Some additional features of radar returns from the equatorial electrojet

This paper reports the results of recent VHF experiments designed to investigate the fine structure of the equatorial electrojet. The results of two separate experiments are reported. The first result shows that during the course of the experiments, except for midday periods, the vertical structure of the echoing region as observed by VHF radar techniques exhibits a pronounced bifurcation. The second experiment demonstrates the existence of movements of irregularities embedded in the electrojet region. The velocity of these movements inferred from the data are seen to be substantially below the velocity ascribed to the plane wave irregularities produced by a two-stream plasma instability which account for the major part of the reflected VHF radar signal. The observed motions may be associated with another type of plasma instability or may possibly be horizontal drifts of large irregularities in the region.