Impact of space-borne gravity gradiometer instrument filter on observation error and gravity field recovery performance for GOCE
The primary instrument on board of the future ESA gravity field observing satellite GOCE is a gravity gradiometer. The observations from this instrument will be passed through a 7th-order Butterworth filter in order to reduce high-frequency noise and aliasing due to the output rate of 1 Hz. This filtering will distort the gravity gradients that are to be measured, which can however be largely compensated by a time tag correction. An assessment has been made of the remaining observation error after this correction and its impact on gravity field recovery performance. It has been found that the filtering leads to a very small increase of the gravity field recovery error budget at the medium to short wavelengths after application of the optimal time tag correction. Only at the very long wavelengths a slight degradation might take place. However, it is anticipated that the GOCE gravity field recovery will be improved/dominated by GPS satellite-to-satellite tracking observations at these long wavelengths.
Key wordsspace-borne gravity gradiometer Butterworth filter time tag correction gravity field recovery performance
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