Dinâmica do comportamento das queimadas na região da Amazônia Legal: uma abordagem climatológica e de produtos de sensoriamento remoto

Abstract

The Amazon rainforest, one of the most important ecosystems on the planet, covers a vast area of the Amazon basin. This region contains more than half of the world's tropical forests and plays a crucial role in mitigating global warming as a massive carbon reservoir. Historically, fires in the Amazon have been associated with drought events and human activities. In the most contemporary scenario, the interconnection between wildfires, deforestation, and drought periods has resulted in alarming increases, especially in the year 2020. Consequently, the long-term impacts of these fires on vegetation and soil still need to be better understood. In the face of challenges arising from anthropogenic activities, such as increased deforestation and extreme climatic events, the Legal Amazon urgently needs to implement effective conservation strategies. In this regard, the objective of this research is to analyze and contribute to the understanding of fire behavior in the Legal Amazon region between the periods of 2012 and 2023. To achieve this, we utilized the Fire Radiative Power (FRP) product with a spatial resolution of 375m from the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard the National Oceanic and Atmospheric Administration (NOAA) satellites NOAA-20 and Suomi National Polar-orbiting Partnership (SNPP), which are sun-synchronous. In the analysis of fires and climate, meteorological reanalysis variables from ERA5 with a horizontal resolution of 0.25° were used. The results of this research highlight distinct patterns between the state of Roraima and the other states of the Legal Amazon. FRP exhibited greater variability between July and December, except in Roraima, where the highest variability occurred from January to June. The largest peaks in burned area during the months of July to December in the analyzed microregions occurred from 2020 onwards, registering approximately 8 million hectares in Altamira (PA), followed by São Félix do Xingu (PA) with around 7 million hectares, Apuí (AM) with approximately 5 million hectares, and Aripuanã (AM) with about 2 million hectares. During the months of January to June, the peak of burned area occurred in 2019 in most municipalities, with approximately 500.000 hectares in Caracaraí (RR), 300.000 hectares in Mucajaí (RR), and 100.000 hectares in Alto Alegre (RR). Regarding fire duration, the states of Pará, Amazonas, Acre, and Mato Grosso exhibited the highest intensities during the months of July to December, mainly from 2017 onwards, occurring during El Niño years (2019), as well as in La Niña years, such as 2017, 2021, and 2022. The frequency of fire_id records throughout the study period revealed that the state of Pará had the highest incidence, with the municipality of São Félix do Xingu recording a frequency of 12,000, while Altamira, Itaituba, and northern Rondônia each had a frequency of 8.000. Additionally, in these municipalities, most occurrences were attributed to anthropogenic causes. The analysis of meteorological variables and the monthly average NDVI from July to December 2019 indicates that the vegetation area in the analyzed microregions suffered a significant decline, with NDVI decreasing from approximately 0.46 in August to 0.30 in December. This decline was associated with a temperature anomaly of approximately -5°C from July to September, a lower relative humidity anomaly (~ -17%), mainly in August, with recorded wind speeds of approximately 4 m/s and the most significant wind anomaly in the state of Pará (3 m/s), particularly in July and August. Although relative humidity increased from October onwards, favoring a slight vegetation recovery, NDVI continued to decline, reflecting the persistent effects of climate stress throughout the analyzed period. In the state of Roraima, during the months of January to June 2019, NDVI recorded average values of approximately 0.28 in April, 0.26 in May, and 0.32 in June, indicating an initial decline followed by a recovery in the last month. This was associated with high temperatures, mainly from January to April, with the most intense temperature anomaly occurring in March (-5°C), the most intense wind anomaly in January and February (~1.8 - 3.6), and low relative humidity in the first months of the year (~45% - 30%), particularly in March.