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In this paper,we analyze the time series of site coordinates of 27 continuously monitoring GPS sites covered bythe Crustal Movement Observation Network of China over the whole country.The data are obtained in the periodfrom the beginning of the observation to the November of 2005.On the basis of data processing,we analyze thepower spectrum density of coordinate component noise at each site and calculate the spectral indexes manifestingthe noise property of each component.The spectral indexes indicate that for most sites,the noise of time series ofeach coordinate component can be addressed by the model of white noise+flicker noise;and for a small amountof sites,it can be described by the model of white noise+flicker noise+random walk noise.We also quantita-tively estimate each noise component in the model by using the criterion of maximum likelihood estimation.Theresult shows that the white noise in the time series of GPS site coordinates does not constitute the main part ofnoise.Therefore,the error estimation of site movement parameters is usually too small,or too optimistic if weconsider the white noise only.Correspondingly,if this factor is not fully considered in explaining these movementparameters,it might mislead the readers.
In this paper, we analyze the time series of site coordinates of 27 ever monitoring GPS sites covered by the Crustal Movement Observation Network of China over the whole country. The data are obtained in the periodfrom the beginning of the observation to the November of 2005.On the basis of data processing, we analyze the power spectrum density of coordinate component noise at each site and calculate the spectral indexes manifesting the noise property of each component. The spectral indexes indicate that for most sites, the noise of time series of generator coordinate components can be addressed by the model of white noise + flicker noise; and for a small amount of sites, it can be described by the model of white noise + flicker noise + random walk noise. We also quantita-tively estimate each noise component in the model by using the criterion of maximum likelihood estimation. Theresult that the white noise in the time series of GPS site coordinates does not constitute the main part ofnoise.Theref ore, the error estimation of site movement parameters is usually too small, or too optimistic if weconsider the white noise only. Corrrespondingly, if this factor is not fully considered in explaining these movementparameters, it might mislead the readers.