Equatorial F2-layer peak height and correlation with vertical ion drift and M(3000)F2 Original Research Article

Ionosonde data recorded at Korhogo, Côte-dʹIvoire (Latitude +9.3; Longitude −5.4, Dip −0.67) during a year of low solar activity (1995) were used to investigate ways of improving the representation of equatorial F2 peak height (hmF2) in the International Reference Ionosphere (IRI). For this purpose we have studied the correlation between hmF2 and the equatorial F region vertical drift as given by the model of Scherliess and Fejer (1999). The positive correlation found during nighttime could be helpful in representing the post-sunset peak of hmF2 that is currently not represented by IRI. We have also investigated the reliability of the CCIR model for the propagation factor M(3000)F2 model since the IRI hmF2 model is based on the strong anti-correlation between hmF2 and M(3000)F2. Overall the CCIR model represents the diurnal variation of M(3000)F2 quite well but does not represent small-scale features. With the M(3000)F2 values deduced from the Korhogo ionograms as input, the IRI hmF2 model provides an excellent representation of the observed diurnal structure including the post-sunset peak.