Sensitivity analysis of reference evapotranspiration (ETo) to climate change in Beijing, China

Abstract

In the present study, an attempt has been made to study the reference evapotranspiration (ETo) change and the sensitivity of estimated ETo to each climatic variable in a semi-humid and semi-arid region of Beijing in the north China using data from 1951 to 2010. Results show that in the past 60 years, yearly ETo was increasing with a rate of 19.5mm per decade, and seasonal total ETo in wheat and corn seasons were increasing with rates of 13.1 and 5.3mm per decade, respectively. Sensitivity analysis showed that mean air temperature was the first key factor for ETo change in the past 60 years, causing an annual total ETo increase of 7.4%, followed by relative humidity (5.5%) and sunshine hours (–3.1%); the less sensitivity factors were wind speed (0.7%), minimum temperature (–0.3%), and maximum temperature (–0.2%). A greater increase of total ETo (12.3%) in the past 60 years was found in wheat season, mainly because of mean temperature (8.6%) and relative humidity (5.4%), as compared to an increment of 6.0% in ETo during corn season due to sunshine hours (–6.9%), relative humidity (4.7%), and temperature (4.5%).