Biogeochemical controls on the sources and chemical composition of Southern Ocean marine aerosols
Natural aerosols impact climate in multiple ways, and are one of the largest sources of uncertainty in our understanding of current and future climate change. Similarly, the lack of information on the concentration and response of aerosols in the preindustrial atmosphere makes it difficult to understand the climatic impact of anthropogenic aerosols, particularly the impact on clouds. The vast and remote Southern Ocean is one of the few places where marine aerosols, the largest component of natural aerosols, can be investigated away from large anthropogenic sources. This region offers a unique laboratory for investigating the present-day controls on the sources, formation processes, and chemical composition of natural marine aerosols, as well as the composition of the preindustrial atmosphere. Previous work on aerosols in the Southern Ocean has primarily relied on global models, satellite remote sensing, or field work on islands and coastal Antarctica. Here, we propose to leverage South Africa’s technical and geographic advantage to conduct an interdisciplinary investigation of the oceanic and atmospheric controls on marine aerosols during summer and winter cruises on the SA Agulhas II. We aim to measure environmental and biogeochemical parameters in the surface ocean concurrently with the size, chemical form, and isotopic composition of marine aerosols. This project will focus on the nitrogen components of the marine aerosol, including nitrogen containing organic aerosol. The results will improve our understanding of the air-sea biogeochemical flux of aerosol precursors, and the formation of marine aerosols with varying climatic impacts. Ultimately, a greater understanding of the mechanisms connecting the ocean-aerosol-cloud-climate system will be incorporated into the CSIR Variable Resolution Earth Systems Model for evaluating the preindustrial atmosphere and the role of the Southern Ocean in natural climate forcing.