Validation of global ocean tide models using the superconducting gravimeter data at Syowa Station, Antarctica, and in situ tide gauge and bottom-pressure observations

We performed a validation study of six ocean tide models (CSR4.0, GOT99.2b, NAO.99b, FES2004, TPXO7.1, and TPXO7.2) using superconducting gravity data recorded at Syowa Station. From comparison with the observed loading effects, the most optimum ocean tide model was found to be TPXO7.2, which had a combined root-mean-square (RMS) misfit of 0.194 μGal for the eight major (four diurnal and four semidiurnal) waves. The next best ocean tide model was NAO.99b, with a combined misfit of 0.277 μGal. To determine the effect of inclusion of regional tide gauge and bottom-pressure data around Syowa Station, we estimated the combined RMS error for all eight waves; incorporation of these regional data into the TPXO7.2 model resulted in a 5% reduction in the misfit. Our phase lag anomalies indicate that the scatter of the out-phase component was greater than that of the in-phase component in the final residuals; this tendency was especially clear for O1, K1 and M2 waves. Improvement of the phase differences was the key to determine the optimum ocean tide model.