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| Titel |
Conjugate observations of a remarkable quasiperiodic event by the low-altitude DEMETER spacecraft and ground-based instruments |
| VerfasserIn |
Barbora Bezdekova, Frantisek Nemec, Jyrki Manninen, Michel Parrot, Ondrej Santolik, Mykhaylo Hayosh |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250123395
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| Publikation (Nr.) |
 EGU/EGU2016-2636.pdf |
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| Zusammenfassung |
| Quasiperiodic (QP) events are electromagnetic waves observed in the inner magnetosphere at
frequencies between about 0.5 and 4 kHz that exhibit a nearly periodic modulation of the
wave intensity. The modulation periods may range from tens of seconds up to minutes. We
present a detailed multipoint analysis of a remarkable QP event observed consecutively for
several hours on 26 February 2008. The event was detected by ground-based instruments of
Sodankyla Geophysical Observatory (Finland) and by the low-altitude DEMETER
spacecraft, both in the same and conjugate hemispheres. The time intervals when the event
was observed on board the satellite/on the ground provide us with an estimate of the
event dimensions. When the event is detected simultaneously by the satellite and on
the ground, its observed frequency-time structure is generally the same. However,
the ratio of detected intensities varies significantly as a function of the spacecraft
latitude. Moreover, there is a delay as large as about 10 s between the times when
individual QP elements are detected by the spacecraft/on the ground. This appears to be
related to the azimuthal separation of the instruments, and it is highly relevant to the
identification of a possible source mechanism. Finally, we find that the intensity of the QP
event is correlated with the amplitude of Alfvenic ULF pulsations measured on the
ground. |
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