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Please use this identifier to cite or link to this item: http://hdl.handle.net/10204/3671

Title: Assessing the degree of synchronization between geophysical records using the method of instantaneous phase differences
Authors: Botai, OJ
Combrinck, WL
Sivakumar, V
Keywords: Geodetic parameters
Zenith tropospheric wet delay
Ensemble empirical mode decomposition
Phase differences
Noiseassisted data analysis methodology
11th South African Geophysical Association Biennial Conference
SAGA
Geophysics
Issue Date: Sep-2009
Publisher: South African Geophysical Association
Citation: Botai, OJ, Combrinck, WL and Sivakumar, V. 2009. Assessing the degree of synchronization between geophysical records using the method of instantaneous phase differences. 11th South African Geophysical Association (SAGA) Biennial Conference and Exhibition, Swaziland, 16-18 September 2009, pp 588-593
Abstract: Recovering geodetic parameters such as tropospheric delay and geodetic site positions and monitoring their variations in time has important applications for studying the processes of the dynamic earth. Geodetic position time series exhibit non-linear motions that are associated with seasonal signals caused by loading effects, and seismic deformation processes such as earthquakes etc. This implies that the fluctuations in the station coordinates and tropospheric parameters could be synchronized because they are driven by common underlying processes. In the analysis of space geodetic measurements, space geodetic solutions are often co-assessed in order to determine geophysical signals present in both parameters. The main objective of the current analysis is to determine the linkage between temporal structure of the zenith tropospheric delay and the geodetic station height coordinates fluctuations in the time-frequency-energy space. The temporal structures of the combined solution of the zenith tropospheric wet delay (ZWD) and the geodetic station height at the Hartebeesthoek geodetic station (HartRAO) have been studied. The oscillation patterns in these geophysical signals have been analysed by using the noiseassisted data analysis (NADA) methodology known as ensemble empirical mode decomposition (EEMD). The instantaneous phase differences among the associated modes of the intrinsic mode functions (IMFs) have been computed and used to assess the degree of synchronisation between the two series. The results showed that the ZWD and the HartRAO geodetic station height show modes that are temporally correlated and some of the IMF modes exhibit temporal structures that can be associated with both local and global forcing mechanisms.
Description: 11th South African Geophysical Association (SAGA) Biennial Conference and Exhibition, Swaziland, 16-18 September 2009
URI: http://hdl.handle.net/10204/3671
ISBN: 9780620446020
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