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

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 on empirical models to predict solar radiation. These alternative methods were compared to the FAO Penman-Monteith method by using more than 80 yr of historical weather data. Alternative methods were adapted from the standard 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.

Keywords
FAO Penman-Monteith; meteorological variables; reference evapotranspiration; solar radiation models