In the geocenter motion determination using the Global Navigation Satellite Systems (GNSS), satellite clock offsets are usually estimated as white noise process. The correlation between geocenter coordinates (GCC) and the epoch-wise satellite clocks brings inferior GCC estimates, especially for the Z component. In this contribution, satellite clock offsets are described by the polynomial model, and the deviation of the model from the truth is estimated as a random parameter whose process noise is described by the variogram. Based on 3.7 years of BDS, Galileo and GPS observations from 98 global stations, we investigate the impact of the atomic clock model on GCC estimates. After employing the proposed model, the formal errors of GCC-Z component are reduced by 23–46%, 15–31% and 3–9% for BDS, Galileo and GPS, respectively. When the 7-parameter extended empirical CODE orbit model with the a priori box-wing model (BE7) is used, the atomic clock model reduces the correlation of the B_1C parameter and GCC-Z component by 0.28, 0.23 and 0.07 for BDS, Galileo and GPS, respectively. Besides, a mitigation of about 60% is obtained at the 3rd and 5th BDS draconitic harmonics and a mitigation of 55% at the 3rd Galileo draconitic harmonic for the GCC-Z component. The proposed model also contributes to reduce the annual amplitudes of single BDS, Galileo and GPS solutions, improving the agreement with the Satellite Laser Ranging solutions. As an additional verification, the resulting satellite orbits are also improved by satellite clock modeling. When the BE7 model is applied, the day boundary discontinuities of daily orbits are reduced by 3.4–3.6%, and the RMS of orbit differences relative to the ESA precise orbits is reduced by 8.2–8.5% for BDS and Galileo.

在使用全球导航卫星系统（GNSS）确定地心运动时，卫星时钟偏移通常被估计为白噪声过程。地心坐标 (GCC) 和历元卫星时钟之间的相关性带来了较差的 GCC 估计，特别是对于 Z 分量。在此贡献中，卫星时钟偏移由多项式模型描述，模型与真实情况的偏差被估计为随机参数，其过程噪声由变差函数描述。基于 98 个全球站点 3.7 年的 BDS、伽利略和 GPS 观测，我们研究了原子钟模型对 GCC 估计的影响。采用所提出的模型后，BDS、Galileo 和 GPS 的 GCC-Z 组件的形式误差分别减少了 23-46%、15-31% 和 3-9%。当使用带有先验盒翼模型（BE7）的7参数扩展经验CODE轨道模型时，原子钟模型将B _1C 参数与GCC-Z分量的相关性降低了0.28， BDS、伽利略和 GPS 分别为 0.23 和 0.07。此外，GCC-Z 分量在北斗 3 次和 5 次龙脉谐波处获得约 60% 的缓解，在伽利略 3 次龙脉谐波处获得 55% 的缓解。所提出的模型还有助于降低单个BDS、伽利略和GPS解决方案的年振幅，提高与卫星激光测距解决方案的一致性。作为额外的验证，卫星时钟模型也改进了由此产生的卫星轨道。应用BE7模型后，北斗和伽利略日轨道日边界不连续性降低了3.4%~3.6%，相对于欧空局精密轨道的轨道差均方根降低了8.2%~8.5%。