An observational and reanalysis study of the water budget in the Amazon basin

Knowledge of evapotranspiration and latent heat fluxes is important to understanding the global water budget and global climate; however there are large discrepancies in latent heat flux estimates calculated using satellite derived values in certain areas of the globe. Observations of precipitation, runoff, surface evaporation and water vapor flux can provide more accurate estimates of latent heat flux, however these observations are often sparse, and in some parts of the world not taken at all. In this study, the Amazon River basin water budget for the surface and atmosphere is calculated using the NASA MERRA reanalysis dataset over a period of 53 months. Comparison between reanalysis and observed values of precipitation from GPCC, GPCP, and GHCN gauge networks and runoff from a discharge gauge in Obidos, Brazil are made and discussed. Based on the comparison between observed and reanalysis values, the residual surface evaporation and latent heat flux from the basin can be calculated from the observations.