Evolution of potential evapotranspiration in the northern Loess Plateau of China: recent trends and climatic drivers.

ABSTRACT Potential evapotranspiration represents the maximum evaporative capacity for a region, which underscores the importance of analysing its changes and attribution to provide information for water resource management. This study focused on the northern Loess Plateau of China, investigated the changes in potential evapotranspiration ( ET₀) using data from 34 stations during 1960-2013 and conducted its temporal and spatial attribution through the differentiation equation method. The results show that the annual mean ET₀ is 1004.9 mm with a decreasing trend at the rate of 0.33 mm year⁻¹. The lowest values were found in the northeast and southwest regions, while the greatest ET₀ was in the northwest region. An 'evaporation paradox' existed as a whole, but not obviously. The ET₀ was most sensitive to actual vapour pressure ( e_a), followed by solar radiation ( R_s), mean temperature ( T_mean) and wind speed ( U₂). The inter-annual variation in the sensitivity of ET₀ in relation to climatic factors showed that ET₀ became more sensitive to U₂ and T_mean but less sensitive to R_s and e_a from 1960 to 2013. Temporally, the increasing T_mean resulted in the increase of ET₀; while its effect was weakened by the other three factors, especially by decreasing U₂. The contributions of climatic factors to the ET₀ spatial variation trends were also analysed along two transects, but the dominant factors were different for each transect. Furthermore, the possible impacts of human activities on ET₀ changes were also discussed. [ABSTRACT FROM AUTHOR]