Explaining the evaporation paradox in Jiangxi Province of China:Spatial distribution and temporal trends in potential evapotranspiration of Jiangxi Province from 1961 to 2013

Evaporation acts as an important component and a key control factor in land hydrological processes.In order to analyze the trend of change on potential evapotranspiration from 1961 to 2013 and to discuss the existence of the evaporation paradox in Jiangxi province,China,monthly meteorological data spanning the years 1961–2013 were analyzed in this study,where the data were collected from 15 national meteorological stations in Jiangxi Province.The Penman–Monteith equation was employed to compute the potential evapotranspiration(ET0).Spatial interpolation and data mining technology were used to analyze the spatial and temporal changes of ET0 and air temperature,with the effort to explain the evaporation paradox.By solving the total differential and the partial derivatives coefficients of the independent variables in Penman–Monteith equation,the cause of the paradox was quantitatively evaluated.The results showed that the annual ET0 had been decreasing significantly in Jiangxi Province since 1979,whereas the air temperature had been rising significantly,presenting the evaporation paradox.The decreases in sunshine duration and wind speed reduced ET0 by 0.207 mm and 0.060 mm,respectively,accounting for 92.3%and 26.7%of the total ET0,respectively.It is concluded that sunshine duration and wind speed are the main causes to the decrease in potential evapotranspiration in Jiangxi Province.