ULF Wave Characteristics in the Auroral Zone through the Plasmapause

Abstract

Geomagnetic pulsations in the auroral zone through the plasma-pause were examined on the basis of IMS observation data obtained in Canada. It was shown that the geomagnetic pulsations in the daytime are reasonably accounted for in terms of HM waves propagating from outside, and that the pulsations in thedawn sector, on the other hand, are likely due to the fluctuations in the ionospheric electric currents related to the pulsating auroral precipitations. It was also shown that the wave characteristics of Pc 1 pulsations in the dusk sector are consistent with the confinement of their initial source region in a small extent, spreading through the upper ionosohenc duct.