Extreme Rainfall Events in Northeast Brazil and Atmospheric Characteristics

Abstract This study investigated the means characteristics atmospherics associated with extreme precipitation events with until three-day delay before the occurrence of such extremes. The extreme events were chose when in most grid points on the Northeast of Brazil (2° S-12° S and 45° W-37° W), daily rainfall was equal or more than 50 mm. Daily data precipitation were of a set of rainfall stations distributed over NEB, from the observational networks of the National Institute of Meteorology, National Water Agency and Meteorology and Water Resources Regional's Centers, covering the period 1974-2003. These data were interpolated spatially using the technique of Inverse Square of the distance to a regular grid with a resolution of 1° in latitude and longitude (about 111 km). For analyzes of atmospheric features were used in atmospheric variables reanalysis data as southern zonal wind, air temperature, relative humidity and other reanalysis of NCEP-NOAA from the surface until 200 mb. The most significant results showed that three days before of the precipitation events considered extreme, there is a cold air incursion into the central area of the NEB, intensifying a day before of the events days, with lower anomalies below −4 °C, which do not appear to events considered of low rainfall over the region.