

Simultaneous Improvement of Large Scale Geoid Height and Mean Sea Surface Topography
Verena Seufer^{(1)} , Manfred Wenzel^{(2)} , Jens SchrÃ¶ter^{(2)} , and ^{(3)}
^{(1)}
GeoForschungsZentrum Potsdam,
Telegrafenberg A6,
14473 Potsdam,
Germany
^{(2)} Alfred Wegener Institute, Bussestr. 24, Bremerhaven, Germany
^{(3)} , , ,
Abstract
In physical oceanography the slope of the large scale dynamic sea surface topography
can be used to calculate a surface geostrophic velocity as a reference for the general
circulation and its associated transports. The dynamic topography is the elevation of
the sea surface from the equipotential surface, i.e. it is identical with the difference
between the sea surface height as it is measured by satellite altimetry and the geoid
height. Therefore we calculate a mean dynamic topography (MDT) by combining altimetry and
gravity data.
A first guess MDT is calculated from a dynamical ocean model into which measurements of
temperature, salinity, property fluxes and sea surface height anomalies have been assimilated.
The large scales of this surface are subsequently improved by adding information about the
mean sea surface height from satellite altimetry and a 'satellite only' geoid model.
Simultaneously we estimate large scale corrections for the respectively used geoid models.
The combination takes into account full covariance matrices and considers the different error
structures of the three sources of data.
The results show that it is possible to use satellite altimetry not only for oceanographic
purposes but also to validate existing and new geoid models. Comparing the corrections of
different geoid models makes it possible to verify the improvement of 'satellite only' gravity
models by current satellite missions.
Workshop poster

