Recent development and universality evaluation of ET₀ calculation formulas

This article, through summarizing the progresses in the evapotranspiration (ET₀) methods research, analyzes representative ET₀ computation methods emphasized on three periods of the world: modificative Penman (MP), Penman-Monteith (PM) and standard ASCE-PM.We take 20th century 90's last stages and 21th century initial period's world newest 19 experimental achievements with lysimeter's actual value rating ET₀ value as the foundations, analyzing general usage of the ET₀ computational method regarding the different climatic conditions Although the effect of PM method application is desirable in many areas, many local effects are still unsatisfactory; the method MP and so on are more suitable in part of areas; the PM and MP method are not popular, the special attention must be paid to the standard ASCE PM method.In brief, these kinds of half theory (semi-empirical) methods only suit in certain areas By comparison of MP and PM method, we can't simply evalu ate which kind of method is superior or which kind of method calculates the ET₀ value big (or value is small), and we should consider different geography, the climatic conditions and lysimeter experimental result.In the article, there is also corresponding suggestion for the research in the future, which is helpful to the thorough research of ET₀ method discipline.