Caracterização das tempestades elétricas na região Sudeste do Brasil

Abstract

Annually, storms that occur in the Southeast of Brazil generate several disturbances to society. The Mesoscale Convective Systems (MCS) generate material losses and human lives, through the production of flooding, falling trees, hail and lightning. The spatial distribution of lightning and the properties of these storms vary greatly within this region. However, there is still a lack in the literature on the behavior of intracloud lightning and its relationship with the properties of storms. Thus, the present work aims to characterize the occurrences of lightning between 2015 and 2021 and to evaluate the physical and electrical differences in the MCS with and without lightning between 2015 and 2017 in the Southeast region of Brazil. For this, information from the meteorological satellite Geostationary Operational Environmental Satellite (GOES-13) was used, with lightning information from the Earth Network's Total Lightning Network (ENTLN). The identification and tracking of MCS was carried out using the algorithm Forecast and Tracking the Evolution of Cloud Clusters (ForTraCC). The first stage of the work consisted in evaluating the space-time distribution of lightning. Maximum of lightning occur near the mountainous regions of São Paulo, Minas Gerais and Rio de Janeiro (IC: 80 occurrences year-1 km-2 and -CG: 18 year-1 km-2), concentrated from the period of afternoon (12:00 local time), with a maximum at 16:00 local time (47,000, 2,300 and 73 occurrences of IC, -CG and +CG), and mainly in the spring and summer (maximum values of 4011, 1025 and 35 flashes IC, -CG and +CG). The current peak shows maximums in spring and autumn (~40 kA for the +CG) and a lower amount in the winter period (~20 kA for the -CG). In the second stage, the physical and electrical differences between the MCS with and without lightning were evaluated. The main physical and electrical differences between these groups show that the MCS without lightning has a smaller area (difference of 1920 km2), duration (between 30 and 60 min), expansion rate (40 x 10-6 s-1) and higher temperatures (11.5 K difference) than MCS with lightning. The life cycle behavior of lightning shows higher occurrences moments before maturation (maximum of IC: 116, -CG: 21 and +CG: 0.75 occurrences 30 min-1). These analyses are important to improve the predictability of these storms and consequently the decision-making, providing the minimization of damages linked to the harmful effects of these storms.