Global Evaluation of New GRACE Mascon Products for Hydrologic Applications

International audienceRecent developments in mascon (mass concentration) solutions for GRACE (Gravity Recovery andClimate Experiment) satellite data have significantly increased the spatial localization and amplitude ofrecovered terrestrial Total Water Storage anomalies (TWSA); however, land hydrology applications havebeen limited. Here we compare TWSA from Apr. 2002 through Mar. 2015 from (1) newly releasedGRACE mascons from the Center for Space Research (CSR‐M) with (2) NASA JPL mascons (JPL‐M), andwith (3) CSR Tellus gridded spherical harmonics rescaled (sf) (CSRT‐GSH.sf) in 176 river basins, ~60% ofthe global land area. Time series in TWSA mascons (CSR‐M and JPL‐M) and spherical harmonics arehighly correlated (mostly >0.9). The signal from long‐term trends (up to ±20 mm/yr) is much less thanthat from seasonal amplitudes (up to 250 mm). Net long‐term trends, summed over all 176 basins, aresimilar for CSR and JPL mascons (66–69 km3/yr) but are lower for spherical harmonics (~14 km3/yr).Long‐term TWSA declines are found mostly in irrigated basins (‐ 41 to ‐69 km3/yr). Seasonal amplitudesagree among GRACE solutions, increasing confidence in GRACE‐based seasonal fluctuations. Rescalingspherical harmonics significantly increases agreement with mascons for seasonal fluctuations, but lessfor long‐term trends. Mascons provide advantages relative to spherical harmonics, including (1) reducedleakage from land to ocean increasing signal amplitude, and (2) application of geophysical dataconstraints during processing with little empirical post‐processing requirements, making it easier fornon‐geodetic users. Results of this product intercomparisonshould allow hydrologists to better select suitable GRACE solutions for hydrologic applications