EOT08a - a new global ocean tide model
Caused by the attraction of Moon and Sun the ocean tides are the strongest, short-period water mass redistribution in the Earth system. Ocean tides have to be known with high precision if e.g. gravity field variations observed by GRACE are used to derive water mass redistribution of the continental hydrology known to be the most uncertain subsystem of the global water cycle.
An empirical analysis of nearly 15 years of harmonized and cross-calibrated multi-mission altimetry data now succeeded to generate a new global ocean tide model, EOT08a (Savcenko & Bosch, 2008). The model provides amplitudes and phases for major diurnal and semi-diurnal constituents (K1, O1, Q1, M2, N2, S2, K2, 2N2) and the non-linear M4 tide on a dense 7.5'x7.5' geographical grid. Compared to the FES2004 reference model EOT08a identifies residual amplitudes of up to 15 cm in shallow water like the Yellow Sea (Fig. 1). In open ocean there are extended areas with residual amplitudes of 1 - 2 cm (Fig. 2).