Frontal Influences on Northeast Brazil

Surface observations for the 10-year period 1961–70 are analyzed for occurrences of fronts in North-east Brazil. Cold fronts, or their remains, are found to enter the Northeast throughout the year. The southern part of the region (interior Bahia) receives much of its precipitation in the period November-February associated with frontal systems. Coastal areas. which receive maximum rainfall during the months of May–July, experience a marked increase in rainfall associated with the approach and passage of cold fronts. Even precipitation events in the extreme northern part of the region (Ceará) sometimes appear to be associated with systems which are cold-frontal in origin. Pressure fluctuations are felt nearly simultaneously throughout the region with greatest amplitudes occurring in the south. These fluctuations are also shown to occur over a fairly broad range of longitude within tropical Brazil and may have a significant effect on the position of the equatorial trough zone over the Atlantic.