Coordinate Time Series of IGS Station in China Based on the Combination of Wavelet Spectral and Variance Component Estimation

Wavelet spectral analysis is employed in this paper to determine the frequency components and their variations over time in coordinating time series of IGS stations in China. Then least-squares variance component estimation (LS-VCE) is adopted to analyze motion characteristics of stations in China in different periods under the assumed model of white and flicker noise. The results indicate that motion characteristics of IGS station in China are seasonally varied in different periods. The variation of the vertical velocity of URUM station is greater than 4 mm, while velocity changes more than 2 mm for horizontal component of BJFS and CHAN. And the rest are no more than 2 mm. There are also differences in the amplitude of the annual and semi-annual signals. Among them, BJFS has the largest change in vertical component, which is more than 5 mm; In addition, weaker periodic items are discovered in some segment of the time series. Though, due to their little impact on the result of parameter estimation, they are discarded along the process. Moreover, the fact that the estimations of the parameters for one station are not consistent in different segments of the time series may reflect patterns of geophysical effects on certain stations over time such as plate motion.