Changes of actual evapotranspiration and its components in the Yangtze River valley during 1980–2014 from satellite assimilation product

Abstract

Evapotranspiration (ET) is an important process of water and energy exchanges between land and atmosphere. In this study, a processed-based GLEAM (global land-surface evaporation: the Amsterdam methodology) satellite assimilation product has been validated in the Yangtze River valley on the observations of flux and the water balance method. The changes of total ET and its components, well as the associated dynamics, have been analyzed for the period of 1980–2014. The total ET shows significant increasing trends especially in the middle and lower reaches of the Yangtze River valley, which is mostly due to the increase of transpiration. The spatial and temporal dynamics of total ET are analyzed with respect to temperature, precipitation, and solar radiation. The spatial pattern of total ET in the Yangtze River valley is found to be jointly determined by temperature and precipitation. As for the temporal dynamics, precipitation plays the dominant role in total ET in the source regions of the valley. While in the most regions, solar radiation is suggested to be a main controller, in the positive manner, of total ET. This may provide an in-depth understanding of ET changes in the warming climate, and form a basis for water resource management in the Yangtze River valley.