Secondary organic aerosol (SOA) comprises a major fraction of atmospheric submicron particulate matter, which is crucial for global climate change and human health. While biogenic volatile organic compounds (BVOCs) are naturally emitted and cannot be directly controlled, field measurements and satellite observations have shown strong correlations between biogenic SOA (BSOA) production and anthropogenic emissions. The work presented herein examined the formation of the “anthropogenically controllable BSOA”. Synergistic interactions were observed between BSOA formation and SO₂ oxidation through Criegee and peroxide chemistry under various humidity conditions. In addition, an empirical framework using bulk elemental ratios was developed to predict atmospheric organic miscibility and BSOA yield enhancements in the presence of anthropogenic pollutants (e.g., vehicle and cooking emissions).

    The second part of the presentation extends the research focus from BSOA to its atmospheric precursors. The emissions, deposition, and chemistry of BVOCs are thought to be influenced by underlying landscape heterogeneity. Unquantified intermediate-scale heterogeneity in BVOC emissions over Amazonia may be a key contributor to the observed discrepancy between measured and modeled BVOC concentrations, but in situ measurements for investigating the possibility have been lacking. The measurements presented herein quantify horizontal BVOC concentration gradients over different forest subtypes at the intermediate scale of several hundred meters. The results suggest that there are biases in both top-down estimates based on satellite or aircraft measurements and bottom-up approaches based on leaf or tower measurements. The results demonstrate how observations collected by UAV (unmanned aerial vehicle)-enabled technologies fill a missing niche among leaf-level, tower, aircraft, and satellite scales. Information at this previously unavailable scale is needed for accurate understanding and predictions related to changing forests under climate stress.