Abstract:

Tidal aliasing issues involving the GRACE gravity solutions are reviewed. The most problematic tides for monthly gravity solutions are K2 and S2, whose errors induce false signals at alias periods of 3.7 years and 161 days, respectively. In addition, for tidal analysis of GRACE data, K1 is problematic, because only two phase angles are well sampled until several years into the mission. We show preliminary tidal solutions from GRACE range-rate data of M2 and O1 tides. These solutions indicate errors in present models primarily in polar seas, as expected.