Estimating Evapotranspiration Using Canopy Temperatures: Field Evaluation
- L. R. Stone and
- M. L. Horton
Evapotranspiration generally has been estimated on a small scale because of cost and time required for measurements. Thermal scanners provide a possible way of estimating water loss from surfaces by using remotely sensed surface temperatures. In this study, designed to evaluate the feasibility of using canopy temperatures in estimating evapotranspiration (ET), we employed five equations. Sorghum bicolor L (Moench) was used in the field investigation. Three of the equations were the well-known methods of van Bavel, Penman, and energy budget-Bowen ratio. The other two use the temperature of the evaporating surface in estimating ET and are referred to as the Bartholic-Namken-Wiegand (B-N-W) and Brown-Rosenberg (B-R) methods. Using simple linear regression and correlation analyses, we found the B-N-W estimates to be approximately 17% smaller and the B-R estimates to be approximately 22% larger than typical estimates obtained by the Penman and energy budget-Bowen ratio methods. Both methods appear usable in determining ET rates of vegetated surfaces, with the B-N-W method requiring less input data than the B-R method.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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