Water Balance in the Amazon Basin from a Land Surface Model Ensemble

Augusto C. V. Getirana , Emanuel Dutra (1) , Matthieu Guimberteau (2) , Jonghun Kam , Hong-Yi Li (3) , Bertrand Decharme (4) , Zhengqiu Zhang , Agnès Ducharne (2) , Aaron Anthony Boone (4) , Gianpaolo Balsamo (1) , Matthew Rodell (5) , Ally M. Toure , Yongkang Xue (6) , Christa D. Peters-Lidard , Sujay V. Kumar , Kristi Arsenault , Guillaume Drapeau (7) , L Ruby Leung , Josyane Ronchail (8, 9) , Justin Sheffield

1 ECMWF - European Centre for Medium-Range Weather Forecasts
2 METIS - Milieux Environnementaux, Transferts et Interactions dans les hydrosystèmes et les Sols
3 Niglas - Nanjing Institute of Geography and Limnology
4 CNRM - Centre national de recherches météorologiques
5 GSFC - NASA Goddard Space Flight Center
6 Department of Geography [Los Angeles]
7 PRODIG (UMR_8586 / UMR_D_215 / UM_115) - Pôle de recherche pour l'organisation et la diffusion de l'information géographique
8 PARVATI - Processus de la variabilité climatique tropicale et impacts
9 UPD7 - Université Paris Diderot - Paris 7

Despite recent advances in land surface modeling and remote sensing, estimates of the global water budget are still fairly uncertain. This study aims to evaluate the water budget of the Amazon basin based on several state-of-the-art land surface model (LSM) outputs. Water budget variables (terrestrial water storage TWS, evapotrans-piration ET, surface runoff R, and base flow B) are evaluated at the basin scale using both remote sensing and in situ data. Meteorological forcings at a 3-hourly time step and 18 spatial resolution were used to run 14 LSMs. Precipitation datasets that have been rescaled to match monthly Global Precipitation Climatology Project (GPCP) and Global Precipitation Climatology Centre (GPCC) datasets and the daily Hydrologie du Bassin de l'Amazone (HYBAM) dataset were used to perform three experiments. The Hydrological Modeling and Analysis Platform (HyMAP) river routing scheme was forced with R and B and simulated discharges are compared against observations at 165 gauges. Simulated ET and TWS are compared against FLUXNET and MOD16A2 evapotranspi-ration datasets and Gravity Recovery and Climate Experiment (GRACE) TWS estimates in two subcatchments of main tributaries (Madeira and Negro Rivers). At the basin scale, simulated ET ranges from 2.39 to 3.26 mm day 21 and a low spatial correlation between ET and precipitation indicates that evapotranspiration does not depend on water availability over most of the basin. Results also show that other simulated water budget components vary significantly as a function of both the LSM and precipitation dataset, but simulated TWS generally agrees with GRACE estimates at the basin scale. The best water budget simulations resulted from experiments using HYBAM, mostly explained by a denser rainfall gauge network and the rescaling at a finer temporal scale.

Domaines: Sciences de l'environnement; Hydrologie; Météorologie

Augusto C. V. Getirana, Emanuel Dutra, Matthieu Guimberteau, Jonghun Kam, Hong-Yi Li, et al.. Water Balance in the Amazon Basin from a Land Surface Model Ensemble. Journal of Hydrometeorology, 2014, 15 (6), pp.2586-2614. ⟨10.1175/JHM-D-14-0068.1⟩. ⟨hal-02267740⟩