Observations of radio star scintillations and spread-F echoes over a solar cycle

摘要: Abstract Observations of the scintillations radio source Cassiopeia A were made at Cambridge on a frequency 38 Mc/s over period 1949–1961. The results are presented in form curves showing mean diurnal variation scintillation index for each month. variations with solar time, sidereal time and zenith angle derived discussed. Seasonal cycle also considered. Ionograms from Slough analysed to study occurrence spread-F echoes 1949–1960, compared observations scintillations. Special consideration is given cycle, which opposite two phenomena; effect greatest sunspot maximum, but occur more frequently minimum. It concluded that maximum ionospheric irregularities cause star must be mainly above level ionization F-region, therefore unobservable by ground-based sounders. For years near sun-spot day as well night. Possible explanations these daytime