Plasma Acoustic Propagation in the Ionosphere

Abstract

WE present here a discussion of how a new implication of the plasma acoustic theory¹ is related to some optical observations of auroras. We also discuss some experimental observations of magnetic and radio events at Saskatoon (magnetic latitude 60°). Since the idea of instabilities in the equatorial electrojet was extended to the case of the auroral electrojet¹, many auroral radio studies^2–5 have turned in this direction. Peak occurrence of echoes at a height of 100–120 km and speeds of 350–360 m/s have been obtained in some of the investigations³, and from others⁴ a peak echo occurrence at 110 km and average speeds of 310 m/s are suggested. In the latter, morning echoes could not have been due to plasma acoustic propagation, and in the others³ a “threshold effect” was observed in relation to magnetic events. This simply means that echoes appeared only when the intensity of the electrojet and hence the magnetic field exceeded a minimum value. Our interest in the present study is directed towards examination of a few experimental results of optical, magnetic and radio studies (made at Saskatoon) in relation to plasma acoustic propagation in the ionosphere.