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| Titel |
Nonmigrating tidal signals in the upper thermospheric zonal wind at equatorial latitudes as observed by CHAMP |
| VerfasserIn |
K. Häusler, H. Lühr |
| 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. 7 ; Nr. 27, no. 7 (2009-07-03), S.2643-2652 |
| Datensatznummer |
250016577
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| Publikation (Nr.) |
 copernicus.org/angeo-27-2643-2009.pdf |
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| Zusammenfassung |
| The accelerometer onboard CHAMP enables us to derive the thermospheric zonal
wind at orbit altitudes (~400 km). Numerous equatorial overflights
(~45 250) are used to investigate the influence of nonmigrating tides
on the thermospheric zonal wind. In a previous study a so called "wave-4"
longitudinally signal observed in the satellite frame was identified in the
zonal wind residuals during equinox. Using four years of data (2002–2005), we
determine the annual variation of this prominent feature which is strongest
during the months of July through October and has a smaller second maximum
during March/April. Due to the large data set we were able to separate the
observed wavenumbers into the tidal components. Thereby, we can identify the
eastward propagating diurnal tide with zonal wavenumber s=3 (DE3) as the
prime cause for the observed wave-4 pattern in the zonal wind. Analyzing the
zonal wind along the geographic and the dip equator revealed that the largest
amplitudes of DE3 are found along the dip equator. Besides DE3 we present the
full spectrum of nonmigrating tides in the upper thermosphere. |
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