Spatial and temporal characteristics of potential evapotranspiration trends over China

This paper analyses the time series (1954–1993) of Penman–Monteith evapotranspiration estimates for 65 stations in mainland China and Tibet, for the country as a whole and for individual stations. The analysis shows that for China as a whole, the potential evapotranspiration (PET) has decreased in all seasons. On a regional basis, northeast and southwest China have experienced moderate evapotranspiration increases, while in northwest and southeast China evapotranspiration has decreased to a much higher extent. South of 35°N, sunshine appears to be most strongly associated with evapotranspiration changes while wind, relative humidity and maximum temperature are the primary factors in northwest, central and northeast China, respectively. In the mountains of southwest China, a positive relation between evapotranspiration change and station altitude has been observed. If observed precipitation and PET trends remain unchanged future agricultural production, particularly in south and southwest China, will have to cope with decreasing water availability in the growing season.