Precise knowledge of geocenter motion, i.e., the relative motion between the Earth’s center of mass (CM) and the center of figure of the Earth’s surface (CF), is crucial to high-stakes geodetic applications such as sea-level rise monitoring with satellite altimetry or the establishment of regional and global mass budgets with satellite gravimetry. The computation of the latest release of the International Terrestrial Reference Frame, ITRF2020, involved the estimation of a field of seasonal motions for a global network of geodetic stations, expressed with respect to CM, as sensed by satellite laser ranging, from which the translational part represents seasonal geocenter motion. This paper presents two different methods to isolate seasonal geocenter motion from the field of ITRF2020 seasonal station motions, among which a new method based on a direct weighted average of seasonal station motions, with station-specific weights chosen so as to provide a better approximation of CF than the standard network shift approach. The ITRF2020 annual geocenter motion model thus obtained is then compared with other recent geodetic and geophysical estimates. Although different sub-groups of estimates with relatively good internal consistency may be identified, the overall scatter of recent geodetic estimates remains at the level of several mm, i.e., close to the amplitude of annual geocenter motion itself. Efforts toward reconciling seasonal geocenter motion estimates therefore still appear necessary. Meanwhile, it would seem safe to assume that seasonal geocenter motion models, in particular those currently used in satellite altimetry and satellite gravimetry, are still uncertain.

精确了解地心运动，即地球质心 (CM) 与地球表面图形中心 (CF) 之间的相对运动，对于卫星海平面上升监测等高风险大地测量应用至关重要高度测量或通过卫星重力测量建立区域和全球质量预算。最新发布的国际地球参考系 ITRF2020 的计算涉及对全球大地测量站网络的季节性运动场的估计，以卫星激光测距感测到的 CM 表示，其中平移部分代表季节性地心运动。本文提出了两种不同的方法，将季节性地心运动与 ITRF2020 季节性台站运动领域隔离，其中一种基于季节性台站运动直接加权平均值的新方法，选择特定于台站的权重，以便提供更好的近似值CF比标准的网络移位方式要好。然后将由此获得的 ITRF2020 年度地心运动模型与其他最近的大地测量和地球物理估计进行比较。尽管可以识别出具有相对良好内部一致性的不同子组估计值，但最近大地测量估计值的总体分散度仍保持在几毫米的水平，即接近年度地心运动本身的幅度。因此，协调季节性地心运动估计的努力仍然是必要的。与此同时，似乎可以安全地假设季节性地心运动模型，特别是目前用于卫星测高和卫星重力测量的模型，仍然不确定。