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| Titel |
Thermospheric zonal temperature gradients observed at low latitudes |
| VerfasserIn |
P. R. Fagundes, Y. Sahai, J. A. Bittencourt |
| 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 ; 19, no. 9 ; Nr. 19, no. 9, S.1133-1139 |
| Datensatznummer |
250014322
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| Publikation (Nr.) |
 copernicus.org/angeo-19-1133-2001.pdf |
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| Zusammenfassung |
Fabry-Perot
interferometer (FPI) measurements of thermospheric temperatures from the
Doppler widths of the OI 630 nm nightglow emission line have been carried out
at Cachoeira Paulista (23° S, 45° W, 16° S dip latitude), Brazil. The
east-west components of the thermospheric temperatures obtained on 73 nights
during the period from 1988 to 1992, primarily under quiet geomagnetic
conditions, were analyzed and are presented in this paper. It was observed that
on 67% of these nights, the temperatures in both the east and west sectors
presented similar values and nocturnal variations. However, during 33% of the
nights, the observed temperatures in the west sector were usually higher than
those observed in the east sector, with zonal temperature gradients in the
range of 100 K to 600 K, over about an 800 km horizontal distance. Also, in
some cases, the observed temperatures in the east and west sectors show
different nocturnal variations. One of the possible sources considered for the
observed zonal temperature gradients is the influence of gravity wave
dissipation effects due to waves that propagate from lower altitudes to
thermospheric heights. The observed zonal temperature gradients could also be
produced by orographic gravity waves originated away, over the Andes Cordillera
in the Pacific Sector, or by dissipation of orographic gravity waves generated
over the Mantiqueira Mountains in the Atlantic sector by tropospheric
disturbances (fronts and/or subtropical jet streams).
Key words. Atmospheric composition
and structure (air-glow and aurora; thermosphere - composition and chemistry)
Ionosphere (equatorial ionosphere) |
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