Investigation of the Earth's nearly diurnal free wobble resonance using tidal gravity observations with superconducting gravimeters

The dynamic effects of a liquid core within an elastic mantle, confined by an elastic elliptical boundary, will lead to another Earth's rotating eigen mode besides Chandler's wobble, called nearly diurnal free wobble (NDFW) wi th a period about one day. In this paper, the theoretical bacground of NDFW and its resonance on diurnal tesseral gravity tides is introduced briefly. The tidal gravity observations with superconducting gravimeters at station s of Wuhan and Brussels are stacked to investigates NDFW. The NDFW-resonanc e on the four tidal waves K-1, P-1, psi(1) and Phi(1) is modeled to determi ne the resonant parameters. The final eigenfreqency and the quality factor are obtained for NDFW.