Insights into aging of biomass burning aerosols based on satellite observations and trajectory modelling

Aerosols from biomass burning significantly impact human health, climate and society. These particles can be both natural and human-induced sources. While wildfires are considered a natural source, seasonal burning of agricultural fields before planting is an example for anthropogenic sources. With increasing global temperatures, the frequency and intensity of wildfires are escalating. Despite their importance, our understanding of these aerosols and their accurate representation in global emission inventories remain inadequate. The current estimates of the global direct radiative forcing of these aerosols range from net cooling to net warming in climate models. This shows how little we know about these aerosols and the chemical transformation they undergo as they age when they are advected farther away from the source regions. The optical properties of these biomass burning aerosols depends on the type of vegetation that is burnt, the type of burning and the prevailing meteorological conditions. Hence, in this study, we attempt to evaluate their optical properties at the source and also, as they are transported away from their source and age.

Here, we use MODIS data to locate the fires in Africa and we chose those fires based on the percentage of area burnt and the fire intensity. A trajectory model, HYSPLIT, is run to get the trajectory of the fire plumes. These trajectories are then collocated with the CALIPSO tracks to estimate the optical properties of these aerosols as they age away from the source regions.