Cusps and Distortions in Ionospheric FI-layer observed over Kodaikanal

Abstract

A special study of cusps and distortions in F1-layertraces has been made from ionograms obtained at Kodaikanal during a period of about half a solar cycle. Two different types of disturbance have been noticed. The first one is stationary type occurring near the low frequency end of the F1-layer trace. It is suggested that these ridges found in the course of a disturbance are connected with the E2-layer. In the second type, the cusp appears to move along the virtual height curve and these are ascribed to traveling wave-type disturbance. It is also found that these disturbances are associated with the disappearance of equatorial E₈ on magnetically disturbed days, An explanation of the phenomenon is attempted in terms of internal gravity waves proposed by Hines (1960).