A Performance Evaluation of Nine Potential Evapotranspiration Methods Against the FAO-56 Penman–Monteith Benchmark at the Broadleaf Forest of Taxiarchis in Northern Greece

Potential evapotranspiration (PET) is a critical component of the water cycle, driving plants’ growth and survival. This study focused on estimating the daily potential evapotranspiration (PET) in a forest site in Northern Greece and assessing the performance of nine empirical PET estimation methods. These methods, categorized into mass-transfer, temperature-based, and radiation-based models, were compared against the widely used FAO-56 Penman–Monteith benchmark. The results highlight significant seasonal and monthly variations in vegetation water requirements. Among the methods tested, radiation-based models, particularly the Makkink equation, outperformed the others, followed by the Turc and Priestley–Taylor models. Temperature-based methods showed moderate performance and could serve as viable alternatives in forests with limited data availability, though local calibration is advisable.