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| Titel |
Diurnal variation in gravity wave activity at low and middle latitudes |
| VerfasserIn |
V. F. Andrioli, D. C. Fritts, P. P. Batista, B. R. Clemesha, D. Janches |
| 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 ; 31, no. 11 ; Nr. 31, no. 11 (2013-11-29), S.2123-2135 |
| Datensatznummer |
250086155
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| Publikation (Nr.) |
 copernicus.org/angeo-31-2123-2013.pdf |
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| Zusammenfassung |
| We employ a modified composite day extension of the Hocking (2005) analysis
method to study gravity wave (GW) activity in the mesosphere and lower
thermosphere using 4 meteor radars spanning latitudes from 7° S to
53.6° S. Diurnal and semidiurnal modulations were observed in GW
variances over all sites. Semidiurnal modulation with downward phase
propagation was observed at lower latitudes mainly near the equinoxes.
Diurnal modulations occur mainly near solstice and, except for the zonal
component at Cariri (7° S), do not exhibit downward phase
propagation. At a higher latitude (SAAMER, 53.6° S) these modulations are only
observed in the meridional component where we can observe diurnal variation
from March to May, and semidiurnal, during January, February, October
(above 88 km) and November. Some of these modulations with downward phase
progression correlate well with wind shear. When the wind shear is well
correlated with the maximum of the variances the diurnal tide has its largest
amplitudes, i.e., near equinox. Correlations exhibiting variations with tidal
phases suggest significant GW-tidal interactions that have different
characters depending on the tidal components and possible mean wind shears.
Modulations that do not exhibit phase variations could be indicative of
diurnal variations in GW sources. |
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