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| Titel |
Maps of foF2, hmF2, and plasma frequency above F2-layer peak in the night-time low-latitude ionosphere derived from Intercosmos-19 satellite topside sounding data |
| VerfasserIn |
G. F. Deminova |
| 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 ; 25, no. 8 ; Nr. 25, no. 8 (2007-08-29), S.1827-1835 |
| Datensatznummer |
250015899
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| Publikation (Nr.) |
 copernicus.org/angeo-25-1827-2007.pdf |
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| Zusammenfassung |
Maps of foF2, hmF2, and plasma frequency, fp, in the topside ionosphere at
low latitudes, derived from Intercosmos-19 satellite topside sounding data,
obtained from March 1979 to January 1981 and covering all longitudes, are
presented for quiet geomagnetic conditions in June and December solstices at
solar maximum for several local time intervals during the night. Based on these
maps, features of the equatorial anomaly (EA) at different longitudes and
their change during the night are considered. The maps show that averaged
foF2, hmF2, and fp longitudinal variations are rather complicated, their
structure looks wave-like with quasi-periods in longitude of about
75–100°,
similar to that on individual days revealed previously at low latitudes
using Intercosmos-19 data. Positions of the structure extrema in certain
longitude intervals are stable enough so that they are clearly seen in the
maps after averaging over a large number of measurements made on different
days and even in different years. Such structure seems to need at least five
harmonics for its description.
The maps derived from Intercosmos-19 data were compared with the maps given
by the IRI model. Along with general resemblance, essential distinctions between
them were found. Intercosmos-19 maps show more complicated and pronounced
longitudinal structure than IRI maps. They also show that at solar maximum,
in general, at night, EA is stronger and persists for a longer time (on
average, until 04:00 LT) than that presented in IRI model. Besides, much stronger
asymmetry between the characteristics of the EA northern and southern crests in
certain longitude intervals was revealed, most evident in hmF2
maps. |
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