GOCE gradiometer validation in satellite track cross-overs

Abstract

Besides external validation methods using auxiliary data, internal integrity checks will be an important technique to assure the full functionality of the GOCE gravity gradiometer. In this paper, cross-over validation is presented to verify and to supplement other validation procedures such as interpolation methods along the orbit. The prospects of cross-over validation are discussed. Cross-over validation, as a relative approach, is capable to detect gross errors, data gaps and long term drift parameters to some extent, whereas geographically fixed error phenomena and constant biases remain undiscovered. Adequate reduction procedures to deal with altitude and attitude differences have been developed and applied. Simulated gravity gradiometry data sets with different artificial errors are processed. Combining data from different epochs, drift behaviour and short-term biases are very well identified through cross-over validation. Single gross errors and jumps might better be detected by continuous interpolation methods, depending on their temporal extent. Cross-over validation offers a fast approach to assess the quality of space gradiometry independently with almost global coverage.