Assessment of GRACE temporal signature over the upper Zambezi

The temporal signature of terrestrial storage changes inferred from the Gravity Recovery And Climate Experiment (GRACE) has been assessed by comparison with outputs from a calibrated hydrological model of the upper Zambezi and surroundings and an inspection of the within-month ground track coverage of GRACE together with spatio-temporal rainfall patterns. The comparison of the hydrological model with GRACE reveals temporal inconsistencies between both datasets. Because the LEW model has been calibrated and validated with independent data sources, we believe that this is a GRACE artifact. The within-month ground track coverage shows an irregular orbit behaviour which may well cause aliasing in the GRACE monthly deconvolutions. This aliasing thus may cause temporal inconsistencies between GRACE
and other datasets.