Spatial distribution of potential evapotranspiration trends in the Inner Mongolia Autonomous Region (1971–2016)

Evapotranspiration is a critical hydrological and meteorological variable impacted by climate change. In this study, the annual potential evapotranspiration (ET o ) was estimated using the Penman-Montieth method at 104 meteorological stations in Inner Mongolia, China, from 1971 to 2016. The characteristics of seasonal and annual ET o were analyzed using the least squares method and trends of ET o , and its driving meteorological factors were investigated using the Mann-Kendall test. The most influential meteorological factors driving ET o were identified using stepwise regression and partial correlation analysis. Results showed that the annual average (range) ET o was approximately 1050 mm (996–1165 mm), and air temperature was approximately 4 °C (3.25–6.01 °C). ET o decreased over time, suggesting that the evaporation paradox exists. The ETo in summer was the largest followed by that in spring, autumn, and winter. Relative humidity, precipitation, sunshine duration, minimum temperature, maximum temperature, and mean temperature were the main factors influencing the distribution of ET o . Trends of ET o showed a high degree of spatial variability; however, stations showing significant negative trends were generally concentrated in central Inner Mongolia. At an annual time scale, decreased wind speed and sunshine duration were the most important drivers of reduced ET o .