Comparison of signal/noise content in the combined monthly gravity fields and secular/seasonal signal content in the deterministic signal model.

The deterministic GRACE-FO signal model (bias, trend, annual and semi-anual variations) is fitted to the monthly means of all GRACE-FO time-series contributing to the RL02 combination. In the left plot the mean degree amplitudes of the differences between monthly gravity fields and a static reference (GOCO06S, 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 bottom plots are 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. They show the RMS of the differences to a static reference (GOCO06S) over the oceans.

geoid height
equivalent water height
spectral secular/periodic signal content spectral secular/periodic signal content spectral secular/periodic signal content
secular/periodic signal content over oceans secular/periodic signal content over oceans secular/periodic signal content over oceans

Below, monthly plots of the combined gravity fields and the deterministic GRACE-FO 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 GOCO06S was subtracted.

month
COMB (geoid)
model (geoid)
COMB (EWH)
model (EWH)
08/2024
COMB:
Model:
COMB:
Model:
09/2024
COMB:
Model:
COMB:
Model:
10/2024
COMB:
Model:
COMB:
Model:
11/2024
COMB:
Model:
COMB:
Model:
12/2024
COMB:
Model:
COMB:
Model:
01/2025
COMB:
Model:
COMB:
Model:
02/2025
COMB:
Model:
COMB:
Model:
03/2025
COMB:
Model:
COMB:
Model: