On the occurrence of VHF and UHF scintillations and the zonal movements of irregularities during the low solar activity period of 1983-84

Scintillation data were recorded simultaneously using the Sirio satellite signal at 136 MHz and the Fleetsat signal at 244 MHz from September 1983 to August 1984 during the declining phase of the solar cycle. The data are analyzed to identify 143 patches of scintillations with durations and structures that are similar in both data sets. It is shown that the nocturnal variation in the occurrence of scintillations is maximum around 2100 hrs LT. The percentage of scintillation occurrences is highest during equinoxes. No significant scintillations are observed during the summer months. The computed velocities and patch durations are used to calculate the sizes of irregularities in the east-west direction.