The climatic characterization of reference evapotranspiration of beijing meteorological station

Abstract

Analysis of the climatic characterization of reference evapotranspiration (ETp) is significant for understanding the impact of climate change on water cycle. Based on the Penman-Monteith method, this paper estimates ETp at Beijing meteorological station and analyzes its annual and intra-annual variation. Furthermore, the causes of variation of ETp are analyzed and quantified using the detrending method and the combination method that consider both the sensitivity coefficient and the fluctuation of the climatic variables. The obtained results show that ETp increased significantly during 1951-2009. At the same time, air temperature had a significant increasing trend; relative humidity and solar radiation showed a significant decreasing trend at 5% significance level, while wind speed had no significant trend. The contributions of air temperature, relative humidity, solar radiation and wind speed to the ETp intra-annual variation is 60%, -82%, 51% and 71%, respectively. However, the sensitivity analysis shows that wind speed is the least sensitive factor, but it has larger fluctuation than the other variables. So the contribution to the annual or intra-annual variation is not only determined by the sensitivity of those climatic variables, but also by their annual trends or intra-annual fluctuations. © 2012 Springer-Verlag GmbH.