Using Satellite Observations to Assess Applicability of GLDAS and WGHM Hydrological Model

GLDAS and WGHM hydrological products from January 2002 to December 2012 are investigated with GRACE satellite observations to study the terrestrial water storage anomalies (TWSA) in 30 major river basins worldwide. GLDAS and WGHM model outputs are compared and evaluated in terms of annual amplitude, long-term trend and spatial-temporal consistency with GRACE observations. The results show that the four land surface models in GLDAS show an obvious seasonal cycle in TWSA, among which the amplitudes of CLM is the smallest, MOSAIC and VIC are largest, and NOAH is in middle which exhibits the strongest consistency to the average GLDAS estimates. Compared with the GRACE results, the annual amplitudes are obviously underestimated by both GLDAS and WGHM in most river basins, and the underestimation degree of GLDAS is greater than that of WGHM. Also, the opposite situation occurs in river basins located near the Arctic. In terms of long-term trend, the results of the three models are quite different, especially for river basin with small area and strong human intervention, GLDAS and WGHM are not capable enough of reflecting the impact of human activities and their output performances are poor, while the GRACE results are closer to the actual situation. It is also found that the river basins with obvious downward trends are mainly concentrated in the areas with high irrigation rate (>10%).