Long‐period tidal factors at Antarctica Syowa Station determined from 10 years of superconducting gravimeter data

Abstract

We determined long‐period gravimetric tidal parameters from 10 years of superconducting gravimeter observations at Syowa Station in Antarctica. The obtained amplitude and phase lead for the Mm wave were 6.106 ± 0.030 μGal (μGal = 10 −8 m s −2 ), 0.32° ± 0.28°, respectively, and those for the Mf wave were 11.657 ± 0.018 μGal, 0.78° ± 0.09°, respectively. We also determined the parameters of other tidal constituents with periods of 6 to 32 days; Mqm, Msqm, Mtm, Mstm, Msf, Msm, and their frequency dependence was estimated by means of a weighted least squares method. The observed values, corrected by the four ocean tide models of Schwiderski, NAO.99L, FES99, and TPXO6.0, were compared with the theoretical values calculated from the elastic and inelastic solid Earth tide models by Dehant et al. Even though the values of the ocean tide corrections have relatively large discrepancies between the four models and it is still difficult to discuss the degree of inelasticity of the Earth for this frequency band, we can say that the observations favor the inelastic Earth model rather than the elastic model.