Response of equatorial and low latitude F-region to the great magnetic storm of 13 March 1989

The storm-time effects observed in the ionospheric F-region data of Kodaikanal. Manila and Chung-Li for the great storm of 13 March, 1989 are presented. The most significant features observed are a dramatic collapse in nighttime electron density at Kodaikanal and large daytime decreases at both Manila and Chung-Li. Sharp decreases of electron density following sudden commencement (SC) are also observed. The nighttime decrease at Kodaikanal can be explained partly in terms of increased loss rates arising due to lowering of alyer heights and increased neutral temperatures, while the daytime decreases at Manila and Chung-Li appear to be the result of intensified fountain. Effects observed immediately following the SC are interpreted in terms of magnetospheric electric fields penetrating to low latitudes