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Reference evapotranspiration estimates based on minimum meteorological variable requirements from historical weather data

Antonio J. Steidle Neto1*, João C.F. Borges Júnior1, Camilo L.T. Andrade2, Daniela C. Lopes1, and Priscilla T. Nascimento1

Reference evapotranspiration (ET0) is critical for agricultural and urban planning, irrigation scheduling, regional water balance studies, and agroclimatological zoning. The objective of this study was to estimate ET0 based on methods with minimum meteorological variable requirements and empirical models to predict solar radiation. These alternative methods were compared to the FAO Penman-Monteith method based on more than 80 yr of historical weather data. Alternative methods were adapted from the original FAO Penman-Monteith or Priestley-Taylor methods, which allow estimating ET0 when fewer meteorological variables are available. The Hargreaves-Samani method was also analyzed. The mean absolute error, index of agreement, correlation coefficient, and confidence index were used to compare the alternative methods. Results showed that alternative methods based on the maximum and minimum temperatures, sunshine hours, and/or wind speed are appropriate for estimating ET0 in the region under study.

Key words: FAO Penman-Monteith, meteorological variables, reference evapotranspiration, solar radiation models.

1Universidade Federal de São João del-Rei, Campus Sete Lagoas, Rodovia MG 424, km 47, Sete Lagoas, 35701-970, Minas Gerais, Brasil. *Corresponding author (antonio@ufsj.edu.br).
2Embrapa Milho e Sorgo, Rodovia MG 424, km 45, Sete Lagoas, 35702-098, Minas Gerais, Brasil.

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