Tuesday 23 August 2005

G2

PT0014
Current design of GOCE gravity gradient pre-processing
Bouman, Johannes¹
1 SRON National Institute For Space Research, The Netherlands
The gravity field mission GOCE is designed to greatly improve our knowledge of the static global gravity field in terms of a homogeneous, high accuracy and resolution. To this aim, GOCE will be the first satellite ever to measure in space gravity gradients by a technique called differential accelerometry. These gravity gradients are one of the key observations of GOCE from which the gravity field model, in terms of spherical harmonic coefficients, gridded geoid heights and gravity anomalies, will be derived. In order to reach this goal, the GOCE gravity gradients (GG) will be pre-processed. The first step is to correct for temporal gravity field variations. Secondly, outliers are detected and flagged. Finally, it is tried to remove any (systematic) measurement error possibly remaining in the observation data (this is referred to here as external calibration) and to assess the error model of the observations. The external calibration of the GG will be based on various data sources. Existing global gravity field information will be used, such as models derived from GRACE, but also terrestrial gravity data in selected regions as well as satellite-to-satellite tracking data from GOCE. The current envisaged design for the pre-processing of the GOCE gravity gradients will be reviewed with special emphasis on the combination of the different data sources for the external calibration.

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