Pearl structures of Pc1 geomagnetic pulsations observed at multipoint ground stations at Russia, Japan and Canada
Abstract
Pc1 geomagnetic pulsations propagate from high to low latitudes through the ionospheric wave duct. A few papers had shown longitudinal propagation of Pc1 pulsations [e.g., Kawamura et al. 1981; Sakaguchi et al.2012]. Despite these previous researches, diurnal variations of longitudinally-distributed Pc1 pulsations and the pearl structures at different stations have not been investigated yet. In order to understand generation and propagation processes of Pc1 pulsations in the magnetosphere and the ionosphere, it is necessary to investigate spatial distribution of Pc1 pulsations using magnetometers at longitudinally and latitudinally separated ground stations. We have investigated spatial distributions of the Pc1 pulsations observed by induction magnetometers at three ground stations at Moshiri (MOS) in Japan, Magadan (MGD) in far-eastern Russia and Athabasca (ATH) in central Canada from January 2009 to December 2011. Simultaneous Pc1 events observed at MGD and ATH occurred in the morning and afternoon sectors. This result is consistent with the global distribution of EMIC waves observed in space [Min et al. 2012]. The simultaneous Pc1 events with high coherence (> 0.5) observed at ATH and MGD concentrates in the afternoon to pre-midnight sector. The Pc1 frequencies of the simultaneous Pc1 events at ATH and MGD in the afternoon to pre-midnight sector were higher than those in the post-midnight to morning sector. Most of the simultaneous Pc1 events with high coherence observed at ATH and MGD have different pearl structures. This result indicates that the pearl structures should be not caused in the magnetosphere, and rather made during the propagation in the ionospheric duct. Simultaneous Pc1 events observed at MGD and MOS at subauroral and middle latitudes, respectively, were most frequently observed at night suggesting that propagation in the ionospheric duct suffers less attenuation at night. In the presentation we discuss these results in combination with the EMIC wave distribution in the magnetosphere and their propagation to the ionosphere and in the ionospheric duct.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFMSM43A2269J
- Keywords:
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- 2431 IONOSPHERE Ionosphere/magnetosphere interactions;
- 2730 MAGNETOSPHERIC PHYSICS Magnetosphere: inner;
- 7867 SPACE PLASMA PHYSICS Wave/particle interactions;
- 2774 MAGNETOSPHERIC PHYSICS Radiation belts