Sea surface topography, bathymetry and marine gravity field modelling

The mapping phases of altimetric satellites (Geodetic Missions) offer a vast amount of sea surface height data and provide high-accuracy and high-resolution gravity field information. In this thesis, altimetry-derived gravity anomalies were used in a least squares collocation (LSC) method to improve the estimation of the bottom ocean topography and its gravimetric response. Two- and three-layer models were developed and combined solutions with shipborne depth soundings were implemented. Compared to global bathymetry models, the newly derived ones manage to provide smoother data by 15–25% when taken into account through a residual terrain modeling (RTM) reduction in a remove-compute-restore procedure for gravity field modeling.; Altimetric sea surface heights (SSHs) were also used in this thesis for geoid and gravity field determination taking into account the quasi-stationary sea surface topography (QSST) and bathymetry signals. Special attention was paid to the modeling of the high-frequency sea surface variability (SSV) signal, which contaminates the altimetric measurements. The results show that the accuracies of the altimetric geoid and gravity field is at the 5 cm and 8 mGal level (1σ), respectively, compared to TIP SSHs. Additionally, gravimetric and combined geoid solutions using the input output system theory (IOST) were developed showing that the combined use of shipborne and multi-satellite altimetry data improve the gravimetric geoid estimation by 2 to 8 cm (1σ). Finally, QSST and geostrophic flow estimates were derived, indicating that there is possibly remaining QSST signal above harmonic degree 20 thus illustrating the importance of geodetic methods in oceanographic studies.