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Simultaneous Improvement of Large Scale Geoid Height and Mean Sea Surface Topography

Verena Seufer(1) , Manfred Wenzel(2) , Jens Schröter(2) , and  (3)

(1) GeoForschungsZentrum Potsdam, Telegrafenberg A6, 14473 Potsdam, Germany
(2) Alfred Wegener Institute, Bussestr. 24, Bremerhaven, Germany
(3) , , ,


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


                 Last modified: 07.10.03