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| Titel |
Planetary wave seasonality from meteor wind measurements at 7.4° S and 22.7° S |
| VerfasserIn |
L. R. Araújo, L. M. Lima, P. P. Batista, B. R. Clemesha, H. Takahashi |
| 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 ; 32, no. 5 ; Nr. 32, no. 5 (2014-05-22), S.519-531 |
| Datensatznummer |
250121059
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| Publikation (Nr.) |
 copernicus.org/angeo-32-519-2014.pdf |
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| Zusammenfassung |
| In this study we have used wind observation data from the mesosphere and lower
thermosphere (MLT) region, obtained from meteor radar measurements in São
João do Cariri (7.4° S, 36.5° W) from July 2004 to
December 2008 and in Cachoeira Paulista (22.7° S,
45.0° W) from January 2002 to July 2006 and from September 2007 to
November 2008. From the spectral analysis it was possible to identify the
presence of planetary-scale oscillations in the hourly winds for the two
latitudes and to study their transient character, which allowed elaboration
of a climatology of planetary oscillation signatures. Planetary waves with
periods near 2-days, 6–7 days, and 16 days were focussed on in this study. The
quasi-2-day waves in the meteoric winds showed a seasonal cycle, with intense
amplitudes occurring after the austral summer solstice and extending until
the end of the season. The vertical wavelengths of the 2-day wave over
Cachoeira Paulista were larger than those at São João do Cariri. A
possible modulation of the quasi-2-day wave amplitudes by the quasi-biennial oscillation (QBO) has been
observed only at São João do Cariri. The 6–7 day oscillations
presented more intense amplitudes during August–November but were present
with lower amplitudes during March–April at both sites. The 6–7 day vertical
wavelengths over São João do Cariri were larger than at Cachoeira
Paulista. The 6–7 day amplitudes exhibited intra-seasonal and annual
behavior, however, there was no clear evidence of QBO modulation. The 16-day
oscillations showed a seasonal cycle at São João do Cariri, with
amplifications from austral spring to mid-summer and weaker amplitudes from
autumn until early winter, however, there was no clear seasonality over Cachoeira
Paulista. The 16-day vertical wavelengths have assumed values of λz
~ 45–85 km over both sites. 16-day wave amplitudes at the two sites
showed different long-term behaviors. |
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