Características climatológicas da precipitação pluviométrica diária de Brasília-DF.

Abstract

This work aims at detailing climatologically daily precipitation in Brasília, Distrito Federal. This variable was adjusted to Log-Normal distribution allowing to identify the occurrence probability of each theoretical class associated with the respective magnitudes. From the time series 1981 to 2010 were classified sub-samples from 1 to 7 days of rain to check the contribution and higher occurrence of rainfall over the months. It has also established the limits of extreme events of each sub-sample and verified the most favorable season for the occurrence of these extremes by Box-plot diagram. Considering the maximum precipitation occurring in each sub-sample, were established by the Gumbel distribution, the maximum expected rainfall for return periods 10, 30, 50 and 100 years, and suggested the regression equations for each case. Using the composite fields technical were analyzed seasonally the settings average from atmosphere associated with the sub-samples of 1 to 7 days of rain for the following parameters: wind 850, 500 and 250 hPa, wind magnitude at 250 hPa, the temperature anomaly at 850 hPa, average relative humidity in the layer between 850 and 500 hPa, wind divergence at 250 hPa, longwave radiation (OLR), vertical velocity at 500 hPa, divergence of the moisture flux at 850 hPa, K index and Total Totals (TT). According to the analyzes, the meteorological systems that can be associated with these instabilities rains are Bolivian High, Frontal Systems, South Atlantic Convergence Zone.