Eventos de Precipita??o Extrema na Regi?o do Centro de Lan?amento de Alcantara

摘要

Daily precipitation data were used to identify the Extreme Precipitation (EP) events in the Alcantara Launch Center (Centro de Lan?amento de Alcantara, CLA) region for the period from Sept-1984 to Aug-2014 (30 years). Selecting the 99th percentile (44 mm d-1) as the threshold for EP, 104 events were identified in the period. The annual cycle of the EP events frequency and exceedances was similar to the annual cycle of precipitation, with maxima (minima) in the MAM (SON) quarter. Using the peaks-over-threshold approach, the annual maximum daily precipitation (defining hydrological year as 12 months from September) could be statistically modeled as a Gumbel distribution. The 1-day precipitation with return period of 100 years would be 115 mm, which is lower than the values found in the literature for localities within the CLA region. For the March and April bimester, when the largest frequency of events occurred, the interannual variability of the frequency was correlated positively and significantly (R = +0.44) with the total precipitation, and the partial correlation with other factors (such as Ni?o 3 index, interhemispheric sea surface temperature gradient in the Atlantic and wind at 925 hPa over the CLA region) was not significant. In the bimester, the EP days differed from the others with high totals as they showed greater number of hours with rain (14 ± 4 h) and greater hourly totals (e. g., maximum hourly precipitation = 23 ± 9 mm h-1). In the bimester of a specific year, 1996, when the highest frequency of events (5 events) was found, the EP days were characterized by an intense convective activity over two large areas: one zonally oriented covering the northern coast of Brazil, and the other covering the States of Santa Catarina and Paraná.