Benchmarking multimodel terrestrial water storage seasonal cycle against GRACE observations over major global river basins
Abstract. The increasing reliance on global models for evaluating climate and human-induced impacts on the hydrological cycle underscores the importance of assessing their reliability. Hydrological models provide valuable data on ungagged river basins or basins with limited gauge networks. The objective of this study was to evaluate the reliability of 13 global models using the Gravity Recovery and Climate Experiment (GRACE) satellites total water storage (TWS) seasonal cycle for 29 river basins in different climate zones. Results show that the simulated seasonal total water storage change (TWSC) does not compare well with GRACE even in basins within the same climate zone. The models overestimated the seasonal amplitude in most boreal basins and underestimated it in tropical, arid, and temperate zones. In cold basins, the modeled phase of TWSC precedes that of GRACE by up to 2–3 months. However, it lags the GRACE phase by one month over temperate, arid to semi-arid basins. There was good agreement between GRACE and model amplitudes in the tropical zone. With the findings and analysis, we concluded that R2 models with optimized parametrizations have a better correlation with GRACE than the reverse scenario. This signifies an enhancement in the predictive capability of models regarding the variability of TWSC. The seasonal amplitude and phase-difference analysis in this study provide new insights into the future improvement of large-scale hydrological models and TWS investigations.
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