Preliminary application of superconductive gravity technique on the investigation of viscosity at core-mantle boundary
超导重力技术在探讨核幔边界黏性特征中的初步应用

The retrograde rotational eigenmodes are produced due to the interaction between solid mantle and liquid core in a rotating elliptical Earth, it is usually called the free core nutation (FCN). The FCN quality factor (Q value), which depends on the viscosity at the core-mantle boundary (CMB), can effectively reflect the characteristics of the energy dissipation at the CMB. The viscosity of the CMB is estimated for the first time based on the FCN quality factor Q values determined from stacking 27 high-sampling and high-precision tidal gravity observations at 23 superconducting gravimeters stations in Global Geodynamics Project (GGP) network along the world. The numerical results show that the dynamic viscosity estimated at the CMB can reach at up to the order of 103 Pa·s, it is in good agreement with the nearest result obtained using VLBI observations by Canadian scientist Smylie. This result indicates also that the gravity is one of the effective techniques for investigating the deep internal structure of the Earth.