Alternative reference evapotranspiration methods for the main climate types of the state of Paraná, Brazil

Abstract: The objective of this work was to define the best alternative methods for estimating the reference evapotranspiration (ETo) in the main climatic types (Cfa and Cfb) of the state of Paraná, Brazil. The methods tested were Budyko, Camargo, Hargreaves-Samani, Linacre, and Thornthwaite, which were compared to the ETo calculated with the Penman-Monteith ASCE (EToPM) method, between 1986 and 2015, in eight meteorological stations. The performance of the alternative methods was obtained from the coefficient of determination (R2), index “d” of agreement, index “c” of performance, and root mean square error (RMSE). The Hargreaves-Samani method has a better performance in estimating the ETo for the main climatic types in the state of Paraná. The Camargo method allows smaller errors between the standard values of ETo, obtained with the Penman-Monteith method, and the estimated values. The methods of Thornthwaite, Linacre, and Budyko are not adequate to estimate the ETo in any climatic type of the state of Paraná, Brazil.

摘要：本研究旨在为巴西巴拉那州主要气候类型（Cfa与Cfb）下的参考蒸散量（reference evapotranspiration, ETo）估算确定最优替代方法。本次测试的方法包括Budyko、Camargo、Hargreaves-Samani、Linacre及Thornthwaite，将其与采用Penman-Monteith ASCE法计算得到的参考蒸散量（EToPM）进行对比，研究时段为1986年至2015年，覆盖8个气象站点。替代方法的性能通过决定系数（coefficient of determination, R²）、一致性指数d、性能指数c以及均方根误差（root mean square error, RMSE）进行评价。研究结果表明，Hargreaves-Samani法在巴拉那州主要气候类型的ETo估算中表现最佳。Camargo法所得估算值与Penman-Monteith法得到的标准ETo值之间的误差更小。而Thornthwaite、Linacre与Budyko三种方法，均不适用于巴西巴拉那州任意气候类型下的ETo估算。