GRACE‐based Mass Conservation as a Validation Target for Basin‐Scale Evapotranspiration in the Contiguous United States
Madeleine Pascolini‐Campbell, J. T. Reager, Joshua B. Fisher
Abstract
Abstract Here, we evaluate basin‐scale evapotranspiration (ET) estimates for eleven major river basins in the contiguous United States against a water balance approach with Gravity Recovery and Climate Experiment (GRACE) satellite observations. The relatively precise measurements of large‐scale changes in water mass from GRACE are used to estimate the storage rate term in the terrestrial water budget and consequently provide an estimate, with propagated uncertainty, of basin‐aggregated ET from mass conservation. We apply GRACE‐based ET to two modeling systems (NLDAS‐2 and GLDAS‐2.1) comprised of five land surface models and three remote sensing‐based products (MOD16, PT‐JPL, and FLUXCOM) for 2003 to 2014. Both the land surface model‐based and remote sensing‐based ET are persistently lower than GRACE‐based ET in all eleven basins tested. We also find that interannual variability is greater for GRACE‐ET than the model and remote sensing products, and this is attributed to precipitation variability.