[G03-1] Current and future satellite gravity missions

[G03-1-03] Towards deriving temporal sampling requirements for future satellite gravimetry missions

^○David Wiese, Christopher McCullough (Jet Propulsion Laboratory, Pasadena, California, USA)

Studies have shown that future satellite gravimetry missions utilizing low-low satellite-to-satellite tracking (LL-SST) that have an improved onboard measurement system relative to the Gravity Recovery and Climate Experiment (GRACE) will be limited by temporal aliasing errors. The improved measurement system comes primarily in the form of improved electrostatic accelerometers to measure nonconservative forces as well as a laser interferometer to measure changes in distance between the satellites. Temporal aliasing errors are accumulated primarily because of deficiencies in models of high frequency mass variations (ocean tides, atmosphere and ocean mass variations), which are required in the first place because of the limited temporal sampling of a single pair of satellites. It has been shown that the impact of temporal aliasing errors on the gravity retrieval can be reduced substantially by implementing a mission architecture consisting of two pairs of satellites; however, even in this case the temporal aliasing errors remain as the dominant source of error. In this study, we make a first attempt to define temporal sampling requirements for future satellite gravimetry missions to go beyond the performance that two pairs of satellites can offer. We probe both the spatial and temporal characteristics of temporal aliasing errors to understand their impact on the gravity retrieval using numerical simulations. Through such studies, we can hypothesize as to what spatial and temporal scales of gravity field variations must be directly observed to gain specified improvements in accuracy and spatio-temporal resolution with which mass flux in the Earth system can be resolved.