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| Titel |
Short periodic variations of polar motion and hemispheric atmospheric angular momentum excitation functions in the period 1984-1992 |
| VerfasserIn |
J. Nastula |
| 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 ; 13, no. 2 ; Nr. 13, no. 2, S.217-225 |
| Datensatznummer |
250011751
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| Publikation (Nr.) |
 copernicus.org/angeo-13-217-1995.pdf |
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| Zusammenfassung |
| Short periodic oscillations with the periods
from 10 up to 110 days of the hemispheric components of effective atmospheric
angular momentum (EAAM) excitation function and their correlation with polar
motion excitation function have been analyzed. The EAAM data of the Japan
Meteorological Agency (JMA) computed for the two hemispheres and the very long
baseline interferometry (VLBI) polar motion NGS 92 R01 data (NGS 1992),
determined by the National Geodetic Survey were applied. The distinct
oscillations with periods of about 28, 35-55 and 60-80 days were detected in the
χy-component of both polar motion excitation
function and northern EAAM excitation functions containing wind and pressure,
with and without inverted barometric correction terms. The χy-component
of the polar motion excitation function is significanly correlated (correlation
coefficient equal to 0.55-0.75) with the χy-components
of the northern EAAM excitation functions mentioned above, which are mostly
induced by the atmospheric circulation over lands. No meaningful correlation
between polar motion excitation function and the southern EAAM excitation
functions was found. The χx-components of the EAAM
and polar motion excitation functions are not significantly correlated. The
strong short periodic variation of the length of day (LOD) and
χy in the early 1988 seems to be caused by the
above-mentioned 35-55 days oscillations of the northern hemisphere atmosphere.
This variation can be related to the rapid passing from the El Niño to the La
Niña phenomenon or from the minimum to the maximum in the Southern Oscillation
Index in 1987-1989. |
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