Changes of Evapotranspiration in Amazonia for the past four decades

The Amazonia plays an important role in the functioning of the Earth's climate, influencing both global water and carbon cycles. As a key component of the water cycle, evapotranspiration(ET), especially that over Amazonia, is of great scientific significance. However, based on our preliminary analysis, there are large discrepancy in ET trends over Amazonia among the previous observation-based reconstructions of global ET products. Here, we will reconstruct ET using an ensemble of several remote sensing ET products over Amazon and use eddy covariance flux measurements for validation of satellite ET products. Based on the reconstructions of ET, we will analyze and confirm the magnitude, interannual variability, long-term trends and temporal characteristics of ET in Amazonia using statistical method. Additionally, we will try to figure out what are the driving factors(such as deforestation, greening, CO2 fertilization, warming, precipitation, radiation changes, and etc) for the ET trend by sensitivity analysis. The study of ET is helpful to further understand the mechanism of land-air interaction, surface energy balance, and to correctly assess the impact of human activities in the context of global change.