Floods in Brazil

In this work the higher flood events occurred in Brazil from 1979 to 2010 were determined in order to describe the atmospheric circulation patterns associated with them. An analysis was hold in the 23 extreme ones, according to the season (summer/winter) and the region where the event occurred. The main causes identified were the El Nino episodes, Madden-Julian Oscillation, ITCZ and SACZ, besides smaller scales systems. The events that were not related with these causes need further investigation. Introduction The South America lands are distributed along different latitudes, from above the equator to higher than 55oS. The consequence is a vast diversity of climates due the presence of different atmospheric systems (Reboita et al., 2010). Brazil, with a large extension, shows it clearly as its lands cross low and high latitudes. It has numerous environments in each part of the country, leading to different weather conditions and precipitation patterns. As a result the frequency of flood events is fairly high, since they are distributed along the regions and also year round. According to Reboita et al. (2010), these patterns can be classified in 8 different groups along South America, considering the graphs of monthly precipitation. Only the ones including Brazilian lands are going to be addressed in this work. Table 1 shows the patterns in each part of Brazil as well as the mechanisms involved in each one of them, as shown by Reboita et al. Region Features of Annual Precipitation Cycle Atmospheric Systems Acting South of Brazil Precipitation mostly homogeneous during the year with high rainfall totals. Frontal systems and cyclones from the Pacific Ocean; subtropical CVHL; IL; subtropical MCCs; atmospheric blocking; sea breeze; SACZ; SASA; eastern Andes LLJ. Northwest to Southeast of Brazil Maximum totals in summer and minimum in winter. Trade winds; eastern Andes LLJ; SASA; convection due surface heating; BH; ITCZ; sea breeze; IL; tropical MCC; frontal systems; subtropical CVHL; cyclones.