Comparação de equações que estimam a evapotranspiração de referência (ETo) com o modelo de Penman-Monteith padrão FAO nas condições do município de Areia-PB

Abstract

The main objective of this study was to compare the reference evapotranspiration (ETo), estimated by the Blaney & Criddle, Priestley-Taylor, Hargreaves & Samani and the class "A" Tank equations, with those estimated by the Standard FAO Penman-Monteith model in Areia-PB conditions. To achieve this goal, average monthly weather data of the maximum, average and minimum air temperatures, relative humidity, wind, precipitation and sunshine, series 1998-2007, obtained from the meteorological station of the CCA / UFPB were processed and analyzed for the calculation of ETo and other variables. It used to estimate reference evapotranspiration the program Reference Evapotranspiration Calculator (Ref-ET). The ETo estimated by all methods studied, except for the model Blaney & Criddle, overestimated ETo determined by the standard model of Penman-Monteith-FAO, recommended for calibration of the other methods. The coefficient of determination (R2) of all models analyzed was higher than 0.90, with emphasis on the method of Priestley & Taylor. This model had a coefficient of determination of 0.9806. Comparing the equations studied by calculating the index "c" of Willmott, mean absolute error (MPE) and maximum error (ME), it was observed that the methodology of Blaney & Criddle showed the best performance with the index c = 0.89, which is considered very good, followed by Class "A" Tank with c = 0.62, Hargreaves & Samani with c = 0.60 and Priestley-Taylor with c = 0.55, ranked with average performance.