Chuva extrema na estação seca de Alagoas

Abstract

The complex climatic characteristics of Alagoas generate a considerable variation in the spatial distribution of precipitation. In this context, researching the atmospheric systems linked to precipitation becomes crucial, given their association with disasters that result in impacts on civil structures and even human losses. This work aims to identify extreme rainfall events, using the 95th percentile, occurring during the dry season in Alagoas, which takes place between October and February. The 95th percentile was applied to precipitation data provided by the State Secretariat for the Environment and Water Resources (Semarh) between the years 2010 and 2022. In total, 344 cases with volumes exceeding 26.2 mm in 24 hours were found. Due to the large number of cases and the absence of concurrent cases in the regions, the case with the highest precipitation was chosen for each region to be presented in detail. The case of the highest precipitation (181 mm) that occurred in Igreja Nova was also presented in detail. Synoptic analyses of the chosen cases were performed using the ERA-5 reanalysis provided by the global numerical model The European Centre for Medium-Range Weather Forecasts (ECMWF), aiming to identify the synoptic systems associated with extreme events. Satellite images, collected from the Infrared, Enhanced Infrared, and Water Vapor channels, were obtained from the Center for Weather Forecasting and Climate Studies (CPTEC). The satellites used were GOES13, GOES-16, Meteosat-8, and Meteosat-9. The influence of the South Atlantic Convergence Zone (SACZ) and the Frontal Systems (FS) were responsible for the highest 24-hour precipitation values in all regions of the state of Alagoas. The Cyclonic Vortex of High Levels (CVHL) was also responsible for a significant portion of extreme precipitations in the state of Alagoas, with volumes exceeding 90 mm in 24 hours.