Empirical modeling and analysis of ocean tides

The almost twenty years long time series of precise and nearly global altimeter measurements of missions with the different sampling characteristics allow a very percise emperical modeling of ocean tides (cf. the already published models EOT08a, EOT10 and EOT11a). These models describe not only tidal elevations which with the corresponding currents are generally important for the coast protection of the coastal ecosystem. Ocean tides cause the energy conversion into the heat and short period mass redistribution in the system Earth. The tidal effects have to be corrected or modeled for the geodetic space techniques: e.g. the geometric effect on the altimetric surface heights, gravitational effects on the GRACE and GOCE gravity fields, effects on the Earth rotation, and the loading effects for the precise point positioning.

: Residual amplitudes (cm) of the partial tide M2 inside the model EOT10a in relation to the reference model FES2004. In the middle: global spreading; outside: amplitudes of the Yellow Ocean (left), the North Sea (above) and over the Patagonial Shelf (below).

The accuracy and resolution of the ocean tide models will be increased by the analysis of the additional novel and improved data (of CryoSat-2, SARAL/Altika, Sentinel-3). The longer and more accurate time series allow estimating the tidal constituents with smaller amplitudes. Measurements of partially ice-covered regions of the ocean need a special consideration. The weakness of the altimetry for the polar oceans should be overcome through a combined analysis of GRACE and altimetry. All new tide models have to be carefully validated. For these purposes the data of coastle tide gauges and shallow water bottom pressure sensors, statistics of the crossover differences at altimeter ground tracks, loading tides from GNSS time series come into consideration. The new ocean models have to be compared with the independent global and regional ocean tide models. The consideration of gravitational effect of ocean tides onto satellite orbits and gravity fields sensors requires the spherical harmonic representation of oecan tide tables.