Probable monthly rainfall in the ‘Agreste’ of Pernambuco State

Abstract

Rainfall distribution and its temporal variability are relevant characteristics, mainly in the Northeast of Brazil (NEB), where rainfall is a key factor which determines the two seasons in the region: the dry season and the rainy season. Thus, rainfall has a strong influence on the agricultural activities, determining the cropping periods and affecting the crop development and harvesting. In the present work, four probability distributions for monthly time series of rainfall were analyzed for the Pesqueira town in the ‘Agreste’ region of Pernambuco, situated in the NEB, from 1920 to 2010. To verify the fitting of the probability functions to the observed frequency, non-parametric chi-squared test was applied. For the rainy season, the period from February to July, was characterized with a mean rainfall of 84.60 mm month^-1; the period from August to January was identified as the dry period presenting a mean precipitation of 46.0 mm month^-1. The Normal distribution presented the best fit for the rainy period records, representing 50% of the analyzed months.