Wavelet analysis of the Earth center of mass time series determined by satellite techniques

Popiński²,

Wnęk

et al. 2019

Pure Appl. Geophys.

Self Cite

The goal of this paper is to determine and analyze the common geocenter signal from the geocenter coordinates based on four independent techniques: Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS), Global Navigation Satellite System (GNSS), Gravity Recovery And Climate Experiment with the ocean bottom pressure model, and Satellite Laser Ranging, and to analyze the residuals as the differences between these geocenter coordinates and their common signal. Another objective of this paper is to compute variable amplitudes and phases of the annual and semi-annual oscillations in the geocenter coordinates of these techniques by the combination of the Fourier Transform Band Pass Filter (FTBPF) with the Hilbert Transform (FTBPF + HT) and to compare their mean values with those obtained by other authors. It was assumed that the geocenter time series of individual techniques consist of the common signal of geocenter motion, systematic errors resulting from orbital modeling and noise. Generally, the annual oscillation amplitudes in these techniques computed by the FTBPF + HT vary in time and their mean values are of the order of 2 mm for the X coordinate, 2.4–3.6 mm for the Y coordinate and 2.8–5.6 mm for the Z coordinate and the semi-annual oscillation amplitude is variable and about two times smaller than the annual one. The phases of these two oscillations are also variable, there are differences in their mean values for different techniques and the semi-annual oscillation phases changes throughout the entire phase range. To detect the common geocenter signal the wavelet-based semblance filtering (WBSF) method was applied. The weighted mean model was computed from all geocenter coordinate pairs from individual techniques assuming weights as inversely proportional to the variances of differences between the geocenter coordinates and their corresponding WBSF outputs. The average and median models computed from these outputs show a good agreement with the weighted mean model and generally, the average amplitudes of the annual signal in these models are of the order of 2 mm in each geocenter coordinate. The FTBPF amplitude spectra of these models reveals the retrograde annual oscillation in the XY equatorial plane. The FTBPF and FTBPF + HT amplitude spectra of geocenter time series and their residuals show mainly the maxima of different heights in the annual frequency band. The annual oscillations left in all residuals and oscillations with period less than ~ 120 days in DORIS and GNSS amplitude spectra may be caused by systematic errors of techniques resulting from mis-modeling of satellite orbits.

Section: Motivation and Goals Of This Papermentioning

confidence: 99%

Section: Stochastic Model Of the Geocenter Motionmentioning

confidence: 99%

Analysis of Systematic Errors in Geocenter Coordinates Determined From GNSS, SLR, DORIS, and GRACE

Popiński²,

Wnęk

et al. 2019

Pure Appl. Geophys.

Self Cite

“…The spectra-temporal wavelet semblance with the application of the modified Morlet wavelet function enables computation of correlation coefficients between the centre of mass time series determined by Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS), Global Navigation Satellite Systems (GNSS) and Satellite Laser Ranging (SLR) techniques as a function of time and frequency (Kosek et al, 2014). The highest positive semblance values occur in the XY equatorial plane for the retrograde annual oscillation in the GNSS and SLR data as well as prograde annual oscillation between DORIS and other two techniques.…”

Section: Geocenter Motionmentioning

confidence: 99%

Earth rotation and geodynamics

Bogusz

Brzeziński

Geodesy and Cartography

et al. 2015

This paper presents the summary of research activities carried out in Poland in 2011-2014 in the field of Earth rotation and geodynamics by several Polish research institutions. It contains a summary of works on Earth rotation, including evaluation and prediction of its parameters and analysis of the related excitation data as well as research on associated geodynamic phenomena such as geocentre motion, global sea level change and hydrological processes. The second part of the paper deals with monitoring of geodynamic phenomena. It contains analysis of geodynamic networks of local, and regional scale using space (GNSS and SLR) techniques, Earth tides monitoring with gravimeters and water-tube hydrostatic clinometer, and the determination of secular variation of the Earth’ magnetic field.

“…This type of filtering of the geocenter time series has been widely described by Kosek et al [2014].…”

Section: Wavelet Based Semblance Filteringmentioning

confidence: 99%

Corrections to sea level anomalies data due to geocenter motion

Wnęk

Zbylut-Górska

2015

GLL

Self Cite

SummaryThe objective of this paper is computation of the corrections to sea level anomaly data due to center of Earth mass variations. The geocenter motion model was computed from the center of mass coordinates data determined from observations of space geodetic techniques such as Satellite Laser Ranging (SLR), Global Navigation Satellite System (GNSS) and Doppler Orbitography and Radiopositionig Integrated on Satellite (DORIS). In order to compute the geocenter motion model the center of mass coordinates data were filtered using wavelet based semblance filtering which allows computing a common signal in two time series. Based on determined geocenter motion model a correction to sea level anomalies (SLA) data due to geocenter motion was determined. This kind of correction to sea level anomaly data is of the order of few millimetres and should be applied to altimetric measurements to refer them to the International Terrestrial Reference Frame (ITRF) Origin considered as the center of figure.