Comparison of satellite-based evapotranspiration models over terrestrial ecosystems in China

 

Yang Chen^a,b, Jiangzhou Xia^a,b, Shunlin Liang^b,c, Jinming Feng^a,d, Joshua B. Fisher^e, Xin Li^f, Xianglan Li^b, Shuguang Liu^g, ZhuguoMa^d, Akira Miyata^h, Qiaozhen Muⁱ, Liang Sun^j, Jianwei Tang^k, Kaicun Wang^a,b, Jun Wen^f, Yueju Xue^l, Guirui Yu^m, Tonggang Zhaⁿ, Li Zhang^o, Qiang Zhang^k, Tianbao Zhao^d, Liang Zhao^p, Wenping Yuan^a,q

^a State Key Laboratory of Earth Surface Processes and Resource Ecology, College of Global Change and Earth System Science, Beijing Normal University, Beijing 100875, China;

^b State Key Laboratory of Remote Sensing Science, jointly Sponsored by Beijing Normal University and Institute of Remote Sensing Applications, Chinese Academic of Science, Beijing 100875, China;

^c Department of Geographical Sciences, University of Maryland, College Park, MD 20742, USA;

^d Key Laboratory of Regional Climate-Environment Research for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China;

^e Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA;

^f Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China;

^g State Engineering Laboratory of Southern Forestry Applied Ecology and Technology, Central South University of Forestry and Technology, Changsha, Hunan 410004, China;

^h National Institute for Agro-Environmental Sciences, Tsukuba 305-8604, Japan;

ⁱ College of Forestry & Conservation, The University of Montana, Missoula, MT 59812, USA;

^j Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China;

^k Meteorological Bureau of Gansu Province, Lanzhou, Gansu 730000, China;

^l College of Information, South China Agricultural University, Guangzhou 510642, China;

^m Key Laboratory of Ecosystem Network Observation and Modeling, Synthesis Research Center of Chinese Ecosystem Research Network, Institute of Geographic Sciences and Natural Resources

Research, Chinese Academy of Sciences, Beijing 100101, China;

ⁿ School of Resources and Environment, Beijing Forestry University, Beijing 100083, China;

^o Center for Earth Observation and Digital Earth, Chinese Academy of Sciences, Beijing 100094, China;

^p Key Laboratory of Qinghai-Tibetan Plateau Biological Evolution and Adaptation, Northwest Institute of Plateau Biology, The Chinese Academy of Sciences, Xining, Qinghai 810008, China;

^q State Key Laboratory of Cryosphere Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, The Chinese Academy of Sciences, Lanzhou, Gansu 730000, China.

 

Abstract: Evapotranspiration (ET) is a key component of terrestrial ecosystems because it links the hydrological, energy, and carbon cycles. Several satellite-based ET models have been developed for extrapolating local observations to regional and global scales, but recent studies have shown large model uncertainties in ET simulations. In this study, we compared eight ET models, including five empirical and three process-based models, with the objective of providing a reference for choosing and improving methods. The results showed that the eight models explained between 61 and 80% of the variability in ET at 23 eddy covariance towers in China and adjacent regions. The mean annual ET for all of China varied from 535 to 852 mm yr⁻¹ among the models. The interannual variability of yearly ET varied significantly between models during 1982–2009 because of different model structures and the dominant environmental factors employed. Our evaluation results showed that the parameters of the empirical methods may have different combination because the environmental factors of ET are not independent. Although the three process-based models showed high model performance across the validation sites, there were substantial differences among them in the temporal and spatial patterns of ET, the dominant environment factors and the energy partitioning schemes. The disagreement among current ET models highlights the need for further improvements and validation, which can be achieved by investigating model structures and examining the ET component estimates and the critical model parameters.

 

Keywords: Evapotranspiration; Eddy covariance; Priestley–Taylor; Penman–Monteith.

 

Published in Remote Sensing of Environment. 2014, 140: 279-293.