Impact of short period, non-tidal, temporal mass variability on GRACE gravity estimates

Using orbital simulations of the Gravity Recovery and Climate Experiment (GRACE) spacecraft, we examined the effects on gravity recovery due to short period, non-tidal temporal mass variability in the atmosphere, ocean, and continental hydrology. We found that the magnitude of the aliasing error was strongly correlated with the power of the high-frequency variability of the models. Degree error relative to measurement error increased by a factor of similar to20 due to atmospheric aliasing (corresponding to geoid anomalies of approximately 1 mm at 500 km wavelengths), by a factor of similar to10 due to the ocean model, and by a factor of similar to3 due to the continental hydrology model. De-aliasing done with approximate models gave the greatest reduction in aliasing error for the mid-degrees and higher. For the atmosphere, the residual error was similar to1/5 times that of the aliasing error. A barotropic ocean model reduced the aliasing error due to a baroclinic model to nearly the level of measurement noise.