DAY -TO- DAY - VARIABILITY IN SOME IONOSPHERIC PARAMETERS IN THE QUIET EQUATORIAL IONOSPHERE (CASE STUDY: f«F2 )

The F2 region of the Ionosphere is a complex one. There are large irregular changes of foF2 from day - to - day. This paper discusses the diurnal and seasonal variations of f0F2. While the diurnal variation of foF2 has a maximum value at a time far from mid-day, the seasonal variation curve has two maximum points in the months of March and November respectively, with a minimum in July. Thus, indicating that the seasonal variation of foF2 is a semi - annual one. It was also shown that for short time variations, the day-to-day variability in f0F2 is neither due to season nor relative sunspot number, Rz. The test of significance between the standard errors of foF2 before and after correction for season and Rz show no significant difference at 95% level of significance. The Ionosphere consists of a number of ionized regions above the earth's surface at a height of 60km to 100km containing ions which play an important role in the propagation of radio waves. It is made up of three layers namely; the D, E and F regions. The region in which this study is based is the F region- ionized region above E region which is further divided into fi and F2 layer in day- time. It is the critical frequency of Fj region that is used for this study. The predominant ions are No + and O + 2 in the F region produced by electromagnetic radiation. In