Stacking gravity tide observations in central Europe for the retrieval of the complex eigenfrequency of the nearly diurnal free-wobble |
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Authors: | J Neuberg J Hinderer W Zürn |
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Institution: | Geophysikalisches Institut, Universität Karlsruhe, Hertz str. 16, D-7500 Karlsruhe 21, West Germany;Institut de Physique du Globe, 5, rue RenéDescartes, F-67084 Strasbourg, France;Geowissenschaftliches Gemeinschaftsobservatorium der Universitäten Karlsruhe/Stuttgart, Heubach 206, D-7620 Wolfach, West Germany |
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Abstract: | We have used tidal gravity measurements from six stations in central Europe to investigate the resonance in the diurnal tidal band, caused by inertial coupling between the mantle and outer core of the Earth. By the use of stacking it was possible to determine the eigenfrequency and quality factor of this eigenmode, commonly called the 'nearly diurnal free-wobble'. We assessed the effect of systematic errors from the ocean correction to the tidal measurements employing a Monte-Carlo method. The observed eigenfrequency is 1 + 1/(434 ± 7) cycles per sidereal day, and is significantly higher than predicted by theories. The observed quality factor is (2.8 ± 0.5) × 103. |
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Keywords: | wobble diurnal resonance gravity tides complex eigenfrequency |
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