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Ocean Surface Topography from Space
Impact of GOCE on MDT determination


Alexander Horvath - (Technical University Munich, Institute of Astronomical and Physical Geodesy (IAPG))

  Roland Pail
Thomas Gruber
(Technical University Munich, Institute of Astronomical and Physical Geodesy (IAPG))
(Technical University Munich, Institute of Astronomical and Physical Geodesy (IAPG))

Impact of GOCE on MDT determination
Error of an Anisotropic filtered MDT (100 iterations) in the Drake Passage on a 30min grid in meters

The main objective of this project is to determine and quantify the impact of the newly generated geoid field solutions from the GOCE mission on the estimation of a mean dynamic topography.

Knowledge of the overall error budget and accuracy of a Mean Dynamic Topography and subsequently derived Geostrophic Velocities is important information for ocean studies.

Following the basic Equation MDT = MSS - N with the Mean Dynamic Topography (MDT), a Mean Sea Surface (MSS) and the Geoid Height (N), one can clearly see that the MDT is composed of two entities derived from different measurement types and hence different error budgets. They can be considered as uncorrelated as they are in our case derived by different and independent techniques. The Error Budget of the MDT has therefore two contributions, the Geoid error and the MSS error. They both simply sum up to the overall MDT error.

The investigations are based on the statistical analysis of the full covariance information provided from a GOCE geoid and the error information from a MSS. The core part of the analysis represents the stochastic modeling of the MDT and the geostrophic velocities derived from it, and therefore the propagation of the variance-covariance information to MDT and velocity error estimates. Attention will be drawn to the effects of the filtering applied to the MSS and geoid heights in order to ensure spectral consistency between the two entities on both, the MDT product, and the corresponding propagated error estimates.

This analysis will allow quantifying the respective contributions of the two MDT ingredients to the overall MDT error and its derivatives like geostrophic velocities.

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