A comparison of different GRACE solutions in terrestrial water storage trend estimation over Tibetan Plateau

The Gravity Recovery and Climate Experiment (GRACE) terrestrial water storage anomalies (TWSA) estimations provide valuable information for the monitoring of land water resources changes. Multiple parameters and strategies for inversion of the water storage changes have been explored. The explorations on differences between GRACE solutions in local regions and basins are fundamental and important. This study focuses on comparisons of TWSA trends between different GRACE solutions over Tibetan Plateau (TP), both storage and flux among solutions were compared. Results show that great discrepancies exist in TWSA between GRACE solutions derived from the standard spherical harmonic approach (SSH) and the mascon approach. Three SSH-based GRACE solutions (JPL, CSR, and GFZ) detect no significant TWSA changes for the whole area of Tibetan Plateau, whereas JPL mascon solution (JPL-M) and CSR mascon solution (CSR-M) gave decreasing trends of 3.10 km³/yr and 3.77 km³/yr, respectively. This difference also exists in the Yangtze River-Yellow River basin (YYR basin) in the TP. Although five solutions derived consistent TWSA trends in northwest river basin (NWR basin) and southwest river basin (SWR basin) in the TP, the variations between different solutions are 2.88 km³/yr and 4.75 km³/yr for NWR and SWR basin respectively, which could not be neglected. The JPL-M solution, as a result, would overestimate both TWSA decreasing and increasing trends comparing with other GRACE solutions. The results of this study are expected to provide references for the studies of water resource dynamics over Tibetan Plateau and the surrounding areas based on GRACE TWSA products.