Satellite altimetry and gravity field missions allow to determine with highest precision the sea surface as well as the geoid. The samll deviations between sea level and geoid (some ± 2m), the so called Dynamic Ocean Topography (DOT), is caused by surface circulations. Knowing the DOT it is possible to estimate mass and heat transport by assimilating the DOT into numerical models.
GEOTOP, a common DFG project of geodesists and oceanographers, aims to a more precise description of the absolute, time variable, three-dimensional velocity field and the determination of associated mass and heat transports. Thereby a circulation model is applied with a geodetic estimate of the dynamic ocean topography (DOT) being assimilated.
At DGFI an approach has been developed to determine the DOT directly along the ground tracks of altimeter satellites. In doing so identical filter are applied to geoid and sea surface heights. With the most recent GOCE gravity field models and multi-mission satellite altimetry meso-scale circulation pattern (Eddies) with spatial resolution down to 70 km become visible.