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| Titel |
On the coupling between unstable magnetospheric particle populations and resonant high m ULF wave signatures in the ionosphere |
| VerfasserIn |
L. J. Baddeley, T. K. Yeoman, D. M. Wright, K. J. Trattner, B. J. Kellet |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 23, no. 2 ; Nr. 23, no. 2 (2005-02-28), S.567-577 |
| Datensatznummer |
250015161
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| Publikation (Nr.) |
 copernicus.org/angeo-23-567-2005.pdf |
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| Zusammenfassung |
| Many theories state that Ultra Low Frequency (ULF) waves with a high
azimuthal wave number (m) have their energy source in wave-particle
interactions, yet this assumption has been rarely tested numerically and
thus many questions still remain as to the waves' exact generation mechanism.
For the first time, this paper investigates the cause and effect
relationship between the driving magnetospheric particle populations and the
ULF wave signatures as observed in the conjugate ionosphere by
quantitatively examining the energy exchange that occurs. Firstly, a Monte
Carlo method is used to demonstrate statistically that the particle
populations observed during conjugate ionospheric high m wave events have
more free energy available than populations extracted at random. Secondly,
this paper quantifies the energy transferred on a case study basis, for two
classes of high m waves, by examining magnetospheric Ion Distribution
Functions, (IDFs) and directly comparing these with the calculated wave
energy dissipated into the conjugate ionosphere. Estimates of the wave
energy at the source and the sink are in excellent agreement, with both
being of the order of 1010J for a typical high m wave. Ten times more
energy (1011J) is transferred from the magnetospheric particle
population and dissipated in the ionosphere when considering a subset of
high m waves known as giant pulsations (Pgs). Previous work has demonstrated
that 1010J is frequently available from non - Maxwellian IDFs at L=6, whereas 1011J is not.
The combination of these studies thus provides
an explanation for both the rarity of Pgs and the ubiquity of other high m
waves in this region. |
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