Designing Earth Gravity Field Missions for the Future: A Case Study
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Gravity field changes due to mass changes in the Earth system have been observed successfully by the GRACE mission. Having a single tandem like GRACE limits the achievable resolution of observing such mass changes both in time and space. A simulation study was carried out to make a first assessment of the impact of different gravity satellite formations on the retrieval of temporal gravity, in this case caused by hydrology. These formations include polar formations of one, two and four GRACE-type tandems and a formation that includes one polar and one non-polar tandem. A comprehensive force modeling was used including gravity field changes due to ocean tides and hydrological, atmospheric, oceanographic, solid-earth and ice mass change processes. The impact of errors in these models in conjunction with observation errors by the space-borne gravity instruments was assessed. First results indicate that having more than one tandem helps to reduce the impact of errors in background models such as ocean tides, provided that instrument observation errors are sufficiently low.
KeywordsSpace-borne gravimetry Future missions Low–low satellite-to-satellite tracking Observation errors Model errors Satellite formations
ESA provided the funding for a large part of the research described in this paper. An important part of the computations and simulations were done with the GEODYN software, kindly provided by NASA/GSFC, Greenbelt, Maryland.
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