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Analysis of Long Time Series of Polar Motion

Published online by Cambridge University Press:  12 April 2016

H. Schuh
Affiliation:
Deutsches Geodätisches Forschungsinstitut (DGFI)Marstallplatz 8, 80539 München, Germanye-mail:[email protected]
B. Richter
Affiliation:
Deutsches Geodätisches Forschungsinstitut (DGFI)Marstallplatz 8, 80539 München, Germanye-mail:[email protected]
S. Nagel
Affiliation:
Deutsches Geodätisches Forschungsinstitut (DGFI)Marstallplatz 8, 80539 München, Germanye-mail:[email protected]

Abstract

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Two long time series of polar motion were analysed with respect to a linear drift, decadal variations, Chandler wobble and annual wobble: the C01 series published by the International Earth Rotation Service (IERS) and the pole series which J. Vondrák, obtained by re-analysis of the classical astronomical observations using the HIPPARCOS reference frame (1899.7–1992.0). By a least-squares fit the linear drift of the pole, usually called ‘secular polar motion,’ was determined to 3.31 milliarcseconds/year (mas/yr) toward 76.1° West longitude. For this fit the a priori correlations within each pair of pole coordinates were taken into account, and the weighting function was calculated by estimation of empirical variance components. The decadal variations of the pole path were determined by Fourier analysis. Using a sliding window analysis, the variability of the periods, the amplitudes and the phases of the Chandler wobble and annual wobble was investigated. The variances of the results and the number of iterations needed to get a convergence in the nonlinear approach show that the new time series by Vondrák is more homogeneous and consistent than the IERS C01 series.

Type
Part 3. Observational Techniques for Polar Motion
Copyright
Copyright © Astronomical Society of the Pacific 2000

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