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| Titel |
Comparison of the measured and modeled electron densities, and electron and ion temperatures in the low-latitude ionosphere during 19-21 March 1988 |
| VerfasserIn |
A. V. Pavlov, S. Fukao, S. Kawamura |
| 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 ; 22, no. 8 ; Nr. 22, no. 8 (2004-09-07), S.2747-2763 |
| Datensatznummer |
250014962
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| Publikation (Nr.) |
 copernicus.org/angeo-22-2747-2004.pdf |
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| Zusammenfassung |
| We have presented a comparison between the modeled NmF2 and
hmF2, and NmF2 and hmF2 which were observed at the equatorial anomaly crest
and close to the geomagnetic equator simultaneously by the Akita, Kokubunji,
Yamagawa, Okinawa, Chung-Li, Manila, Vanimo, and Darwin ionospheric sounders
and by the middle and upper atmosphere (MU) radar at Shigaraki
(34.85°N, 136.10°E, Japan) during the 19-21 March 1988
geomagnetically quiet time period at moderate solar activity near
approximately the same geomagnetic meridian of 201°. A comparison
between the electron, Te, and ion, Ti, temperatures measured by
the MU radar and those produced by the model of the ionosphere and
plasmasphere is presented for 19-21 March 1988. It is shown that there is
a large disagreement between the measured and modeled hmF2 from about
07:00 UT to about 11:00 UT if the equatorial ExB drift given by
Scherliess and Fejer (1999) is used. The required equatorial upward ExB drift is weaker from 03:14 UT to 11:14 UT than that given by Scherliess
and Fejer (1999) for the studied time period. The required modification of
the ExB drift weakens the effect of the fountain in NmF2 bringing the
modeled and measured hmF2 and NmF2, into reasonable agreement. The depth of
the equatorial NmF2 trough in the calculated NmF2 is approximately
consistent with the measured depth if the modified equatorial ExB drift is used. It has been found that the north-south asymmetries in the
observed NmF2 and hmF2 about the geomagnetic equator are mainly caused by
the asymmetry in the neutral wind about the geomagnetic equator. In the
Northern Hemisphere, the meridional neutral wind taken from the HWW90 wind
model and the NRLMSISE-00 atomic oxygen density are corrected so that the
model results agree with the ionospheric sounders and MU radar observations.
A theory of the primary mechanisms causing the latitude dependence of the
morning and evening peaks in Te is developed. The latitude dependence
of the magnitudes of these peaks in Te is interpreted in terms of
the corresponding dependence of the electron density. The relative role of
the ExB drift and the plasma drift caused by the neutral wind in the
formation and the dependence of the magnitudes of the morning and
evening electron temperature peaks on the geomagnetic latitude is studied. |
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