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Abstract:
Recently completed performance studies of future gravity mission concepts arrived at sometimes contradicting
conclusions about the importance of non-tidal aliasing errors that remain in the finally retrieved gravity field
time-series. In those studies, typically a fraction of the differences between two different models of atmosphere
and ocean mass variability determined the magnitude of the aliasing errors.
Since differences among arbitrary pairs of the numerical models available might lead to widely different
aliasing errors and thus conclusions regarding limiting error contributors of a candidate mission, we present here
for the first time a version of a realistically perturbed de-aliasing model that is consistent with the updated ESA
Earth System Model for gravity mission simulation studies (Dobslaw et al., 2015). The error model is available
over the whole 12-year period of the ESA ESM and consists of two parts: (i) a component containing signals from
physical processes that are intentionally omitted from de-aliasing models, as for a example, variations in global
eustatic sea-level; and (ii) a series of true errors that consist of in total five different components with realistically
re-scaled variability at both small and large spatial scales for different frequency bands ranging from sub-daily to
sub-monthly periods.
Based on a multi-model ensemble of atmosphere and ocean mass variability available to us for the year
2006, we will demonstrate that our re-scaled true errors have plausible magnitudes and correlation characteristics
in all frequency bands considered. The realism of the selected scaling coefficients for periods between 1 and
30 days is tested further by means of a variance component estimation based on the constrained daily GRACE
solution series ITSG-GRACE2014. Initial full-scale simulation experiments are used to re-assess the relative
importance of non-tidal de-aliasing errors for the GRACE-FO mission, which might be subsequently expanded to
further mission candidates currently under consideration for a potential Next Generation Gravity Mission.
Dobslaw, H. Bergmann-Wolf, I., Dill, R., Forootan, E., Klemann, V., Kusche, J., Sasgen, I. (2015), The
updated ESA Earth System Model for future gravity mission simulation studies, J. Geodesy, doi:10.1007/s00190-
014-0787-8.
