Journal of Resources and Ecology ›› 2011, Vol. 2 ›› Issue (3): 225-231.DOI: 10.3969/j.issn.1674-764x.2011.03.005

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Estimating Evapotranspiration Using Improved Fractional Vegetation Cover and Land Surface Temperature Space

SUN Liang1,2,3,4, SUN Rui1,2,3, LI Xiaowen1,2,3, CHEN Huailiang5, ZHANG Xuefen5   

  1. 1 State Key Laboratory of Remote Sensing Science, Beijing 100875, China;
    2 School of Geography, Beijing Normal University, Beijing 100875, China;
    3 Beijing Key Laboratory of Environmental Remote Sensing and City Digitalization, Beijing 100875, China;
    4 College of Global Change and Earth System Science, Beijing Normal University, Beijing 100875, China;
    5 Henan Institute of Meteorology, Zhengzhou 450003, China
  • Received:2011-06-27 Revised:2011-08-23 Online:2011-09-30 Published:2011-09-26
  • Contact: SUN Liang. Email: sunliang@mail.bnu.edu.cn.
  • Supported by:

    the National Natural Science Foundation of China (40971221), National Key Project of Scientific and Technical Supporting Programs Funded by Ministry of Science & Technology of China (2006BAD04B01-0101), National Department Public Benefit Research Foundation (GYHY200706046), the European Commission (Call FP7-ENV-2007-1 Grant No. 212921) as part of the CEOP-AEGIS project (http://www.ceop-aegis.org/), and the co-building projection of Beijing in China (000-105803).

Abstract: Vegetation index-land surface temperature (VI-Ts) space has been widely used to estimate evapotranspiration and soil moisture. The limitation of this method is the uncertainty of the observed dry edge, which is usually fitted by scatter plots. Here, a method was used to locate true dry and wet edges based on energy balance formulation, and a simple method to estimate surface energy flux is proposed based on the improved Fractional vegetation cover-Land surface temperature (Fv-Ts) space. Seventeen days of MODIS products were selected to estimate evapotranspiration and the estimated sensible heat flux (H) is compared with Large Aperture Scintillometer (LAS) data at a site in Zhengzhou, resulting in a RMSE of 44.06 W m-2, bias of 36.99 W m-2 and R2 of 0.71. The H scatter plots of estimation versus observation show clearly that most points are around the 1:1 line. Overall, the located true and wet edges are more accurate than the observed true edge. Our results can also be applied to improve the estimation of soil moisture.

Key words: evapotranspiration, sensible heat flux, land surface temperature (Ts), fractional vegetation cover (Fv)