Seasonal deformation related to mass redistribution on the Earth’s surface can be recorded by continuous global navigation satellite system (GNSS) and simulated by surface loading models. It has been reported that obvious discrepancies exist in the seasonal deformation between GNSS estimates and modeled loading displacements, especially in the horizontal components. The three-dimensional seasonal deformation of 900 GNSS stations derived from the International GNSS Service (IGS) second reprocessing are compared with those obtained from geophysical loading models. The reduction ratio of the weighted mean amplitude of GNSS seasonal signals induced by loading deformation correction is adopted to evaluate the consistency of seasonal deformation between them. Results demonstrate that about 43% of GNSS-derived vertical annual deformation can be explained by the loading models, while in the horizontal components, it is less than 20%. To explore the remaining GNSS seasonal variations unexplained by loading models, the potential contributions from Inter-AC disagreement, GNSS draconitic errors, regional/local-scale loading and loading model errors are investigated also using the reduction ratio metric. Comparison of GNSS annual signals between each IGS analysis center (AC) and the IGS combined solutions indicate that more than 25% (horizontal) and 10% (vertical) of the annual discrepancies between GNSS and loading models can be attributed to Inter-AC disagreement caused by different data processing software implementations and/or choices of the analysis strategies. Removing the draconitic errors shows an improvement of about ~ 3% in the annual vertical reduction ratio for the stations with more than fifteen years observations. Moreover, significant horizontal discrepancies between GNSS and loading models are found for the stations located in Continental Europe, which may be dominated by the regional/local-scale loading. The loading model errors can explain at least 6% of the remaining GNSS annual variations in the East and Up components. It has been verified that the contribution of thermoelastic deformation to the GNSS seasonal variations is about 9% and 7% for the horizontal and vertical directions, respectively. Apart from these contributors, there are still ~ 50% (horizontal) and ~ 30% (vertical) of the GNSS annual variations that need to be explained.

与地球表面质量重新分布相关的季节性变形可以通过连续全球导航卫星系统（GNSS）记录并通过表面载荷模型进行模拟。据报道，GNSS 估计值和模拟加载位移之间的季节性变形存在明显差异，尤其是在水平分量中。将来自国际 GNSS 服务 (IGS) 二次后处理的 900 个 GNSS 站的三维季节性变形与从地球物理载荷模型中获得的进行了比较。采用加载变形校正引起的GNSS季节信号加权平均振幅的折减率来评价它们之间季节变形的一致性。结果表明，大约 43% 的 GNSS 衍生的垂直年变形可以通过加载模型来解释，而在水平分量中，这一比例不到 20%。为了探索加载模型无法解释的剩余 GNSS 季节性变化，还使用缩减比度量研究了来自 AC 间分歧、GNSS draconitic 误差、区域/局部尺度加载和加载模型误差的潜在贡献。每个 IGS 分析中心 (AC) 和 IGS 组合解决方案之间的 GNSS 年度信号比较表明，超过 25%（水平）和 10%（垂直）的 GNSS 和加载模型之间的年度差异可归因于 AC 间的分歧由不同的数据处理软件实现和/或分析策略的选择引起。去除 draconitic 误差表明，观测超过 15 年的台站的年垂直缩减率提高了约 3%。此外，对于位于欧洲大陆的站，发现 GNSS 和加载模型之间存在显着的水平差异，这可能由区域/局部尺度的加载主导。加载模型误差至少可以解释东部和向上分量剩余 GNSS 年度变化的 6%。经验证，热弹性变形对 GNSS 季节变化的贡献在水平和垂直方向上分别约为 9% 和 7%。除了这些贡献者之外，仍有约 50%（水平）和约 30%（垂直）的 GNSS 年度变化需要解释。