Papel de Deformacao Horizontal NA Frontogenese Nal Regiao Sul Brasileira (Paper on Horizontal Deformation in the Frontogenesis in South Brazil)

摘要

A climatological study of the frontogenetic and frontolytic effects of the horizontal deformation and divergence fields in the lower troposphere over the part of the globe enclosed between 45 N and 45 S is made. Four bands of frontogenesis, aligned northwest to southeast, are clearly seen, and one of them agrees closely with the South Pacific Convergence Zone. The frontogenetic function over the central and southern Argentina is strongest in summer (January), which is in contrast to the Northern Hemispheric situation. Over South America, a northwest to southeast oriented line passing through the state of Rio de Janeiro divides the regions of frontogenesis to the southwest and frontolysis to the northeast. A case study of the frontogenesis which occured in the period 28 to 31 July 1980 over South Brazil is presented. It shows clearly the importance of the horizontal deformation field in the formation, intensification, orientation and movement of the front. In the formative stage, strong warm advection ahead of the front is observed in the lower middle troposphere and strong cold advection behind the front in the surface layers.