Auroral VLF Emissions in Antarctica

概要

論文の詳細を見る
Recent topics of VLF observations at Syowa Station, Antarctica, are summarized. In the frequency-time spectra of quasi-periodic VLF emissions, regular modulation is often found accompanying Pc 4 and Pc 5 pulsations, while complex patterns of modulation are observed usually in association with Pc 2 or Pc 3 pulsations, whose period is shorter than 30∿40 seconds. A certain kind of ELF noise band with a center frequency of about 300 Hz is sometimes observed during auroral hiss events. The noise band is nearly monochromatic and the duration is about ten seconds. The spectral characteristics of the noise are very similar to those of a ELF noise associated with low-energy auroral electron precipitation, found by the Injun 5 observation. During the recovery phase of substorm, chorus emission of a special type is observed in the early morning. The spectral structure of this chorus is considerably different from that of the daytime chorus. The emission consists of groups of risers of about 0.2 seconds in duration, and the time interval of these groups is of the order of 10 seconds. A typical event comprises short sequences of riser groups overlapping in time in the frequency range of 0.5∿2kHz. Relationship between this chorus and pulsating auroras is discussed on the basis of the coordinated VLF and auroral TV experiments.
国立極地研究所の論文