Magnetic storm phenomena at low latitudes are discussed based on the ion composition (0+, H+, He+) and electron and ion temperature measurements from the OGO-4 and the ISIS-2 satellites.For the moderately severe storms considered, the effects of changes in the neutral composition and in the neutral and plasma temperatures are discussed and it is shown that these changes would not produce the observed 0+ increase during storms at low latitudes. It is suggested that the observed increase in 0+ in the topside region is a manifestation of the vertical lifting of ionization of the F-layer. The argument in favour of the vertical lifting is further substantiated by the observed changes in the F-region critical frequency and the height parameters.