Estimation of solar radiation and its application to crop simulation models in Greece

摘要: Lack of data on site-specific daily solar radiation (Rg) is a significant impediment for most crop modeling applications. For this reason, 5 methods estimating Rg were tested: the Angstrom-Prescott equation (AP), Supit - van Kappel formula (SK) and 3 temperature-based methods: Campbell-Donatelli model, Hargreaves equation, piecewise multiple linear regres- sions with breakpoint (PLR). To overcome lack long continuous time series mea- surements at sites, satellite-derived from HelioClim-1 database tested against observations 2 stations, then interpolated 12 additional stations. When sunshine duration available, AP was best, because it (1) produced intercepts slopes closest to zero unity, respectively (2) had lowest relative RMSE (9 18.6%). cloud cover maximum minimum temperatures SK equally effective as in assessment metrics. only site maxi- mum temperatures, PLR approach breakpoint, which reflects value response changes function extraterrestrial RA diurnal temperature range, performed best. The mean <3.7% higher than that AP. provided suitable simulation measured CERES-Wheat while among smallest yield errors. Future validation efforts should explore validity model other regions under regimes greater availability