Optimal repeat cycles for gravity field satellite missions regarding ocean tide aliasing

Gravity field satellite missions observe mass variations on the Earth with cycles of several days. Compared to that ocean tides cause high frequent global mass variations. Therefore there is temporal aliasing of ocean tide model errors into the resulting mean gravity fields. These aliasing signals depend heavily on the repeat cycle. With respect to the ocean tides it is analyzed how an optimal repeat cycle could be determined. Compared to other mass variations on the Earth ocean tide signals contain discrete well known frequencies. For each satellite mission on a specific repeat cycle these frequencies are transformed to discrete alias frequencies, which can be computed analytically. Simulation results are derived from a spherical harmonic gravity field analysis from observations on synthetically generated orbit positions. Ocean tides are also modeled on these orbits. The effects on the estimation of a mean gravity field are analyzed. Furthermore possibilities to mitigate the ocean tide aliasing are discussed.