Resumo

KELSO-BUCIO, Henry A.; BA, Khalidou M.; SANCHEZ-MORALES, Saúl  e  REYES-LOPEZ, Delfino. Exponent calibration of Hargreaves-ETo equation in the states of Chiapas, Oaxaca, Puebla and Veracruz, México. Agrociencia [online]. 2012, vol.46, n.3, pp.221-229. ISSN 2521-9766.

A recalibration was made of the empirical exponent (HE) of the Hargreaves-ETo equation (HG) to obtain appropriate results in the estimation of reference evapotranspiration (ETo). The HG equation was selected due to its simplicity, given that to estimate ETo, only a minimum of climatological variables are required, commonly available in all of the meteorological stations. The objective of the present study was to recalibrate the HE exponent of the Hargreaves-ETo equation for different localities of the Mexican republic. In addition the HG and corrected HG (HG_HE) methods were compared to define the improvement in ETo prediction. The meteorological data used are from the National Network of Modeling and Remote Sensors (LNySR) of the INIFAP from five stations of the state of Chiapas, nine from the state of Oaxaca, 16 from the state of Puebla and seven from the state of Veracruz. In the comparison of the methods of HG and HG_HE, an analysis was made the indicators of the mean bias of the error (MBE), relative error (RE), mean square error (RMSE), standard deviation of the error (SEE), correspondence index (D) and the quotient between both average estimations of ETo (r). Results indicate a significant improvement in the ETo estimation at daily intervals by means of HG_HE and a reduction in the overestimation or underestimation produced by HG without corrections in its exponent. The average SEE was lower than 1.0 mm d^-1 with respect to the method of Penman Monteith (PM).

Palavras-chave : reference evapotranspiration; Penmen Monteith; Hargreaves.

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