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| Titel |
Stratospheric semi-decadal oscillations in NCEP data |
| VerfasserIn |
H. G. Mayr, J. G. Mengel, F. T. Huang, E. R. Talaat, E. R. Nash, C. A. Reddy |
| 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. 8 ; Nr. 26, no. 8 (2008-08-01), S.2143-2157 |
| Datensatznummer |
250016175
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| Publikation (Nr.) |
 copernicus.org/angeo-26-2143-2008.pdf |
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| Zusammenfassung |
| An analysis of the National Centers for Environmental
Prediction (NCEP)/National Center for Atmospheric Research (NCAR) data is
presented to provide a more complete description of the stratospheric 5-year
semi-decadal (SD) oscillation (Mayr et al., 2007). The zonal-mean
temperature and zonal wind data from the Atmospheric Research R-1 analysis
are employed, covering the years from 1962 to 2002 in the altitude range
from 10 to 30 km. For diagnostic purposes, the data are separated into the
hemispherically symmetric and anti-symmetric components, and spectral
analysis is applied to identify the signatures of the SD oscillations.
Through the synthesis or filtering of spectral features, the SD modulations
of the annual oscillation (AO) and quasi-biennial oscillation (QBO) are
delineated. In agreement with the earlier findings, the magnitude of the SD
oscillation is more pronounced when the 30-month QBO dominates during the
years from 1975 to 1995. This is consistent with results from a numerical
model, which shows that such a QBO generates the SD oscillation through
interaction with the 12-month AO. In the zonal winds, the SD oscillation in
the NCEP data is confined to equatorial latitudes, where it modulates the
symmetric AO and QBO by about 5 m/s below 30 km. In the temperature data,
the effect is also seen around the equator, but it is much larger at polar
latitudes where the SD oscillation produces variations as large as 2 K. Our
data analysis indicates that the SD oscillation is mainly hemispherically
symmetric, and it appears to originate at equatorial latitudes where most of
the energy resides. |
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