Validation of the GOCE Time-Wise Gravity Field Models Via the Estimation of the Ocean's Mean Dynamic Topography
Brockmann, Jan Martin; Becker, Silvia; Schuh, Wolf-Dieter
Institute of Geodesy and Geoinformation, University of Bonn, GERMANY
The determination of the mean dynamic topography as the difference between the mean sea surface and the geoid is not straightforward because of different spatial resolutions of altimetric measurements and satellite based gravity field models. The quality of the estimated mean dynamic topography from an altimetric mean sea surface and a gravity field model mainly depends on the spatial resolution and the accuracy of the particular gravity field model. We developed an integrated approach to estimate directly the mean dynamic topography and its covariance matrix or its normal equations respectively. No special filter techniques or smoothness conditions are explicitly applied to the mean dynamic topography within this approach. Consequently, the quality and accuracy of the estimated dynamic topography reflects the quality and accuracy of the integrated gravity field model. We will present the achieved results over the North Atlantic Ocean based on observations of Jason-1 and Envisat and GOCE time-wise gravity field models. Meanwhile four releases of GOCE Earth's gravity field models are available. Thus, four estimates of the local mean dynamic topography are computed. The different models and their corresponding full variance/covariance matrices will be analyzed. Within this study we demonstrate the progress done in GOCE processing and demonstrate the valuable contribution of the new (pure) GOCE gravity field models in the context of estimating geodetic mean dynamic topography models.