Atmospheric aerosols originate from multiple natural and anthropogenic sources, and their emission strengths depend strongly on a combination of biological, geologic, human, and meteorological factors. Once emitted into the atmosphere, they often form complex mixtures that affect the earth system on multiple spatial and temporal scales. Natural aerosols can undergo volatilization and condensation, aggregation and disaggregation, photochemical reactions, and mixing with other compounds as they are transported downwind leading to heterogeneous structure both chemically and physically. Current studies show that these aerosol mixtures can have strong impacts on human health, ecosystems, global climate, and weather. It is important to understand these complex aerosol mixtures including their chemical make-up, biological implications, and physical properties, as well as their distribution, fate, and transport in the atmosphere. Recent advances in aerosol modeling have opened a wealth of questions pertaining to the relationship of aerosol chemical evolution, new particle formation, compositional influences on cloud microphysics, and radiative balance. Despite these advances, challenges remain with respect to model verification of aerosol distributions and aerosol properties—especially in under-sampled regions of the globe. This session solicits presentations of research studies on naturally occurring aerosols; e.g., mineral dust, wildfire smoke, sea salt, pollen, and biogenic particles, with a focus on multidisciplinary efforts that investigate their emissions strength, source properties, physical complexity and mixtures, chemical transformations, and transport. Many of these aerosols are directly emitted from other parts of the Earth system, but others can also form or be modified in the atmosphere due to interaction with gaseous emissions and photochemical reactions. This is especially the case with biogenic aerosols, where gas phase volatile organic compounds are emitted that may serve as precursors to secondary organic aerosol formation. Presentations that discuss the novel advances in measurement, modeling and analysis of naturally occurring aerosols including the characterization of the composition of aerosol mixtures, quantifying emission strength, understanding transport and photochemical evolution, and estimating their weather, climate, ecological, or health & safety implications are also invited. Through this session, we hope to catalyze discussions on the chemistry, physics, and biology of aerosols from emissions to impacts.

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