Estimation of the pole tide gravimetric factor at the chandler period through wavelet filtering

Abstract

SUMMARY Wavelet analysis for filtering is used to improve estimation of gravity variations induced by Chandler wobble. This method eliminate noise in superconducting gravimeter (SG) records with bandpass filters derived from Daubechies wavelet. The SG records at four European stations (Brussels, Membach, Strasbourg and Vienna) are analysed in this study. First, the earth tidal constituents are removed from the observed data by using synthetic tides, then the gravity residuals are filtered into a narrow period band of 256–512 d by a wavelet bandpass filter. These data are submitted to three regression analysis methods for estimating the gravimetric factor of the Chandler wobble. After processing by wavelet filtering, SG records can provide amplitude factors δ and phase lags κ of the Chandler wobble with much smaller mean square deviation (MSD) than these provided by former studies. It is mainly because the wavelet method can effectively eliminate instrumental drift and provide smoothed data series for the regression analysis.

Determination of gravimetric parameters of the gravity pole tide using observations recorded with superconducting gravimeters

“…The gravity effect induced by the ocean pole tide is calculated on the basis of an equilibrium ocean pole tide . Recent results for 4 European stations (Brussels, Membach, Strasbourg, Vienna) given by Hu et al (2007) show the advantage of wavelet filtering in the estimation of the pole tide gravimetric factor at Chandler period. In this study, the atmospheric gravity effect is calculated with a frequencydependent admittance with station air pressure observations.…”

Loading effect of a self-consistent equilibrium ocean pole tide on the gravimetric parameters of the gravity pole tides at superconducting gravimeter stations

“…Thanks to these characteristics, long period gravity tides have been determined (Ducarme et al, 2004;Boy et al, 2006;Hu et al, 2006;Harnisch and Harnisch, 2006), and the gravity pole tide has also been observed (Hinderer and Legros, 1989;Boy et al, 1998;Loyer et al, 1999;Xu et al, 2004;Ducarme et al, 2006;Hu et al, 2007). The gravity pole tides are the gravity variations induced by polar motion of the Earth, which almost entirely consists of the annual wobble (AW) and the Chandler wobble (CW) that has a period of approximately 14 months.…”

Influence of liquid core dynamics on rotational modes

“…Different analyses of the same data set of polar motion give different results: the CW period may be single, double, multiple, or variable in time. Since that paper has been published, new analyses have been made (Guo et al 2005b; Hu et al 2007; Pan 2007) but no definite conclusion has been reached yet.…”