LAUSR

Abstract Geophysical excitations of length-of-day (LOD) variations is of great significance in understanding changes in the Earth's spin rate and interactions between geophysical fluids and the solid Earth, as well as validating the reliability of atmospheric, oceanic and hydrological models. In this study seasonal excitations of LOD variation during 06.30,1987–06.30,2017 are investigated using both harmonic and inharmonic analyses. We examined the agreements between the IERS EOP 14 C04 ΔLOD series and that from the previous version EOP08C04, and analyzed contributions of atmospheric, oceanic, hydrological and sea level angular momenta to seasonal excitations of LOD variations on the bases of the ESMGFZ products. We found that the sea level angular momentum plays an important role in global mass conservation and can bring better agreements between the geophysical and geodetic excitations.