Estudo da variabilidade da precipitação pluvial e do número de dias de chuva na região Nordeste do Brasil.

Abstract

The annual and intra-annual variability of rainfall and rainy days were analyzed for northeastern region of Brazil based on 600 daily time-series with more than 30 years containing both continuous and no missing data. The coefficient of variation maps were provided for monthly, annual, dry and wet periods of the rainfall and number of rainy days. Results showed that the semi arid regions have a high coefficient of variation for both rainfall and rainy days than those located in Litoral, Agreste and Meio Norte regions. The highest values of coefficient of variation are associated to the lowest values of rainfall and rainy days. The rainfall variability in northeastern region of Brazil is smaller on rainy regions and periods than on dry regions and periods. The high variability in rainfall and rainy days are limiting features to the rainfed agriculture in semi arid environments. Also, it was applied the autocorrelation function for the annual totals of the rainfall of 4 stations for each state of northeastern region of Brazil. The correlograms of rainfall indicated that the significant trend for the limits of 95% confidence bands on some stations.