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| Titel |
First simultaneous lidar observations of sodium layers and VHF radar observations of E-region field-aligned irregularities at the low-latitude station Gadanki |
| VerfasserIn |
S. Sridharan, A. K. Patra, N. Venkateswara Rao, G. Ramkumar |
| 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 ; 27, no. 9 ; Nr. 27, no. 9 (2009-09-01), S.3411-3419 |
| Datensatznummer |
250016638
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| Publikation (Nr.) |
 copernicus.org/angeo-27-3411-2009.pdf |
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| Zusammenfassung |
| Simultaneous observations of atmospheric sodium (Na) made by a resonance
lidar and E-region field-aligned-irregularities (FAI) made by the Indian MST
radar, both located at Gadanki (13.5° N, 79.2° E) and horizontal winds
acquired by a SKiYMET meteor radar at Trivandrum (8.5° N, 77° E) are
used to investigate the relationship among sodium layer, FAI and neutral
winds in the mesosphere and lower thermosphere region. The altitudes and
descent rates of higher altitude (~95 km) Na layer and FAI agree quite
well. The descending structures of the higher altitude Na layer and FAI are
found to be closely related to the diurnal tidal phase structure in zonal
winds observed over Trivandrum. At lower altitudes, the descent rate of FAI
is larger than that of Na layer and zonal tidal phase. These observations
support the hypothesis that the metallic ion layers are formed by the zonal
wind shear associated with tidal winds and subsequently get neutralized to
manifest in the form of descending Na layers. The descending FAI echoing
layers are manifestation of the instabilities setting in on the ionization
layer. In the present observations, the altitudes of occurrence of Na layer
and FAI echoes being low, we surmise that it is quite possible that the FAI
echoes are due to the descent of already formed irregularities at higher
altitudes. |
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