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| Titel |
On the usefulness of E region electron temperatures and lower F region ion temperatures for the extraction of thermospheric parameters: a case study |
| VerfasserIn |
J.-P. St.-Maurice, C. Cussenot, W. Kofman |
| 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 ; 17, no. 9 ; Nr. 17, no. 9, S.1182-1198 |
| Datensatznummer |
250013811
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| Publikation (Nr.) |
 copernicus.org/angeo-17-1182-1999.pdf |
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| Zusammenfassung |
Using EISCAT data, we have studied the
behavior of the E region electron temperature and of the lower F
region ion temperature during a period that was particularly active
geomagnetically. We have found that the E region electron temperatures
responded quite predictably to the effective electric field. For this reason,
the E region electron temperature correlated well with the lower F
region ion temperature. However, there were several instances during the period
under study when the magnitude of the E region electron temperature
response was much larger than expected from the ion temperature observations at
higher altitudes. We discovered that these instances were related to very strong
neutral winds in the 110-175 km altitude region. In one instance that was
scrutinized in detail using E region ion drift measurement in conjunction
with the temperature observations, we uncovered that, as suspected, the wind was
moving in a direction closely matching that of the ions, strongly suggesting
that ion drag was at work. In this particular instance the wind reached a
magnitude of the order of 350 m/s at 115 km and of at least 750 m/s at 160 km
altitude. Curiously enough, there was no indication of strong upper F
region neutral winds at the time; this might have been because the event was
uncovered around noon, at a time when, in the F region, the E×B
drift was strongly westward but the pressure gradients strongly northward in the
F region. Our study indicates that both the lower F region ion
temperatures and the E region electron temperatures can be used to
extract useful geophysical parameters such as the neutral density (through a
determination of ion-neutral collision frequencies) and Joule heating rates
(through the direct connection that we have confirmed exists between
temperatures and the effective electric field).
Key words. Ionosphere (auroral ionosphere; ionosphere
atmosphere interactions; plasma temperature and density) |
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