Resumen

RIBEIRO DA, Antonio Cunha; VOLPE ALBERTO, Clovis  y  ESCOBEDO JOAO, Francisco. Estimating reference evapotranspiration by Penman-Monteith method (FAO-56) with measured net radiation for different sensors¹. Agronomía Trop. [online]. 2008, vol.58, n.1, pp.81-84. ISSN 0002-192X.

It was compared estimates of reference evapotranspiration (ETo) by Penman-Monteith method (FAO-56) utilizing net radiation (Rn) data obtained in net radiometer NR-Lite (Kipp and Zonen), Q-7.1 (REBS) and CNR1 (Kipp and Zonen), in the period from 09/28 to 11/22/2001 in Botucatu, UNESP, SP. The estimates of ETo were verified and compared through the statistical indicators: determination coefficient (R2) and agreement index (d). With the constants of original calibration the sensor NR-Lite and Q-7.1 underestimated in a significant way in the daylight periods and nocturnal, and consequently ETo was also underestimated. With the use of one new calibration constant the sensor NR-Lite and Q-7.1 started to overestimates of way no significant, in relation to sensor CNR1 (reference), could be used like this for measures of energy balance with accuracy. The estimate of daily ETo for the equation of Penman-Monteith (FAO-56) obtained starting from Rn measured by sensor Q-7.1 it went to that more he approached of the found values of ETo in function of Rn measured by the CNR1.

Palabras clave : Evapotranspiración; balance de energía; radiación neta.