IONOSPHERIC INSTABILITIES AND FINE-STRUCTURE

Observations of irregularities in the equatorial and auroral electrojets are reviewed and are related to the theoretical work on current-driven plasma instabilities of the electrojets. The relevant instabilities appear to have been correctly identified and some progress on their non-linear development has been made. Observations of equatorial F-region irregularities are reviewed and the present state of the theory of plasma instabilities leading to the irregularities is briefly described. A very simple model illustrating how these irregularities could cause scintillation of SHF signals from satellites is provided but the literature on this subject is not reviewed. F-region irregularities at moderate and high latitudes are briefly discussed. Man-made ionospheric irregularities that result from powerful HF transmissions from the ground are mentioned together with possible mechanisms that could give rise to them. © 1979.