Hourly reference evapotranspiration by Moretti-Jerszurki-Silva method using data from alternative station/Estimativa da evapotranspiracao de referencia horaria pelo metodo Moretti-Jerszurki-Silva usando dados de estacao alternativa

HIGHLIGHTS: Moretti-Jerszurki-Silva (MJS) models can estimate the hourly ETo. Atmospheric water potential and solar radiation at the top of the atmosphere allows a reliable estimate of the hourly ETo. The hourly ETo estimation over the hours of the day can be satisfactorily performed using alternative methods. Reliable measures of climate variables and the availability of alternative and safe methods are fundamental in estimating reference evapotranspiration (ETo) under unfavorable technical and financial conditions. The objective of this study was to evaluate the performance of the reference evapotranspiration estimation, in hourly periodicity, using the Moretti-Jerszurki-Silva models ([ETo.sub.MJS([PSI]air)]; [ETo.sub.MJS([PSI]air;Ra)]), which considers air temperature (T) and relative air humidity (RH) data measured in an alternative station. The calibration and validation of the alternative station measurements were performed using data from automatic meteorological stations in Curitiba in Parana (climate type Cfb) and Santa Rita de Cassia in Bahia (climate type Aw), Brazil. The use of the alternative station for hourly measurements of air temperature and relative air humidity in the analyzed climate types and locations were promising. The Moretti-Jerszurki-Silva models were robust in the analyzed locations, indicating satisfactory performance for the hourly periodicity. The Moretti-Jerszurki-Silva method that uses atmospheric water potential and solar radiation ([ETo.sub.MJS([PSI]air;Ra)]) provided better adjustments and estimates of the hourly reference evapotranspiration, as opposed to the standard Penman-Monteith model. Key words: water relations, water requirements, alternative methods, weather stations Medidas confiaveis de variaveis climaticas e a disponibilidade de metodos alternatives seguros sao fundamentals para estimar a evapotranspiracao de referenda (ETo) em condicoes tecnicas e financeiras desfavoraveis. Objetivou-se no presente estudo avaliar o desempenho da estimativa da evapotranspiracao de referenda, na periodicidade horaria, com os modelos Moretti-Jerszurki-Silva ([ETo.sub.MJS([PSI]air)]; [ETo.sub.MJS([PSI]air;Ra)]), utilizando dados de temperatura (T) e umidade relativa (UR) do ar, medidos em estacao alternativa. A calibracao e validacao das leituras da estacao alternativa foram realizadas com dados de estacoes meteorologicas automaticas de Curitiba no Parana (tipo climatico Cfb), e Santa Rita de Cassia na Bahia (tipo climatico Aw)