On the occurrence and vertical movement of kink at Kodaikanal

Abstract

The occurrence of ionospheric irregularities observed as sharp discontinuities (kinks) on the ionograms and moving upward with time at Kodaikanal have been studied for a period covering high, medium, and low solar activity conditions. These kinks are most common during the summer season and during the morning (0900 LT) and the evening (1500 LT). The vertical velocities of these irregularities obtained by true height analysis of the ionograms lie in the range 10-40 m/s. The velocity shows a minimum around noon with no significant solar cycle dependence. One of the possible causes for the generation of these irregularities is suggested to be the accumulation of metallic ions over the equator by equatorward neutral winds or gravity waves, and their uplift is suggested to be due to the E × B drift.