Identification of dominant climate factor for pan evaporation trend in the Tibetan Plateau

作     者：LIU Xiaomang ZHENG Hongxing ZHANG Minghua LIU Changming 

作者机构：Institute of Geographic Sciences and Natural Resources Research CAS Beijing 100101 China Department of Land Air and Water Resources University of California Davis CA 95616 USA 

出 版 物：《Journal of Geographical Sciences》 (地理学报（英文版）)

年 卷 期：2011年第21卷第4期

页      面：594-608页

核心收录：

学科分类：0709[理学-地质学] 08[工学] 081501[工学-水文学及水资源] 09[农学] 090101[农学-作物栽培学与耕作学] 0815[工学-水利工程] 0901[农学-作物学] 0704[理学-天文学] 

基　　金：The European Commission (Call FP7-ENV-2007-1), No.212921 National Basic Research Program of China, No.2010CB428406 

主　　题：pan evaporation trend reference evapotranspiration attribution the Tibetan Plateau 

摘      要：Despite the observed increase in global temperature, observed pan evaporation in many regions has been decreasing over the past 50 years, which is known as the ＂pan evaporation paradox＂. The ＂pan evaporation paradox＂ also exists in the Tibetan Plateau, where pan evaporation has decreased by 3.06 mm a-2 （millimeter per annum）. It is necessary to explain the mechanisms behind the observed decline in pan evaporation because the Tibetan Plateau strongly influences climatic and environmental changes in China, Asia and even in the Northern Hemisphere. In this paper, a derivation based approach has been used to quantitatively assess the contribution rate of climate factors to the observed pan evaporation trend across the Tibetan Plateau. The results showed that, provided the other factors remain constant, the increasing temperature should have led to a 2.73 mm a-2 increase in pan evaporation annually, while change in wind speed, vapor pressure and solar radiation should have led to a decrease in pan evaporation by 2.81 mm a-2, 1.96 mm a-2 and 1.11 mm a-2 respectively from 1970 to 2005. The combined effects of the four climate variables have resulted in a 3.15 mm a-2 decrease in pan evaporation, which is close to the observed pan evaporation trend with a relative error of 2.94%. A decrease in wind speed was the dominant factor for the decreasing pan evaporation, followed by an increasing vapor pressure and decreasing solar radiation, all of which offset the effect of increasing temperature across the Tibetan Plateau.