A Quantitative Analysis of the Contributions of High-Low Satellite-to-Satellite Tracking (SST) Observations used for Gravity Field Estimation

Satellite gravimetry missions continue to provide data to produce high resolution gravity models of the Earth for over 20 years. The Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) exemplifies the current state-of-the-art mission architecture. GRACE-FO consists of a pair of twin satellites flying in the same orbit with an onboard laser ranging interferometer (LRI) system and GNSS receivers. The LRI is used for accurately tracking low-low satellite range change. The GNSS receivers are used for high-low SST to GNSS satellites, contributing information for satellite positioning, timing, and long-wavelength gravity field information. We present results from a numerical simulation study to characterize the contributions of various high low SST observation architectures relative to the GRACE-FO configuration. These include gravity fields estimated with only high-low SST observations as well as fields with combined high-low and low-low SST observations. Other aspects of the setup such as measurement observables, bias parameterization, and noise characteristics are evaluated to better understand how high-low SST and its errors impact gravity field estimation. We anticipate the results to be useful in the architecture and science data analysis algorithms for future mass change missions.