The effects of field-aligned ionospheric irregularities on satellite scintillations

Abstract

Observations of scintillations of radio signals from the satellites BEB and BEC made at Adelaide have been analysed to obtain information about the ionospheric irregularities which cause the scintillations. Observations of the radio diffraction pattern over the ground, made with three spaced receivers, indicate ionospheric irregularities aligned with their longer dimension along the Earth's magnetic field, and with axial ratios in the range 2–20. Observations of increases of scintillation depth when the direction of the radio ray is close to that of the magnetic field show effects in qualitative agreement with theory, but much larger in magnitude than would be expected on the basis of the above values of axial ratio. It is suggested that this result may indicate the presence of a new type of weakly ionized irregularities with very large values of axial ratio. However, further theoretical development appears to be necessary before a completely satisfactory model of such irregularities, consistent with all the observations, can be given.