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Reference evapotranspiration trends and their sensitivity to climatic change on the Tibetan Plateau (1970–2009)
Author(s) -
Xie Hong,
Zhu Xuan
Publication year - 2012
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.9487
Subject(s) - evapotranspiration , plateau (mathematics) , wind speed , environmental science , precipitation , atmospheric sciences , relative humidity , climate change , climatology , meteorology , geography , mathematics , physics , geology , mathematical analysis , ecology , oceanography , biology
Evapotranspiration is an important component of the water and energy balance. It is dependent on climate. Precipitation, solar radiation, temperature, humidity, and wind all contribute to the rate of evapotranspiration. In this study, the temporal trends of reference evapotranspiration ( ET ref ) and four main ET ref drivers, namely, mean air temperature ( T a ), wind speed ( u 2 ), net radiation ( R n ) and actual vapour pressure ( e a ) from 1970 to 2009, were calculated based on 75 meteorological stations on the Tibetan Plateau. The results showed that the ET ref on the Tibetan Plateau decreased on average by 0.6909 mm a ‐1 a ‐1 from 1970 to 2009. T a and e a showed an increasing trend, whereas u 2 and R n exhibited a decreasing trend. To explore the underlying causes of the ET ref variation, an attribution analysis was performed to quantify the contribution of T a , u 2 , R n and e a , which showed that the changes in u 2 , R n and e a produced the negative effect, whereas T a produced the positive effect on ET ref rates. The changes in u 2 were found to produce the largest decrease (−0.7 mm) in ET ref , followed by e a (−0.4 mm) and R n (−0.1 mm). Although the significant increase in T a had a large positive effect (0.51 mm) on ET ref rates, changes in the other three variables each reduced ET ref rates, resulting in an overall negative trend in ET ref . Copyright © 2012 John Wiley & Sons, Ltd.