The attempt to quantify the corrections of lunisolar nutation components was made after analysis of six sets of Earth’s orientation parameters (EOP). The deviations of the long-term nutation components about IAU2006/IAU2000A precession–nutation model are consistent with the uncertainties suggested by Mathews et al. (J Geophys Res Solid Earth, 2002. https://doi.org/10.1029/2001JB000390), but they exceed the errors determined in this work. The corrections are validated using the IERS 14C04 and IVS 19q4e combined solutions. After applying the corrections found in this work to the 14C04 nutation residuals, we analyzed the remaining signals, which contain the signature of the free core nutation (FCN). The eigenperiod of the FCN is fixed to the value derived from the resonance of the non-hydrostatic earth model in a priori. The amplitude of FCN is computed by fitting observations to the empirical model using a sliding window, the length of window is determined by taking into account the interference between those close nutation components and the FCN. In addition, we also fitted the nutation residuals by a viscous damping function; both methods produce the same results in the amplitudes of FCN. The magnitude of the free core nutation bears a “V-shape” distribution, and furthermore, the oscillation of the FCN shows a decay and a steady reinforcement before and after 1999. In order to examine the origin of the modulation in FCN’s magnitude, we briefly analyzed the possible damping or beating mechanism behind it. We diagnosed the magnitude and running phase changes of FCN by comparing it with the occurrence of the transient geomagnetic jerks. The weighted root mean square errors of nutation residuals are minimally reduced about \(36\%\) when the corrections to the 21 nutation components and the FCN signature are considered together.

在分析了六组地球方向参数（EOP）之后，尝试量化月季体章动成分的校正量。关于IAU2006 / IAU2000A进动-章动模型的长期章动成分的偏差与Mathews等人提出的不确定性是一致的。（J Geophys Res Solid Earth，2002。https：//doi.org/10.1029/2001JB000390），但它们超出了本文确定的错误。使用IERS 14C04和IVS 19q4e组合解决方案验证了更正。在对14C04章动残差进行这项工作中发现的校正后，我们分析了其余信号，其中包含自由核心章动（FCN）的签名。FCN的本征周期固定为先验地从非静水地球模型的共振得出的值。FCN的幅度是通过使用滑动窗口将观测值拟合到经验模型来计算的，窗口的长度是通过考虑这些紧密章动分量与FCN之间的干扰来确定的。另外，我们还通过粘性阻尼功能拟合了章动残差。两种方法在FCN振幅上产生相同的结果。自由核心章动的大小呈“ V形”分布，此外，FCN的振荡在1999年之前和之后显示出衰减和稳定的增强。为了检验FCN大小的调制起源，我们简要分析了其背后可能的阻尼或跳动机制。我们通过将FCN的大小和运行相位变化与瞬态地磁跳动的发生进行比较来进行诊断。如果同时考虑对21种章动成分和FCN签名的更正，则为\（36％）。