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| Titel |
Analyses of zonal atmospheric excitation functions and their correlation with polar motion excitation functions |
| VerfasserIn |
J. Nastula, W. Kosek, B. Kolaczek |
| 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 ; 15, no. 11 ; Nr. 15, no. 11, S.1439-1446 |
| Datensatznummer |
250013007
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| Publikation (Nr.) |
 copernicus.org/angeo-15-1439-1997.pdf |
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| Zusammenfassung |
| The atmospheric influence on the Earth's,
rotation can be described by the effective atmospheric angular momentum (EAAM)
functions. In this study we focus on the analysis of short period variations of
the equatorial components of the zonal EAAM excitation functions χ1
and χ2 and their influence on similar variations of polar
motion. The global objective analysis data of the Japanese Meteorological Agency
for the period 1986–1992 were used to compute the EAAM excitation functions in
different latitude belts. Time- and latitude-variable amplitude spectra of
variations of these functions with periods shorter than 150 days, containing
pressure, pressure with the inverted barometric correction, and wind terms were
computed. The spectra show distinct latitude and time variations of the prograde
and retrograde oscillations which reach their maxima mainly in mid-latitudes.
Prograde and retrograde oscillations with periods of about 40–60 days and about
110–120 days are seen in the spectra of pressure terms of the equatorial
components of the zonal EAAM excitation functions. Additionally, correlation
coefficients and cross-spectra between variations of the geodetic polar motion
and equatorial components of the zonal EAAM excitation functions were computed
to identify the latitude belts of the globe over which atmospheric circulation
changes are correlated mostly with short period variations of the polar motion
excitation functions. The correlation coefficients vary in time and latitude and
reach maximum values in the northern latitudes from 50°N to 60°N.
In the cross-spectra between the polar motion excitation functions and pressure
terms of the zonal EAAM excitation functions there are peaks of common prograde
oscillations with the periods around 20, 30, 40–50, 60 and 80–150 days and of
common retrograde oscillations around 20, 30, 40 and 50–70 days. |
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