Padrões climáticos associados à periodicidade de eventos extremos de precipitação no Estado do Maranhão.

Abstract

The state of Maranhão is located in a transition zone receiving climatic influences the semiarid northeast, the hot and humid Amazon and plateaus of central Brazil, giving the State peculiar characteristics. However, it has well-defined climatic conditions, with normally dry winter and rains prevalent in the fall and summer. Considering the importance of detecting and need rain anomalies in the state, this study aims to define spatial patterns and temporal correlations of precipitation and the Standardized Precipitation Index - SPI in 3 time scales, 6 and 12 months. For this, we used the method of factor analysis in principal components. From the common factors selected met the homogeneous regions in different scales of the SPI. For each homogeneous region of SPI were characterized dry and rainy events, as well as quantified the frequency of the same in the state of Maranhão. Also found the ratio of dry and wet events with the possible weather systems operating in the region. The results showed the highest incidence of dry occurred in the South and the highest rainfall were recorded in the northern state of Maranhão. In seasonal scale SPI the state was divided into four homogeneous regions (RH), The results showed the highest incidence of dry occurred in the South and the highest rainfall were recorded in the northern state of Maranhão. In seasonal scale SPI the state was divided into four homogeneous regions (RH) the northern and northwestern regions showed good correlation with SST anomalies in the Pacific and the Atlantic Ocean South. In the six months scale met five HR the SPI, with similar pattern the average monthly rainfall, confirming the state has two stations in well defined year. For the SPI-12, the state was divided into two regions (north-south). The longer periods of dry events (rainy) corresponded to periods of strong event El Niño (La Nina). It was also observed, the rains in the region are afforded mostly by the performance of various weather systems, such as, the Intertropical Convergence Zone, cyclonic vortices of High levels, South Atlantic Convergence Zone and Frontal Systems.