We investigate geocenter motion time series derived from the combined solutions and six individual analysis center (AC) solutions of the International GNSS Service (IGS) second reprocessing campaign using the network shift approach, in terms of noise content, long-term trends, periodic and aperiodic variations. We assess these GNSS geocenter motion estimates by comparison with independent estimates from satellite laser ranging (SLR). The GNSS geocenter time series exhibit correlated noise which is better represented by a white plus power–law noise model in the X and Y directions, and by a white plus first-order autoregressive (or generalized Gauss–Markov) noise model in the Z direction. The GNSS geocenter time series include expected seasonal variations, but also spurious draconitic signals, particularly in the Z direction. GNSS annual geocenter motion estimates are in reasonable agreement with SLR estimates in the X and Y directions. In the Z direction, however, the annual signals derived from the IGS solutions disagree with SLR estimates, except for three particular ACs. This suggests that the different orbit modeling strategies used by these ACs may constitute an improvement over the conventional strategy employed by the other ACs. The background noise in GNSS and SLR geocenter time series finally appears to be correlated, suggesting that it might partly reflect real, aperiodic geocenter motion.

中文翻译：

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IGS第二次再处理对地球中心运动估计的评估

我们使用噪声偏移，长期趋势，周期性和周期性，研究了使用网络移位方法从国际GNSS服务（IGS）第二次再处理活动的组合解决方案和六个单独的分析中心（AC）解决方案得出的地球中心运动时间序列。非周期性变化。我们通过与来自卫星激光测距（SLR）的独立估计值进行比较，来评估这些GNSS地球中心运动的估计值。所述GNSS地心的时间序列显示出其更好通过在白色加幂律噪声模型表示相关噪声X和ÿ方向，并且由白色加一阶自回归（或广义高斯-马尔可夫）噪声模型在Ž方向。GNSS地球中心时间序列包括预期的季节变化，但也包括虚假的极端信号，尤其是在Z方向。GNSS的年度地球中心运动估算值与X和Y方向上的SLR估算值在合理范围内一致。但是，在Z方向上，除了三个特定的AC外，从IGS解决方案得出的年度信号与SLR估算不一致。这表明这些AC使用的不同的轨道建模策略可能构成对其他AC使用的常规策略的改进。GNSS和SLR地心时间序列中的背景噪声最终似乎是相关的，这表明它可能部分反映了真实的非周期性地心运动。