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| Titel |
Poker Flat Incoherent Scatter Radar observations of anomalous electron heating in the E region |
| VerfasserIn |
R. A. Makarevich, A. V. Koustov, M. J. Nicolls |
| 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 ; 31, no. 7 ; Nr. 31, no. 7 (2013-07-03), S.1163-1176 |
| Datensatznummer |
250019060
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| Publikation (Nr.) |
 copernicus.org/angeo-31-1163-2013.pdf |
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| Zusammenfassung |
| A comprehensive 2-year dataset collected with the Poker Flat Incoherent
Scatter Radar (PFISR) located near Fairbanks, Alaska (MLAT = 65.4° N)
is employed to identify and analyse 22 events of anomalous electron heating
(AEH) in the auroral E region. The overall AEH occurrence probability is
conservatively estimated to be 0.3% from nearly-continuous observations of
the E region by PFISR, although it increases to 0.7–0.9% in the dawn
and dusk sectors where all AEH events were observed. The AEH occurrence
variation with MLT is broadly consistent with those of events with high
convection velocity (>1000 m s−1) or electron temperature (> 800 K), except
for much smaller AEH probability and absence of AEH events near magnetic
midnight. This suggests that high convection electric field by itself is
necessary but not sufficient for measurable electron heating by two-stream
plasma waves. The multi-point observations are utilised to investigate the
fundamental dependence of the electron temperature on the convection electric
field, focusing on the previously-proposed saturation effects at extreme
electric fields. The AEH dataset was found to exhibit considerable scatter
and, on average, similar rate of the electron temperature increase with the
electric field up to 100 mV m−1 as compared with previous studies. At higher
(highest) electric fields, the electron temperatures are below the linear
trend on average (within uncertainty). By employing a simple fluid model of
AEH, it is demonstrated that some of this deviation from the linear trend may
be due to a stronger vibrational cooling at very large temperatures and
electric fields. |
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