Vegetation index-land surface temperature （VI-T s ） 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 us...Vegetation index-land surface temperature （VI-T s ） 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 （F v -T s ） 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 R^2 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.展开更多
基金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)+2 种基金National Department Public Benefit Research Foundation(GYHY200706046)the European Commission(Call FP7-ENV-2007-1Grant No.212921)as part of the CEOP-AEGIS project(http://www.ceop-aegis.org/)the co-building projection of Beijing in China(000-105803)
文摘Vegetation index-land surface temperature （VI-T s ） 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 （F v -T s ） 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 R^2 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.
