Upward moving ionospheric irregularities over Kodaikanal

Abstract

The occurrence of upward moving kinks first found on ionograms at Thumba (Rastogi, 1970) has been confirmed to occur at another equatorial station, Kodaikanal. These kinks have been found in many records and they occur mostly during local summer months. The occurrence of the kink is shown to be closely associated with horizontal F-region drifts, occurrence of intermediate cusp between F₁ and F₂ layers, bite-out effects of ƒ₀F₂ and rise of h_PF₂, all being most pronounced around 10 hr. The upward movement of the kink is due to E ^→x B^→ drift, while its initiation is probably due to a sudden change in the electrostatic field of the equatorial electrojet. The study of the upward moving kink gives a direct measure of the height variation of the vertical upward drift of ionization over the magnetic equator.