The Atmospheric Circulation and the Major Drought and Flood of 1983 in Brazil

Abstract

Synoptic analysis of the atmospheric circulation associated with a large scale drought in Northeast Brazil (Nordeste) and a widespread flood in Iguacu/Parana river regions (Southern Brazil) in April 1983 are conducted. The rainfall in Northern Nordeste (north of 10°S) are concentrated in March–May. Hence, the 850 mb and 150 mb atmospheric circulation over Brazil in April 1983 were compared to that of April 1974, which was a wet month in Northern Nordeste. In addition, a brief historical survey of the drought in Northern Nordeste and its relationship to the El Nino-Southern Oscillation (ENSO) events was conducted. It was shown that the two extreme climatological events in 1983 were associated with strong South Atlantic subtropical high at the 850 mb level which caused increased subsidence and decreased rainfall in Northern Nordeste. The atmospheric circulation around this anticyclone transported water vapor from the Atlantic Ocean toward the polar frontal zone in Southern Brazil. A brief historical survey of the drought in Northern Nordeste showed that the drought years are often observed in the ENSO event year or a year after an ENSO event. A 1983 drought was observed toward the end of a major ENSO event in 1982–1983. © 1985, The Association of Japanese Geographers. All rights reserved.