Simulation of Biomass Burning Events and Their Atmospheric Effects: A Study with WRF-Chem

In the Southern Hemisphere, regions in South America are recognized as significant sources of carbonaceous aerosols, which are produced by biomass burning. This type of burning typically occurs during the winter months, predominantly in the region known as the "Deforestation Arc," often associated with the expansion of agricultural and livestock production areas in Brazil.  Given the limited number of observations in this region, numerical modeling becomes essential for analyzing and accurately representing biomass burning events. In this context, the purpose of this study is to discretize the atmospheric behavior during fire events across South America by utilizing the Weather Research and Forecasting with Chemistry (WRF-Chem) model, thereby assessing the impact of these carbonaceous aerosols on cloud microphysics throughout the region. 

For this study, WRF-Chem version 4.3.1 was employed. The simulation began on September 28, 2007, and ended on October 3, 2007, using ERA5 fields to provide the initial and boundary conditions with a spatial resolution of 0.25°. The domain covered the South American region. Two simulations were conducted: the first, referred to as the control simulation (CTRL), had the coupling between aerosols, radiation, and cloud microphysics turned off, while the second, the fully coupled simulation (CPL), enabled both couplings. This approach facilitates a subsequent analysis to distinguish the role of aerosols on radiative properties and quantify the effects of coupling. For the analysis, precipitation fields, radiation components, and hydrometeor composition were evaluated in both simulations. This approach provides insights into the influence of biomass-burning aerosols on atmospheric processes and their role in modifying cloud microphysics and radiative balance.