What Controls Evapotranspiration in the Amazon Basin

Evapotranspiration (ET) is an important meteorological variable and a key element in assessing the water cycle over a region, though not yet well known over the Amazon river basin. Previous studies have mainly used radiation observations to estimate ET, which generally assumes that there is no soil water limitation for plant transpiration. As part of the LBA experiment, several towers were equipped to perform eddy-covariance measurements of carbon and energy fluxes. We use these different measurements of water fluxes to compare ET across sites over the Amazon and understand latitudinal variations in ET. Results are also compared to radiation-estimated ET to test the soil water availability assumption. Finally, measured ET are compared to simulated climate models output to understand how well and where the models are able to reproduce the measured ET and why.