Acceleration signal in GRACE time-variable gravity in relation to interannual hydrological changes

P>We use 6 yr of data of the GRACE (Gravity Recovery and Climate Experiment) satellite mission, which yield estimation for interannual signals in gravity changes. We solve for such signals in the form of not only linear trend but also quadratic term (acceleration/deceleration) of mass variations globally at a spatial resolution of 500 km. On continents they signify hydrological mass transport, where any linear trend in precipitation minus evepotranspiration is the input to and hence responsible for, the quadratic change in continental water storage and hence in gravity. Comparison studies of geographical patterns of the quadratic (representing acceleration/deceleration) terms show interesting agreement of the hydrological model GLDAS with GRACE data in many major areas, providing independent assessment as to the quality and validity of the hydrological models for interannual applications.