Global evaluation of new GRACE mascon products for hydrologic applications. Issue 12 (17th December 2016)

• Record Type: Journal Article
• Authors: Scanlon, Bridget R.; Zhang, Zizhan; Save, Himanshu; Wiese, David N.; Landerer, Felix W.; Long, Di; Longuevergne, Laurent; Chen, Jianli
• Is Part Of: Water resources research. Volume 52:Issue 12(2016:Dec.)
• Page Start: 9412
• Page End: 9429
• Publication Date: 2016-12-17
• Subjects: remote sensing -- GRACE satellites -- terrestrial water storage -- global river basins -- trends in water resources; Hydrology -- Periodicals; 333.91
• DOI: 10.1002/2016WR019494
• Languages: English
• ISSNs: 0043-1397

Abstract

Abstract: Recent developments in mascon (mass concentration) solutions for GRACE (Gravity Recovery and Climate Experiment) satellite data have significantly increased the spatial localization and amplitude of recovered terrestrial Total Water Storage anomalies (TWSA); however, land hydrology applications have been limited. Here we compare TWSA from April 2002 through March 2015 from (1) newly released GRACE mascons from the Center for Space Research (CSR‐M) with (2) NASA JPL mascons (JPL‐M), and with (3) CSR Tellus gridded spherical harmonics rescaled (sf) (CSRT‐GSH.sf) in 176 river basins, ∼60% of the global land area. Time series in TWSA mascons (CSR‐M and JPL‐M) and spherical harmonics are highly correlated (rank correlation coefficients mostly >0.9). The signal from long‐term trends (up to ±20 mm/yr) is much less than that from seasonal amplitudes (up to 250 mm). Net long‐term trends, summed over all 176 basins, are similar for CSR and JPL mascons (66–69 km 3 /yr) but are lower for spherical harmonics (∼14 km 3 /yr). Long‐term TWSA declines are found mostly in irrigated basins (−41 to −69 km 3 /yr). Seasonal amplitudes agree among GRACE solutions, increasing confidence in GRACE‐based seasonal fluctuations. Rescaling spherical harmonics significantly increases agreement with mascons for seasonal fluctuations, but less for long‐term trends. Mascons provide advantages relative to spherical harmonics, including (1) reduced leakage from land to ocean increasing signal amplitude, and (2) application of geophysical data constraints during processing with little empirical postprocessing requirements, making it easier for nongeodetic users. Results of this product intercomparison should allow hydrologists to better select suitable GRACE solutions for hydrologic applications. Key Points: Performance of new GRACE mascons in 176 global basins is shown to be equivalent to or superior to traditional‐scaled spherical harmonics Net long‐term trends from mascons summed over all basins agree (66–69 km 3 /yr) but are higher than spherical harmonics (14 km 3 /yr) Net depletion in total water storage occurs mostly in irrigated basins, ranging from −41 to −69 km 3 /yr among different GRACE solutions