Quantifying GRACE data contamination effects on hydrological analysis in the Murray-Darling Basin, southeast Australia

This paper investigates and quantifies the near-field and far-field contamination effects from Groupe de Recherche en Geodesie Spatiale GRACE products to assess whether or not they influence the accuracy with which hydrological signals in the Murray-Darling Basin, southeast Australia can be estimated. Far-field contamination was assessed by simulating some of the world's largest geophysical processes which generate major gravitational signals (e.g. melting of the Greenland icesheet, hydrology in the Amazon Basin) and measuring the proportion of the simulated signal detected in the Murray-Darling Basin. Near-field contamination from the Australian continent (excluding the Murray-Darling Basin) was also assessed. The sum of the near-field and far-field effects revealed a maximum of 10 mm (equivalent water height) of spurious signal within the Murray-Darling Basin. This equates to only one quarter of the formal uncertainty of the basin-scale estimates of changes in total water storage. Thus, GRACE products can be used to monitor broad-scale hydrological trends and variability in the Murray-Darling Basin without the need to account for contamination from external geophysical sources.