A statistical collocation accuracy assessment of contemporary satellite temporal gravimetry data products

The Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) missions have enabled consistent production of monthly gravity field solutions by international institutes, contributing to the International Centre for Global Earth Models. Each institute employs distinct processing strategies, yielding varied estimates of terrestrial water storage (TWS). In this study, we employ statistical collocation techniques (Total assessment ratio, TAR) to assess and compare the performance of GRACE TWS data products (2003.03 ~ 2014.03) and GRACE-FO TWS data (2018.06 ~ 2022.11). For GRACE TWS, the TAR values are as follows: COST-G (0.15), ITSG (0.83), APM-SYSU (0.85), CSR (0.91), JPL (0.93), GFZ (0.94), Tongji (0.96), HUST (1.08), SUST (1.18), CNES (1.37), and AIUB (1.41). Similarly, for GRACE-FO TWS, the TAR values are COST-G (0.15), JPL (0.81), ITSG (0.96), CSR (0.97), GFZ (1.06), and CNES (1.41). Furthermore, our comparison across basin sizes and climatic regions reveals that COST-G exhibits lower uncertainty and larger signal-to-noise ratios in TWS, making it particularly noteworthy for its utility. Conversely, other single solutions that depict long-term trends and annual amplitudes demonstrate comparable values across various basin sizes, climatic regions, and specific areas.