Spectral analysis of residual GRACE and GRACE-FO range accelerations

Abstract

GRACE and GRACE-FO K-band range-rate post-fit residuals obtained after a common estimation of monthly gravity field coefficients and ancillary satellite parameters represent a complex superposition of different effects. In this contribution, we analyze the component of the residuals that is related to geophysical effects. We low pass filter and differentiate range-rate post-fit residuals to obtain residual range-accelerations. A spectral analysis of globaly gridded residual range-accelerations reveals unmodeled signal related to (ocean) tides and hydrology. The time series with approximately 100 millions of data records allows us to identify main periodic contributors in different bands. Diurnal and semi-diurnal signal can be resolved on a 5x5 degree grid, while periods of 5 and 3 hours can be resolved on a 7.5x7.5 and 10x10 degree grid.