Call number:
21/STR 02/13
In:
Scientific technical report
Description / Table of Contents:
Chandler and annual wobbles based on space-geodetic measurements: In this study, we examine the major components of polar motion, focusing on quantifying their temporal variability. In particular, by using the combined Earth orientation series SPACE99 computed by the Jet Propulsion Laboratory (JPL) from 1976 to 2000 at daily intervals, the Chandler and annual wobbles are separated by recursive band-pass filtering of the ?1- and ?2 -components. Then, for the trigonometric, exponential, and elliptic forms of representation,the parameters including their uncertainties are computed at epochs using quarterly sampling. The characteristics and temporal evolution of the wobbles are presented, as well as a summary of estimates of different parameters for four epochs.
Description / Table of Contents:
Polar motions with a half-Chandler period and less in their temporal variability: Our study focuses on the observed higher-frequency polar motions that are substantially smaller than the Chandler and annual wobbles. Here, the combined Earth orientation series SPACE99 from 1976 to 2000 with one-day sampling is used as input data, after removing the low-frequency, the Chandler and annual terms. We applied a dataprocessing procedure including four steps, each computing the amplitude spectrum by a Fast Fourier Transform in order to reveal the periodic signals in the residual motions, and then separating their components from the residual time series by band-pass filtering. In particular, the oscillations have the following periods: Semi-Chandler and semi-annual periods and those of order four, three, two, and one and a half months, as well as quasi-biennial and 300-day periods. We show to what extent the observed polar motions are irregularly occurring. A very small polar motion signal with the period ofone month is still found in the remaining motions.
Type of Medium:
GFZ publications
Pages:
23 S.
Series Statement:
Scientific technical report / Geoforschungszentrum Potsdam 02/13
URL:
http://ebooks.gfz-potsdam.de/pubman/item/escidoc:8590:3/component/escidoc:10639/0213.pdf
Classification:
Geodynamics
Language:
English
Location:
Reading room
Branch Library:
GFZ Library
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