HF Radar Observations of Pc3-5 Pulsations

Hitoshi MATSUOKA* (1), A. Sessai YUKIMATU (1), H. YAMAGISHI (1), N. SATO (1), and T. MUKAI (2)
(1) NIPR, Japan, * Now at NASDA, Japan
(2) ISAS, Japan

In spite of accumulated observations of ULF pulsations, there is no satisfactory explanation for the generation and transmission mechanisms of Pc 3 pulsations at very high latitudes. Therefore, we have studied the characteristics of high-latitude Pc 3 pulsations using data acquired in the ionosphere by the SuperDARN radars and in space by the GEOTAIL satellite. We have shown earlier that narrow-band Pc 3 pulsations are occasionally observed in Doppler velocity data by the HF radars, and that there is a clear peak in the Pc 3 power near the cusp latitudes. Furthermore, we have found that compressional magnetic field variations in the early morning magnetosheath include spectral peaks identical to the Pc 3 pulsations detected by the radars. The results suggest that the driving source is located outside the magnetosphere, and that part of the energy of the driving source is transmitted to the ionosphere along cusp/LLBL magnetic field lines. In order to extend these results, coordinated SuperDARN and GEOTAIL measurements were carried out in January-March, 2000. We will discuss these pulsation events in detail at the meeting.

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