Advance in prediction of body tide and ocean tidal loading

Earth’s body tide is the largest periodic perturbation in the solid Earth. We developed a new computer program ‘K2-Tide’, which predicts body tide accurately and efficiently for any place on the globe. K2-Tide has outgrown its former version K-Tide and JTIDAL, and its algorithm includes corrections for the permanent tide and the coupling between Earth’s spin and tidal deformation–those neglected in the two former ones. Other enhancements are the updated physical constants and compensation of mantle inelasticity. For any specified location and time span in the 21 st century, K2-Tide computes tidally induced perturbations; surface displacement, gravity change, tidal potential and deviation of the vertical. Periodic changes of ocean water height associated with the ocean tides induce secondary deformation in the crust–ocean tidal loading (OTL). By using NAO.99 ocean tide model and the IASPEI Earth model, we constructed ‘K-OTL’, which similarly predicts OTL displacement and gravity changes (originally designed to be used in Korea). Twelve tidal constituents considered in K-OTL are M 2 , S2, K 2 , N 2 , O 1 , K 1 , P 1 , Q 1 , M f , M m , S sa , and S a . Amplitudes of 1 cm and 3 μGal are typical values of OTL deformation in major urban area of Korea. These OTL displacement and gravity show strong semidiurnal variation and become smaller at the eastern parts of Korea. As the amplitude and phase of ocean tide largely vary at different regions on the globe, so do the OTL effects.