COMPARISON OF LAND WATER STORAGE CHANGES FROM GLOBAL HYDROLOGIC AND LAND SURFACE MODELS WITH OUTPUT FROM NEW GRACE SATELLITE SOLUTIONS

Increasing interest in global hydrology based on modeling and remote sensing underscores the need to compare results from these two approaches. Here we compare simulated land Total Water Storage anomalies (TWSA) from global hydrologic models (WGHM and PRC-GLOBWB) and land surface models (NOAH, MOSAIC, VIC, CLM, CLSM) to TWSA from newly released Gravity Recovery and Climate Experiment (GRACE) mascons solutions from Univ. of Texas Center for Space Research (CSR) and NASA Jet Propulsion Lab and from traditional spherical harmonic solutions. There is generally good agreement between modeled and GRACE-derived trends in TWSA in the midrange (within ±0.5 km3/yr) but models underestimate large declining and rising trends outside this range. Even global hydrologic models with human water use (PCR-GLOBWB and WGHM) show large differences in magnitude and direction of TWSA trends for many basins. There is much better agreement in seasonal amplitudes in TWSA between models and GRACE. Modeling human water use is important for long-term trends in many basins but not for seasonal amplitudes. This work will advance GRACE data processing and future model development that should provide improved understanding of global water resources.