Diurnal behaviour of midlatitude F-region parameters in summer

Some aspects of the day-to-day variations in the diurnal behavior of F-region total electron content (TEC) and peak electron density (NmF2) at midlatitudes during summer months are studied using systematic and extensive series of TEC measurements made at two midlatitude stations (Auckland and Invercargill, New Zealand) and NmF2 data obtained at two ionosonde stations (Auckland and Christchurch, New Zealand). Hourly values of NmF2 and TEC at these stations are analyzed with respect to bite-out pattern for the local summer months of each year from 1965-66 to 1973-74, covering the last solar cycle. It is found that, on average, the structure of the bite-out exhibits a tendency for a more or less systematic variation with the phase of the solar cycle. The results suggest that global atmospheric neutral winds play a role in the day-to-day variation of the bite-out pattern in TEC and NmF2 at midlatitudes.