A theoretical analysis of the time dependent distribution of ionization in the low-latitude ionosphere is performed by using a realistic dynamic computer model of the equatorial F region, with special interest in the vertical motions of the electron density profile at the magnetic equator. The time dependence of the F2 peak height, at the magnetic equator, is governed primarily by the electromagnetic E¿B plasma drift velocity. It is shown that, for special time periods during sunset and evening hours, when the height of the F layer is above a threshold of 300 km, the apparent vertical displacement velocity of the F layer, inferred from ionosonde measurements, is the same as the vertical E¿B plasma drift velocity, as determined from incoherent backscatter radar measurements in the F region.