ABSTRACT
The Characteristics of atmospheric variability in the continental tropics between 20°N and 35°S during warm and cold phases of the southern oscillation are investigated. The analyses are based on Xie-Arkin and reanalysis data. Composites of rainfall anomalies during warm and cold phases of the southern oscillation are constructed. During the warm ENSO years, the composites exhibit below normal rainfall over southern Africa and northern South America. The analysis of the 500 mb height anomaly shows that an anomalous anticyclonic circulation develops over southern Africa and the adjacent Atlantic Ocean, and along the coasts of southern Brazil, Uruguay, and Argentina. An anomalous anticyclone also tends to dominate the central Indian Ocean. Further to the south over the Atlantic and the Indian Ocean, an anomalous cyclonic circulation extends from 100°E to 30°W. The analysis of the 200 mb velocity potential indicates positive anomalies centered over southern Africa and northern Brazil suggesting upper level confluence and subsidence. The analysis of the 200 mb stream function shows that positive anomalies are predominant over the Southern Hemisphere during the warm phase of ENSO. A reverse in the circulation patterns during the cold phase of the SO is evident. Results from several reanalysis data sets and for different tropical regions are discussed. The effects of the 1997-98 EL Ni o on tropical South American and African rainfall are also presented