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| Titel |
Seasonal and interannual variations of gravity wave activity in the low-latitude mesosphere and lower thermosphere over Tirunelveli (8.7° N, 77.8° E) |
| VerfasserIn |
S. Sridharan, S. Sathishkumar |
| 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 ; 26, no. 11 ; Nr. 26, no. 11 (2008-10-21), S.3215-3223 |
| Datensatznummer |
250016266
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| Publikation (Nr.) |
 copernicus.org/angeo-26-3215-2008.pdf |
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| Zusammenfassung |
| The Mesosphere and Lower Thermosphere (MLT) winds acquired by medium
frequency (MF) radar at Tirunelveli (8.7° N, 77.8° E) for the years
1993–2007 are used to study seasonal and interannual variabilities of
gravity wave (GW) variances in the altitude region 84–94 km. The GW
variances in zonal and meridional winds show semiannual oscillation with
maximum variance during March–April and August–September and minimum during
June–July and November–December months. The wind variances, in general, are
observed to be enhanced during and after the year 1998 and they undergo
large interannual variability, in particular, during spring equinox months.
An enhancement of GW variances is observed during spring equinox months
of the years 2000, 2004 and 2006. These larger GW enhancements, most of the
times, coincide with eastward phase of zonally averaged stratospheric QBO at
30 hPa over equator and sudden stratospheric warming occurred at high
latitudes. From the zonal and meridional variances, the perturbation
ellipses are calculated and they show that the predominant direction of
propagation of gravity waves is in SE-NW plane. |
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