| Summary: | The present thesis analyzes possible changes in precipitation patterns in South America caused by the decrease in the extent of ice cover on the sea in Arctic and Antarctic regions. Analyzes were done through simulations with the general circulation model SPEEDY that can describe the behavior of the atmosphere when subjected to different boundary conditions. The climate simulations performed with the SPEEDY model were global, and validations were made comparing the fields of precipitation, stream function, velocity potential and vertical motion obtained in the control simulation with CFSR/NCEP reanalysis data. Impacts on precipitation patterns were established from eight different experiments by introducing idealized ice cover reduction scenarios designed for 2050 that fed the SPEEDY model in long simulations. The most significant differences in the precipitation patterns were associated with the displacements of the Intertropical Convergence Zone observed in all the experiments performed and in the different seasons of the year. In addition, changes were observed in the position of the South Atlantic Convergence Zone in the summer, as well differences in rainfall on storms track region in the Southern Hemisphere. These changes in rainfall patterns influence the large basins of the continent, such as the Amazon Basin and the Plata basin, and the rivers located in the Southeast and Northeast regions of Brazil. A presente tese analisa as possíveis alterações nos padrões de precipitação na América do Sul provocadas pela diminuição na extensão da cobertura de gelo sobre o mar em regiões do Ártico e da Antártica. As análises foram feitas através de simulações com o modelo de circulação geral da atmosfera SPEEDY que pode descrever o comportamento da atmosfera quando sujeita a diferentes condições de contorno. As simulações do clima realizadas com o SPEEDY foram de caráter global e validações foram feitas comparando-se os campos de precipitação, da função de corrente, do potencial de velocidade e do movimento ...
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