were conducted during a three-year period.Current theoretical models of the interaction indicate that observable Doppler shifts of high-frequency radio waves coherently reflected from the ionosphere should accompany all reasonably large geomagnetic disturbances, and vice versa, but this is not observed. Detailed studies of particular classes of events were therefore undertaken, involving spectral analyses, cross correlations, diurnal and seasonal occurrence statistics, and studies of associations with various types of ionospheric and magnetic records.Certain classes of magnetic pulsation events are found to be directly associated with F-region motions. Of the many possible mechanisms which may be responsible for these associations, two stand out as prime candidates: (i) hydromagnetic waves and (ii) neutral-gas waves modulating ionospheric electrojets. At mid-latitudes during quiet-sun years, the direct effects of precipitation of charged particles appear to be of much less importance.