连续GPS观测中的相关噪声分析

Analysis on correlated noise in continuous GPS observations

分析了中国地壳运动观测网络GPS基准站位置时间序列中相关噪声的特性.利用最大似然估计反演了幂指数噪声的谱指数;考察了多种噪声模型,发现除闪烁噪声之外,约50%台站的东分量中的相关噪声可用"随机漫步噪声+一阶高斯-马尔可夫噪声"模型来描述,与其它分析机构产出的全球解并不一致,显示出处理策略的不同能够造成相关噪声的差异.白噪声和闪烁噪声的大小存在明显的地理分异,东南沿海台站的噪声要大于西北内陆台站.考虑相关噪声时,各站的速率估计方差要增大一个数量级以上,水平分量多在1mm/a以内,而垂向分量则较大.

We analyzed the characteristics of the correlated noise in position time series for fiducial GPS stations of the Crustal Motion Observation Network of China. The spectral index for power-law noise was derived using the maximum likelihood estimator. We took into account more types of noise models,and found that,besides flicker noise,about 50% east components can be described by a ‘random walk noise plus first-order Gauss-Markov noise’ model,which is inconsistent with the results from global solutions produced by other agencies. This reveals that the difference in processing strategy can induce varied correlated noise. The magnitudes of white noise and flicker noise are spatially correlated. The sites in southeastern coastal region have larger noise than inland northwestern ones. When considering the correlated noise,the estimation errors of velocity will increase by over an order. The velocity uncertainties are usually less than 1 mm/a for horizontal components and larger for vertical ones.