Modeling reference evapotranspiration over complex terrains from minimum climatological data (original) (raw)

2007, Water Resources Research

1] This work presents methods where monthly based climate data are used to estimate reference evapotranspiration (ET 0 ). The objective was to evaluate two monthly ET 0 models (Hargreaves-Samani, HS; Droogers-Allen HS, DAHS) and compare the results with an improved model (reference evapotranspiration model for complex terrains, REMCT). HS and DAHS are both based on the monthly temperature range (DT), while REMCT replaces DT with a monthly adjusted function (reference minimum air temperature). The test area was peninsular-insular Italy, where 13 stations with sufficient data to calculate FAO-56 Penman-Monteith ET 0 were available. The three models were evaluated against FAO-56 over a validation data set of six stations, using a multiplestatistics indicator: 0 (best) I ET 1 (worst). The REMCT estimates generally compared well with the FAO-56 estimates (mean I ET = 0.029 against 0.187 and 0.255 with HS and DAHS, respectively). The three models performed similarly at low-altitude sites. REMCT was superior at sites higher than 500 m above sea level, where the ET 0 À DT relationship was distorted (e.g., by an asymmetric lapse rate between maximum and minimum air temperatures). Citation: Diodato, N., and G. Bellocchi (2007), Modeling reference evapotranspiration over complex terrains from minimum climatological data, Water Resour. Res., 43, W05444,