Cosmic noise absorption at South Pole and Frobisher Bay: Initial results

概要

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A 30MHz riometer was installed at Frobisher Bay, Canada, in July 1985 to enable conjugate studies of cosmic noise absorption (CNA) phenomena to be performed in conjunction with observations from Amundsen-Scott South Pole station. The riometer data reveal a variety of temporal associations between disturbances appearing in opposite hemispheres which are generally consistent with observations at these sites reported previously. These include events with simultaneous onsets and similar time variations, closely similar events but with onset times and absorption maxima differing by several minutes, and absorption events appearing in one hemisphere only. For the present data set, however, fluxgate magnetometer data from both locations aid in interpreting the observed phenomena. In particular, absorption events and intense electrojet currents in the dusk sector were found to occur preferentially in one hemisphere (mainly at the South Pole during the period July-September examined here). Because the magnetometer can sense the presence of electrojets far from its immediate vicinity, these cases appear to be evidence of nonconjugate electron precipitation (perhaps occurring on open field lines) or of the severe distortion of the magnetic field line topology in this local time region. Absorption in the noon sector is characterized by long-period modulations in the Pc 5-6 range.
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