Diurnal variations of the zonal structure of the ionospheric F-region at low latitudes in February 1980

The appearance and development of zones of high and low electron density in the F-region in the course of a day in February 1980 were investigated on the basis of vertical-sounding data at low latitudes. Certain zones over African, Indian, and southern Japanese territories are identified where f0F2 and hmF2 experience dissimilar variations. In the course of a day, four periods six hours long with stable variations of F2-layer parameters are identified in these zones.