COST-G quality control: global plots of monthly anomalies in water heights

Global plots of monthly anomalies in equivalent water heights

Monthly anomalies are derived by subtraction of a deterministic signal model (bias, trend, annual and semi-annual variations) from the monthly solutions. The signal model is fitted to the monthly means of all time-series in the time period 2004-2010, and extrapolated to earlier or later epochs to avoid poor quality solutions in the early or late phase of the GRACE mission to impact the signal model (each month is weighted equally).

For each spherical harmonic coefficient an individual model is fitted, the signal model is evaluated at the middle epochs of the monthly solutions and then the spherical harmonic coefficients are expanded into global grids, applying a 400 km Gauss filter.

Anomalies over continents are mainly due to non-periodic hydrological signals or non-linear mass trends in polar regions. These should be consistent in all time-series. Anomalies over the oceans are dominated by noise and allow for a rough noise assessment of the different time-series.

month

AIUBp

APM

CSR6

GFZ6

GRGS

HUST2

ITSG

JPL

SUS2

SWPU

Tongji