Articles | Volume 368
Proc. IAHS, 368, 379–384, 2015
https://doi.org/10.5194/piahs-368-379-2015
Proc. IAHS, 368, 379–384, 2015
https://doi.org/10.5194/piahs-368-379-2015

  07 May 2015

07 May 2015

Combining the trapezoidal relationship between land surface temperature and vegetation index with the Priestley-Taylor equation to estimate evapotranspiration

X. Wang, W. Wang, and Y. Jiang X. Wang et al.
  • State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098, China

Keywords: Actual evapotranspiration, land surface temperature‚ąívegetation index trapezoid, Priestley-Taylor equation, remote sensing

Abstract. Evapotranspiration (ET) plays an important role in the hydrological cycle. A method of combining the Priestley-Taylor (P-T) equation with a trapezoidal space between land surface temperature (Ts) and enhanced vegetation index (EVI) is proposed based on the principle of energy balance. Generally, this method is divided into three major parts: (1) construct the Ts versus EVI (Ts-VI) trapezoidal space for calculating the Ts at four extreme conditions (i.e. well-watered vegetation, water-stressed vegetation, saturated bare soil and dry bare soil); (2) calculate the P-T coefficient for each pixel according to the position of the observed (EVI, Ts) point in the trapezoid space; (3) calculate actual ET of the pixel using the P-T equation. The method is validated using Landsat-8 images and ground-observed data for a semi-humid area in China. The result shows that the ET estimates match the observations well, which indicates the effectiveness the proposed method here.

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