Impacts of biomass burning smoke in clouds and rainfall in southern Brazil

Biomass burning aerosols can spread over vast areas of South America. Recent findings indicate that the presence of these types of aerosols tend to affect cloud formation and rainfall. This research aimed to study the impacts of smoke aerosol emissions in southern Brazil, due to prolonged drought and dry events in the region. Initially, data on aerosol optical depth, precipitation, and clouds were collected to assess the influence of aerosols on the evolution of these meteorological processes. The data analysis focused on the study of the dry season in southern South America, which spans August, September, and October through the years of 2002 to 2022. Results obtained using the HYSPLIT model showed that black carbon transport during the study period originates from regions such as Paraguay, the Brazilian Midwest, and southern Amazonia. Monthly data analysis for the period of 2002 to 2022 revealed a negative Pearson correlation for August-September-October, respectively: -0.44, -0.35 and -0.37 between the aerosol optical depth (AOD) particles and precipitation; and -0.27, -0.39 and -0.22 between AOD and cloud formation. For Spearman correlations were obtained: -0.43, -0.29 and -0.21 between the aerosol optical depth (AOD) particles and precipitation; and -0.11, -0.26 and -0.23 between AOD and cloud formation. Although the results indicate a weak negative correlation, these results point to positive feedback where aerosols can negatively affect the formation of clouds and rain, causing dry periods with a greater probability of fires and smoke.