[Spatiotemporal variation of reference evapotranspiration in Shanxi Province, China].

Based on data of daily precipitation, temperature, sunshine hours, relative humidity, wind speed and vapor pressure of 70 meteorological stations from 1960 to 2019 in Shanxi Province, the Penman-Monteith model was applied to calculate the reference evapotranspiration (ET). The spatiotemporal variations of ET as well as the ET in different climatic zones and at different altitudes were quantitatively analyzed. The results showed that the mean annual ET decreased from west to east in 1960-2019. A jumping point was detected in 1982, with the mean annual ET increased both in 1960-1982 and 1983-2019. The monthly and ten-day changes of ET showed single peak curves. The variation of ET in different climatic zones was as follows: ET in temperate and semi-arid areas was higher than that in warm temperate and semi-humid areas and warm temperate and semi-arid areas in spring, summer, autumn and the whole year, while in winter, the highest ET was in warm temperate and semi-humid areas. ET varied with altitudes, with ET in <660 m altitude areas being higher than that in other altitudes in summer, autumn, winter and the whole year.