Tóm tắt
A newly developed sensitive phase interferometer, based on a North–South and East–West antenna system, situated at London, Ontario, was used to record fast angle-of-arrival variations of the satellites ISIS-1 and ISIS-2 beacon transmissions at 136.410 MHz.The relative phase and corresponding amplitude scintillations indicate the presence of two distinct types of ionospheric irregularities which were classified as A-type and B-type. A-type predominantly occurred in a time interval centered on local midnight, and the major disturbance areas were south of the station. A number of them showed a near-field effect, which indicated the presence of F region field-aligned irregularities with large axial ratios.The B-type events, associated in publications with the sporadic E region, occurred at high elevation angles northwest and northeast of the station. Tentative results indicate that these events, predominantly recorded during daytime, are due to ionospheric irregularities occurring at altitudes considerably higher than those of the sporadic E region.
