[G03-5] Solid-Earth and other applications

[G03-5-03] Ocean tide alias spectrum estimation for satellite gravity missions

^○Wei Liu, Nico Sneeuw (University of Stuttgart, Stuttgart, Germany)

Spaceborne gravimetry missions like GRACE suffer from ocean tide alias errors which can be understood into two steps: undersampling of the ocean tides from satellite orbit and recombination of the satellite measurements over time and space while recovering the gravity field. Although ocean tide models are used for de-aliasing during the gravity field retrieval, the uncertainty in those models will directly alias into the recovered gravity field. If the aliasing frequencies of each tidal constituent would be known, ocean tide alias errors can be mitigated in a post-processing mode. Hence, it is crucial to evaluate the alias periods with respect to the type of satellite mission and to field recovery strategy. Here we develop an approach to estimate the alias spectrum of ocean tide errors based on the abovementioned two steps, taking both satellite orbit sampling and recovery process into consideration. Apart from a GRACE-type single-pair mission, the alias spectrum of a so-called Bender formation is investigated. The latter double pair formation is considered to be the most promising type for future gravity missions and deserves a closer look.