Trend of estimated actual evapotranspiration over China during 1960-2002

Abstract

In this study, the water balance methodology introduced by Thornthwaite and Mather (1955) is modified to estimate monthly actual evapotranspiration for 686 stations over China during 1960-2002. The modification is done by replacing the Thornthwaite potential evapotranspiration estimation with the Penman-Monteith method. Temporal trend and spatial distribution of the estimated annual actual evapotranspiration during the past 43 years are analyzed. The results show that (1) the actual evapotranspiration had a decreasing trend in most areas past of 100°E, and there was an increasing trend in the west and the north parts of northeast China; (2) the spatial distribution of the trend for the actual evapotranspiration is similar to that of the potential evapotranspiration in south China, while the trends are opposite in north China; (3) for most parts of China, the change in precipitation played a key role for the change of estimated actual evapotranspiration, while in southeast China, the change of potential evapotranspiration appeared to be the major factor, and (4) in general, the hydrological cycle was intensified in western China, whereas it was weakened from the Yellow River basin northward. Copyright 2007 by the American Geophysical Union.