Spatio-temporal variation of potential evapotranspiration and climatic drivers in the Jing-Jin-Ji region, North China

Abstract Potential evapotranspiration ( ET 0 ) is a key component of the water cycle and a main factor to water resources assessment. Analysis of variation in ET 0 is significant in understanding the climate change and agricultural water management; It is affected by multiple climatic factors, including air temperature, relative humidity, wind speed, and sunshine duration. To understand the variations of ET 0 in the Jing-Jin-Ji region (Beijing Municipality, Tianjin Municipality, and Hebei Province), values of ET 0 and other climatic parameters at 22 national meteorological stations from 1961 to 2015 were analyzed. Cramer’s test showed a shift point in the ET 0 data at approximately 1991. Annual ET 0 decreased from 1961 through 1991 at a rate of −20.95 mm per decade, but annual ET 0 increased at a rate of 7.40 mm per decade from 1992 to 2015. Partial correlation analysis and multiple linear regression methods were used to determine the dominant climatic driving factors for ET 0 , and to reveal the causes of change in ET 0 . From 1961 to 1991, the decrease of wind speed and sunshine duration offset the effect of increased air temperature, leading to reduced ET 0. However, from 1992 to 2015, average air temperature was the most dominant factor contributing to the increase in ET 0 . Increased of air temperature and wind speed, and decreased relative humidity caused an increase in ET 0 . This change in ET 0 could impact hydrological cycle and agriculture irrigation management in the Jing-Jin-Ji region.