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Free keywords:
gravity field models, accuracy assessment, satellite crossover altimetry
DDC:
550 - Earth sciences
Abstract:
The new GFZ/GRGS gravity field models GRIM5-S1 and Cl, current initial models for the CHAMP mission, have been compared with other recent models (JGM 3, EGM 96) for radial accuracy (by means of latitude lumped coefficients) in computations on altimetry satellite orbits. The basis for accuracy judgements are extensive (multi-year) averages of crossover sea height differences from Geosat and ERS 1/2 missions. These data are fully independent of the data used to develop these gravity models. We tested how well these observed differences in all the world's oceans agree with projections of the same errors from the scaled covariance matrix of their harmonic geopotential coefficients. It was found that the tentative (model) scale factor of 5 for the formal standard deviations of the harmonic coefficients of the new GRIM fields is justified, i.e. the accuracy estimates, provided together with the geopotential coefficients, are realistic.
