Wavelet Approach to Study Gravity Pole Tide
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Abstract
Wavelet analysis for filtering is used to improve estimation of gravity variations induced by Chandler and annual wobble.This method eliminates noise in superconducting gravimeter(SG) records with band pass filters derived from Daubechies wavelet.The SG records at Brussels are analyzed.First,the Earth tides are removed from the observed data by using synthetic tides,and then the gravity residuals are filtered into a narrow period band of 256-512 d by a wavelet band pass filter.These data are submitted to least-square method for estimating the gravimetric factor of the Chandler and annual wobble.After processed by wavelet filtering,SG records can provide amplitude factors δ and phase lags κ of the two wobbles 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.
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