Estimation of Evapotranspiration in the Amazon River Basin Using the Atmospheric Water Balance Method

This study investigates the seasonal changes of evapotranspiration in the Amazon river basin during the FGGE period.The relationship between basin storage and evapotranspiration is also investigated.The atmospheric water balance method and that of the basin are used for the analysis, using the global objective analyzed data set, precipitation data and discharge data.Since the seasonal change pattern of precipitation shows good correspondence to that of water vapor flux convergence, monthly evapotranspiration remains almost constant within a year.On the other hand, the seasonal changes of basin storage are very great and it is concluded that evapotranspiration in the entire Amazon river basin is not affected by the seasonal changes of basin storage even in the dry season.It is also found that the role of evapotranspiration in the water cycle in the basin is relatively more important in the dry season than in the rainy season.