The goal of this study is to analyze the spatial and temporal distribution of the components of the modified reference evapotranspiration (ETr) in Brazil. The temporal variability is investigated through the technique of harmonic analysis for two periods: present day (1980-2000) and future climate (2080-2100) based on A2 scenario of the Intergovernmental Panel on Climate Change. The method applied to evaluate the ETr was the Penman-Monteith standardized by FAO. The simulations were conducted with the regional climate model (MM5) coupled to a potential vegetation model (MVP). The results show that the aerodynamic term is dominated by the annual cycle in the Amazon region and southern Brazil, while in the southeastern the semiannual cycle has greater prominence. The largest variations in the ETr amplitude have been identified in the semi-arid part of the northeastern and in the far south of Brazil. Changes in the ETr due to global warming were highest in the central region of Brazil and the Amazon. Moreover, it has been noted that under global warming conditions changes of the aerodynamic term become more important than the variations of the radiative term in producing the ETr anomalous pattern.
Penman-Monteith; climate changes; numerical modelling
