Abstract: The Cerrado biome is the second largest biome in South America and the majority of its territory represents the largest savanna in the world. It plays a vital role in the Brazilian ecosystem, sheltering a rich biodiversity and contributing significantly to the stabalization of climate and water availability. The cerrado biome has faced challenges due to climate change in the last decade, evidenced by extreme events such as prolonged heat waves, periods of drought and increased risk of fires. Given this context, this work aims to analyze the impact of compound drought and heat wave events on wildfires in the Brazilian Cerrado biome from 2012 to 2022. Thus, monthly and annual analyses of heat waves (HW), Fire Radiative Power (FRP) and drought were carried out for 164 stations located in the Brazilian Cerrado biome. The maximum and minimum temperature and rainfall were observed data collected from the National Meteorological Institute (INMET), and the FRP variable was obtained from the Visible Infrared Imaging Radiometer Suite – VIIRS satellite (S-NPP). This study adopted the CTX90 pct and CTN90 pct calculations, which define a heatwave as a period of at least three consecutive days with maximum and minimum temperatures above the 90th percentile. To characterize drought events, we used the Standardized Precipitation Index (SPI) over 6 and 12 month periods. In general, the results from the SPI-6 and SPI-12 analyses showed values throughout the series that ranged from moderately humid to extremely humid, with the most intense values from January to March. Negative values indicated the presence of mild drought, with more intense values from July to September. These periods coincided with more intense periods of heat waves, resulting in a higher frequency of these events, especially in September and October, which obtained 27 (for the CTX90 index) and 22 (for the CTN90 index) heat waves in Formoso do Araguaia (TO) e Dianópolis (TO), respectively. These periods in which drought and heatwave events occurred had a direct impact on the FRP and Fire Radiative Energy (FRE) variables, which showed higher intensities in these simultaneous periods. In addition, the longest heat wave durations were present in the months considered wet and dry by the SPI analysis, with a maximum duration of 31 days for both indices, indicating a relationship between the intensity of these climatic events and the variables associated with fires in the Cerrado biome. The results especially highlight the urgent importance of understanding the joint dynamics of drought and heat waves in order to better assess and prevent fires in this region.

Keywords: Compound events, fires, heatwaves, droughts, Cerrado bioma.