Temporal Characteristics of Actual Evapotranspiration Over China Under Global Warming

In this study, an assessment is made of the trends of actual evapotranspiration (AE) over China under global warming from an ensemble of the following data sets: National Centers for Environmental Prediction-National Center for Atmospheric Research reanalysis I, National Centers for Environmental Prediction-Department of Energy reanalysis II, Modern-Era Retrospective Analysis for Research and Applications (MERRA), MERRA Version 2, European Centre for Medium-Range Weather Forecasts Interim Re-Analysis, and Japanese 55-year Reanalysis. For China as a whole, annual AE exhibited a significant increasing trend from 1979 to 2015, and the rate of increase was highest in autumn and lowest in summer. By subdividing China into six climatic regions using the aridity index, significant increasing trends in AE are found over the hyperarid, arid, and humid regions, but slightly decrease over the dry subhumid and subhumid regions. For the hyperarid and arid regions, the increases in potential evapotranspiration and the water supply from melting glaciers due to both climate warming and human activities might be the main contributors to the AE increases. An increase in potential evapotranspiration driven by global warming is the main cause of the increased AE over the humid region. On a seasonal basis, most AE over China occurs in summer. However, increasing AE trends have been observed mainly in autumn and winter, and the increase is statistically significant over all of China's six climatic regions in winter. In view of data availability, reanalyses are compared with the results from Mezentsev-Choudhury-Yang equation (AE_Budyko). The correlations between individual reanalyses and AE_Budyko tend to be higher over the arid region.