where: ETp = mean daily potential evapotranspiration (mm/day);
Rs = daily global (total) solar radiation (kJ/m2/day);
Ta = mean daily air temperature (°C). Comparative calculations
based on the Jensen-Haise method (Jensen and Haise, 1963) and the Solar
Thermal Units method (Caprio, 1974), both based on the same independent
parameters, reveal very similar results. The method has been shown to estimate
potential evapotranspiration very accurate, compared to other empirical
methods (Schroedter, 1985).
| Command: | &r etp_trc (at GRID prompt) |
| Required input: | Grids of avg. temperature, and of global radiation |
| Output units: | 1/10 mm/day |
| Speed of calculations: | Fast due to optimized programming |
| Flexibility of the routine: | High; user can adjust AML at interface |
| User interface: | Limited, but simple and easy |
| Known errors: | - |
| Programmer | N.E. Zimmermann |
| Download: | etp_trc.aml (use: "save link as") |
| Contact: | niklaus.zimmermann @ wsl.ch |
References:
Caprio, J.M., 1974. The Solar Thermal Unit Concept in Problems Related to Plant Development and Potential Evapotranspiration. In: H. Lieth (Editor), Phenology and Seasonality Modeling. Ecological Studies. Springer Verlag, New York, pp. 353-364.Last Updated: 9/08/00Jensen, M.E. and Haise, H.R., 1963. Estimating evapotranspiration from solar radiation. J. Irrig. Drainage Div. ASCE, 89: 15-41.
Schrödter, H. 1985: Verdunstung. Anwendungsorientierte Messverfahren und Bestimmungsmethoden. Springer Verag, Berlin, 186pp.
Turc, L., 1963. Evaluation des besoins en eau d'irrigation, évapotranspiration potentielle, formulation simplifié et mise à jour. Ann. Agron., 12: 13-49.