Test Results for Analysing Altimeter Data by a Quasi-Geostrophic Model of the Sea Surface Topography
A method is outlined for analysing altimeter data in order to improve the geoid over the oceans. It assumes that the height of the sea surface above a reference ellipsoid, derived from the altimetric measurement by an orbit computation, consists of the geoid undulations, the height of the sea surface above the geoid and the radial component of the orbital error. The height of the sea surface above the geoid is expressed by modelling the oceanic currents. To keep the computational burden for such an approach manageable, a quasi-geostrophic model with two layers is chosen, and the area of the analysis of the data is restricted to a region of an ocean. The orbital errors are determined by a crossing point analysis, and knowledge on the geoid from satellite tracking and surface gravity data is introduced as prior information for a Bayesian estimation. It leads to a modified Kalman filter for the simultaneous estimation of all parameters. Test results for computing the sea surface topography with respect to the geoid by means of the quasi-geostrophic model are presented.
KeywordsWind Stress Automatic Gain Control Altimeter Data Orbital Error Reference Ellipsoid
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