Análise mensal da evapotranspiração para o Rio Grande do Sul usando o modelo complementar de Morton

Abstract

In the present study the Complementary Model of Morton was used to estimate the monthly taxes of potential and actual evapotranspiration of area of different places of Rio Grande do Sul, in the period from 1969 to 1998. The analysis was made starting from the space distribution of the variables in the whole of the State, when relating the pluvial precipitation, temperature of the air and heatstroke with the available energy, real evapotranspiration of area and potential. It was observed that in a large part of the State, ETR was high in the Coast, in the south of the Medium Plateau, and in the Northwest of the State during the whole year. It is low in the Northeast of the State. ETP was already also shown high in the half West of the State, standing out the North in the months of May to July. As the Model of Morton was used to generate the actual evapotranspiration of area and potential, and in the intermediate months of the year (May to August) the precipitation was higher, ETR didn't answer to that increase, being well below ETP. It was concluded that in that period of the year the readiness of energy was the factor most important in the evapotranspiration process for the State of Rio Grande do Sul, thus, the Model is not adapted to evaluate that excessive increase of precipitation.