Regimes pluviais, estação chuvosa e probabilidade de veranicos no Estado do Ceará.

Abstract

The objective of research is to contribute with the technical information which is necessary for the solution of the socio-economic problem developed due to the climatic adversities in the Ceará State. A rainfall regionalization method is proposed and is applied to the monthly precipitation data of 175 localities of the Ceará State. It resulted in the identification of three homogeneous precipitation groups, group 1 being predominantly semi-arid. Such groups were compared with the seven climatic regions recognized by Fundação Cearense de Meteorologia e Recursos Hídricos (FUNCEME) and is verified that the method is capable of identifying the Ibiapaba and Cariri regions, as well as the area formed by the East central and West central regions and the area formed by the coastal regions of North and South. The method is also applied to the data of the Paraíba State and the regions obtained are consistent with those obtained by Bastos (1986), Silva (1989) and Braga & Silva (1990). Also identified is the rainy season (EC) for all the localities of the Ceará State utilizing the method Frère & Popov (1979). It is also verified that 143 (81.71%) out of the 175 localities, the EC occurs from January to May and in 69 (65.71%) of the 105 localities of group 1, the rainy season occurs from February to May. Finally, the daily precipitation data are used to verify the probability of occurrence of the dry spells in the three ten-day poriods (days 1 to 10, 11 to 20 and 21 to the last day of the month) for the months of January to June and for all the 105 locations of the group 1. And it is found that the mean probability of having a dry spell in the first, second and third 10 day-periods of the month of January is 51, 39 and 25%; in February it is 20, 18 and 21%; in March 10, 7 and 6%; in April 9, 10 and 11%; in May 25, 25 and 28%; and in June 38, 43 and 51%.