Digital ionosonde observations of Pc3–4 pulsations across the plasmapause
Pc3–4 magnetic pulsations have been observed at Halley, Antarctica (L = 4.2), simultaneously with oscillations in the phase of F-region echoes received using a digital ionosonde.
One event, lasting more than 6 hours in the afternoon of 15 December 1982, shows a crossing of the plasmapause as Halley moved into the bulge region of the plasmasphere. On the ionosonde it is marked by a change in frequency of the Pc3–4 oscillations and a short lived or sharply bounded charged particle precipitation event. On the magnetometer it can be deduced from the changes in ellipticity of pulsations occurring simultaneously at three separate frequencies. The amplitude of the ionosonde phase pulsations is shown to peak when the field line with that natural resonant frequency passes through the observation site.
Cross spectral analysis techniques have been used on this event to investigate the relationships between the magnetic field components and ionospheric echo parameters, and the physical processes linking the two. The phase difference between the magnetometer and ionosonde pulsations is highly variable. Detailed analysis supports a combination of direct compressional action by the hydromagnetic wave and vertical motion induced by an E × B drift.