Frequência Mensal e Sazonal da Participação de Sistemas Atmosféricos no Verão do Rio Grande do Sul: Análise sobre Três Casos Típicos (1986/1987, 1997/1998 e 2004/2005)

Abstract

The and of the time succession, that became one of the mainresearch field in Geographical Climatology, allows the accomplishment ofa seasonal balance of the involvement of the atmospheric systems, that canbe one of the ways of classifying the climate of an area. Thus, the generalobjective of this research was to accomplish the monthly and seasonal balanceof the contribution of the atmospheric systems during the summerof Rio Grande do Sul in three typical examples: regular, rainiest and lessrainy summer. A theoretical framework was accomplished in a regionalatmospheric dynamic. The climatic data of Santa Maria/RS’s MeteorologicalStation were analyzed, from the summers of 1969 to 2005, being selectedthe summer of 1986/1987, 1997/1998 and 2004/2005 as representatives ofa regular, rainiest and less rainy summer. The technique of the rhythmicanalysis of the period was applied proposed together with satellite imagesand synoptic maps, in which it was possible to identify the activeatmospheric systems in the three representative cases. It was calculatedthe frequency of atmospheric systems participation of each month and theseason analyzed. In the regular summer, the majority of the time, the OldPolar Mass dominated, except in December. Among the perturbed currents,the largest frequency in the State is the Polar Fronts. In the rainiest summerthe largest performance of the extratropical origin systems that gave to thestation high pluviometric indices was also observed. In the less rainy summerthe air masses of polar origin disqualified that was dominated almost duringall the station. Among the disturbed currents, the frontal passages are theones that dominate. Thus, it was proved, once again, the predominance ofthe extratropical atmospheric systems upon intertropical origin in RioGrande do Sul, even during the summer.