Estimation of a High-Accuracy Marine Geoid Offshore Newfoundland

Abstract. The scope of this paper is to investigate the possibility of improving the determination of the marine geoid using heterogeneous data. To achieve that, altimetry, shipborne gravity, bathymetry and quasi-stationary sea surface topography (QSST) data are implemented in the modeling procedure using spectral methods. Special attention is paid to the modeling and removal of high-frequency oceanic phenomena contaminating the geodetic mission (GM) altimetry sea surface heights (SSHs) through local crossover adjustment and low-pass filtering. For validation purposes, comparisons with a regional geoid model and T/P SSHs are performed, while the importance of crossover adjustment and low-pass filtering in removing part of the sea surface variability (SSV) is designated, especially for regions located is areas with high ocean dynamics. Furthermore, the results show that an altimetric geoid estimation accurate to about 7 cm (in terms of the standard deviation of the differences with T/P) is feasible, while the combination of altimetry and gravity data improves the gravimetric geoid determination by about 4- 5 cm. Additionally, it becomes evident that special care is needed for altimetric gravity field modeling, while conclusions on the appropriateness of the proposed altimetric and gravimetric data processing algorithms are drawn in an effort to derive a unified approach