Avaliação dos relâmpagos totais na bacia do Rio São Francisco com o uso do sensoriamento remoto

Abstract

Brazil holds the title of being the country with the highest incidence of lightning in the world, registering approximately 77.8 million occurrences annually. The annual number of lightning victims in the country is about 0.8 per one million inhabitants. In the São Francisco Watershed, an average of 7,36 𝑓𝑙𝑎𝑠ℎ 𝑘𝑚−2𝑎𝑛𝑜−1. A notable example is the city of São Desiderio in Bahia, where the incidence is 39,9 𝑓𝑙𝑎𝑠ℎ 𝑘𝑚−2𝑎𝑛𝑜−1, making this location one of the most intense hotspots in Brazil. Given this scenario, the central objective of this monograph is to conduct a detailed analysis of the temporal and spatial distribution of lightning in the São Francisco River Watershed. Additionally, the relationship of these patterns with the topography of the studied region was evaluated. To achieve these objectives, lightning data from the LIS sensor from 1998 to 2013, Digital Elevation Model data provided by ASTER, and precipitation data from WorldClim obtained through the MODIS satellite platform over a 30-year observation period were used. The analysis of total lightning rate density data was incorporated into the k-means clustering methodology, aiming to identify pixels with similar characteristics. The results obtained allowed observing that the topography influences the behavior of these phenomena in the region during the months of April to September. Atmospheric systems act as intensifiers of lightning, especially during the summer when higher values are observed in the late afternoon and early evening, reaching values like 37 𝑓𝑙𝑎𝑠ℎ 𝑘𝑚−2ℎ𝑜𝑟𝑎−110−3, and lower values during the morning.