Comparison of signal/noise content in the combined monthly gravity fields and secular/seasonal
signal content in the deterministic signal model.
The deterministic GRACE signal model (bias, trend, annual and semi-anual variations)
is fitted to the monthly means of all GRACE time-series contributing to COST-G GRACE RL01 in the time period 2004-2010.
In the left plot the mean degree amplitudes of the differences between monthly gravity fields and a
static reference (GOCO05S, black line) are shown, either for the combined gravity fields (blue line),
or the signal model at the
mean epochs of each month (red line). The time-variable signal content in the low degrees is well represented
by the signal model, while in the medium to high degrees the differences between signal model and
combined gravity fields indicate the noise content of the combined solutions.
The right plot is based on monthly grids of either the combined gravity fields or the signal model
evaluated at the mean epochs of the months, both smoothed with a 400 km Gauss filter. It shows the
RMS of the differences to a static reference (GOCO05S) over the oceans.
spectral secular/periodic signal content
secular/periodic signal content over oceans
Below, monthly plots of the combined gravity fields and the deterministic GRACE signal model evaluated
at the corresponding epochs in either geoid heights or equivalent water heights are provided. All
plots are smoothed by a 400 km Gauss filter. As a static reference field GOCO05S was subtracted.