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

摘要

Potential evapotranspiration (ET0) is a key component of the water cycle and a main factor to water resources assessment. Analysis of variation inET0is 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 ofET0in the Jing-Jin-Ji region (Beijing Municipality, Tianjin Municipality, and Hebei Province), values ofET0and other climatic parameters at 22 national meteorological stations from 1961 to 2015 were analyzed. Cramer’s test showed a shift point in theET0data at approximately 1991. AnnualET0decreased from 1961 through 1991 at a rate of ?20.95?mm per decade, but annualET0increased 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 forET0, and to reveal the causes of change inET0. From 1961 to 1991, the decrease of wind speed and sunshine duration offset the effect of increased air temperature, leading to reducedET0.However, from 1992 to 2015, average air temperature was the most dominant factor contributing to the increase inET0. Increased of air temperature and wind speed, and decreased relative humidity caused an increase inET0. This change inET0could impact hydrological cycle and agriculture irrigation management in the Jing-Jin-Ji region.