Satellite characterization of water mass exchange between ocean and continents at interannual to decadal timescales

Since 2002, GRACE provides estimates of the transfers of water-mass from land to the ocean. However, these estimates are uncertain as they show discrepancies when different approaches and different parameters are used to process the GRACE data. I revisit the treatment of GRACE data, paying a special attention to the different sources of errors and uncertainties. The main sources of uncertainty in the global water budget, at annual to interannual time scales, are the spread in the geocenter corrections and the uncertainty in the GIA correction. This is particularly true for the ocean mass and glacier and TWS mass change estimates for which the uncertainty in trends for the period from 2005 to 2015 is ±0.33mmSLE/yr.