Estudo de precipitação no Estado da Paraíba: regimes pluviais e caracterização de anos secos e chuvosos.

Abstract

Total daily rainfall data from 19^0 to 1977 at 32 stations in the state of Paraíba, were analized and four distinct rainfall regimes were identified. The maximum and minimum numbers of expected rainy days in the rainiest quarter of the year in each station, at a 80% probability level were determined employing the "quintis" technique. The different years are classified as "dry", "normal" and "rainy", based on the mean and standard deviation of the total annual rainfall. The characteristics of the "dry" and "rainy" years were determined by using those rainfall informations. A method is proposed to evaluate, at the beginning of the year, if a particular year will be "dry or normal" (SL) or "normal or rainy" (CL), by comparing the total rainfall observed, against a limiting value which corresponds to a reference month (Mi) in each station. Values of L and Mi, as well as the probability of occurence of SL and CL years, associated to the possible situations (P <_ L and P > L in the Mi month) are included. Finally, a method is presented where the "quintis" technique is also applied, aiming to determine, at a 80% probability level, the expected amounts of maximum and minimum rainfall that might occur after the "Saint Joseph's day" ("Dia de São José" — 19th of March), as a function of the total rainfall actually observed till that day.