Dynamics of equatorial F region irregularities from spaced receiver scintillation observations

Spaced receiver observations of amplitude scintillations on a 244 MHz signa l, at an equatorial station, have been used to study random temporal change s associated with the scintillation-producing irregularities and the variab ility of their motion. The computed drift of the scintillation pattern show s the presence of velocity structures associated with equatorial bubbles in the early phase of their development. On magnetically quiet days, after 22 :00 LT, the estimated drifts fall into a pattern which is close to that of the ambient plasma drift. There is considerable decorrelation between the t wo signals until 22:00 LT. The power spectra of the most highly correlated scintillations recorded by spaced receivers indicate that the associated ir regularities are confined to a thin layer on the bottomside of the equatori al F region. This suggests that file convection pattern associated with bot tomside irregularities is stable due to the dominance of ion-neutral collis ions over ion inertia.