The diurnal development of the anomalous equatorial belt in the F2 region of the ionosphere

Abstract

The latitudinal variation in the critical frequency of the F2 layer was studied for each hour of the day during the equinoctial months of a year at sunspot minimum. The middle latitude maxima first develop at low latitudes and shift poleward with the progress of the day, the course being reversed in the evening hours. The double maxima in the diurnal variation of ƒ0F2 are less separated with increasing latitude and finally converge to a single maximum at a dip of about 25°. These two anomalies in ƒ0F2 are suggested as being due to the vertical drift of ionization, together with its motion towards the poles in the morning and towards the equator in the afternoon. Other anomalies of F2 can also be explained by a meridional transport of ionization.