Ocean bottom pressure observation off Sanriku and comparison with ocean tide models Altimetry and barotropic signals from ocean models

We discuss tidal and non-tidal signals which are obtained from ocean bottom pressure (OBP) measurements at two sites off Sanriku, Japan. Comparison between the observed tidal component and five ocean tide models shows that recent models have accuracy better than 1.3 cm in terms of root sum square of vector differences for eight principal constituents. The empirical estimates of non-tidal signal from TOPEX/POSEIDON (T/P) and JASON-1 deviate from barotropic signals observed by OBP recorders, which can be attributed to baroclinic component in the altimeter data. We also compared the non-tidal barotropic signal derived from the observation with those from ECCO model (wind-driven) and Kyushu University model (pressure-driven). The comparison indicates that the pressure-driven model increases explained variance and it is suggested to combine the wind-driven model and the pressure-driven model in order to describe non-tidal ocean mass variability in particular at period shorter than 30 days.