New methods for linking science objectives to mission architectures: A case study comparing single and dual-pair satellite gravimetry mission architectures

The expected performance of satellite gravimetry mission architectures is typically assessed in the context of degree variance plots, where errors are measured spectrally, per spherical harmonic degree. While this analysis can be insightful in many respects, it lacks depth in many practical aspects. Science objectives for measuring mass change within the Earth system are typically expressed in terms of a desired spatial resolution, temporal resolution, and accuracy rather than in terms of spherical harmonic degrees of a gravity field. Further, current satellite gravimetry missions (GRACE and GRACE-FO) rely heavily on post-processing methods to remove correlated errors in the gravity field and reduce errors at short wavelengths; the effectiveness of these methods is difficult to assess in the spectral domain. Here, we present a framework for simultaneously assessing the expected accuracy of satellite gravimetry mission architectures over a range of spatial (200 - 1800 km) and temporal (1-30 day) scales. This framework provides a direct link between science objectives and mission architectures which allows for the inclusion of preferred post-processing methods in a straight forward manner. The performance of dual-pair mission architectures versus single-pair mission architectures are assessed as a case study.