Análise sinótica dos eventos com trovoadas para o estado de Alagoas dentre o período de 15 anos (1998-2012)

Abstract

The Brazilian state of Alagoas is extremely affected by a sort of different kind of adverse phenomenon, one of them is what we called thunderstorm. The prediction of this adverse phenomenon carries a lot of interest from all the segments of the society. The study of the adverse phenomenon synoptic systems was done is this paper. For this purpose, data from the Airspace Control Department (DECEA) and also data from the Tropical Rainfall Measuring Mission (TRMM) satellite was used to find out the number of incidence of the thunderstorm. It also used reanalysis data from the National Centers for Environmental Prediction (NCEP); GOES 8 satellite, owned by the Centro de Previsão de Tempo de Estudos Climáticos (CPTEC) and GOES 12 by the National Climatic Data Center (NCDC). A large number of synoptic maps were done using the Grid Analysis and Display System (GrADS) software. The synoptic study was done for all the 212 cases found in the last 15 years, between 1998 and 2012. The amount of thunderstorm in the year of 2008 was the highest of all this period, with 21 cases, on the other hand, the year of 2012 show the fewer number of cases, with only 04. In this study, was observed that January, February and March, were the months with more incidence of this phenomenon. For the identification and eventual analysis of the synoptic system, were used streamlines images, in all the atmosphere levels, with satellite images. In this study, was identified at least five synoptic systems associated with thunderstorm in Alagoas: Trough at Upper Levels, Intertropical Convergence Zone (ITCZ), Upper Tropospheric Cyclone Vortex (UTCV) and Middle Tropospheric Cyclone Vortex (MTCV). In fact, UTCV and Trough at Upper Levels, were the systems with more incidence of thunderstorm. The focus of this paper was the location of the thunder in each synoptic system. It was demonstrated that the Rearward of the Trough at the Upper Levels was the area with more incidence. Analyzing the UTCV, was found the thunderstorm were more common in the North, Northwest and Northeast. Nevertheless, were presented is this paper, examples of thunderstorm in each one of the synoptic systems. The instability indices analysis also showed to be a relevant topic, because it demonstrated the adverse phenomenon intensity in each event. For the Trough at the Upper Levels, the CAPE+ and LI indices have the highest medium values (1374,4 J∙Kg⁻¹ e -4,6), UTCV (1319,6 J∙Kg⁻¹ e -4,5) and ITCZ (1479,1 J∙Kg⁻¹ e -5,2). However, Front Zone events (1030,8 J∙Kg⁻¹ e -3,8) and MTCV (409,5 J∙Kg⁻¹ e -2,0) presents the lowers averages of thunderstorm. All the data provide from this work will be used to make an upgrade in the climatological and synoptic series for the thunderstorm prediction in Alagoas.