Estimation method of grass net radiation on the determination of potential evapotranspiration

Evapotranspiration depends primarily on the local energy balance, which is the most important variable of the physical environment when it comes to irrigation scheduling, especially throughout the production formation stages that are limited by water factors. The current manuscript will verify the applicability of estimates of grass net radiation to the performance of estimation methods of potential evapotranspiration under the climatic conditions in Piracicaba, Sao Paulo, Brazil. In order to proceed to simple linear regression studies, meteorological data were monitored by an automatic weather station throughout a period of 87 days for the calculation of potential evapotranspiration, taking into account both the estimated and calculated grass net radiation values. The use of grass net radiation estimated by a model based on the local energy balance showed an excellent performance for estimating potential evapotranspiration by means of the Penman–Monteith, adjusted Priestley–Taylor, and simplified Penman approaches, along with a good agreement (R2 > 0.91) related to the potential demand values obtained with grass net radiation measured by net radiometers. Copyright © 2012 Royal Meteorological Society