中国大陆GPS连续站时间序列噪声分析

GPS位置时间序列中不仅存在白噪声，还存在大量的闪烁噪声。如果只使用纯白噪声的协方差矩阵来估计速度，速度的不确定性会被严重低估。利用频谱分析和极大似然估计的方法对中国大陆地壳运动观测网络的264个GPS连续站长达20 a的GPS坐标时间序列进行了噪声分析，并计算出每个测站速度的不确定性。结果表明东、北及垂直方向上呈现了不同的噪声特性。频谱分析估计的光谱指数高于极大似然估计的指数，但均在−1附近，表明主要的噪声模型是白噪声加闪烁噪声。使用不同的噪声模型计算的速度不确定性存在较大差异，在东、北及垂直方向上，最优噪声模型计算的速度不确定性分别是只使用白噪声模型的(11.5±2.1)倍、(12.9±2.9)倍和(14.8±3.7)倍。利用极大似然估计方法与FOGMEx方法所计算的速度差距不大，在东、北及垂直方向上，利用极大似然估计方法所计算的速度不确定性分别是FOGMEx方法的(2.8±1.5)倍、(1.5±0.7)倍和(3.5±2.8)倍。

Noise Analysis of Continuous GPS Time Series in China Continent

There is not only white noise in GPS position time series, but also a lot of flicker noise. If only the covariance matrix of pure white noise is used to estimate the velocity, the velocity accuracy will be seriously overestimated. Spectrum analysis and maximum likelihood estimation methods are used to analyze the 20-year GPS coordinate time series of 264 GPS continuous stations of the Chinese Continental Crustal Movement Observation Network, and the velocity accuracy of each station calculated. The results show that there are different noise characteristics in E, N and U directions. The spectral exponents estimated by spectral analysis are higher than those estimated by maximum likelihood, but they are all around −1, which indicates that the main noise model is white noise plus flicker noise. The velocity accuracy calculated by different noise models is quite different. In the east, the north, and the vertical directions, the velocity accuracy calculated by the optimal noise model is, respectively, (11.5±2.1), (12.9±2.9), and (14.8±3.7) times that of the white noise model only. The velocity between maximum likelihood estimation method and FOGMEx method is not very different. In the east, the north, and the vertical directions, the velocity accuracy calculated by the maximum likelihood estimation method is (2.8±1.5), (1.5±0.7), and (3.5±2.8) times that of the FOGMEx method, respectively.