Multi-Year Seasonal Trends between Sea Ice, Chlorophyll Concentration, and Clean Marine Aerosol Optical Depth in the Bellingshausen Sea

Biogenic aerosols, formed through either atmospheric oxidation of precursors such as dimethylsulfide (DMS), organohalogens, and other organic compounds, or through direct injection into the atmosphere, have the potential to shape the regional and global climate. Although the formation of secondary organic aerosols (SOA) from volatile organic compounds (VOCs) released by terrestrial biota has been well-explored, despite considerable effort major questions remain in our understanding of aerosol formation from marine biogenic emissions, particularly in polar regions. To determine how sea ice and chlorophyll-a (CHL) concentration are associated with marine aerosol formation we undertook a multi-year satellite remote-sensing analysis in the Bellingshausen Sea for the period (2006-2018). We developed seasonal climatologies and time-series of sea ice, CHL, and layer-integrated clean marine optical depth (CMOD) using satellite-derived data products from passive microwave remote sensing instruments, Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua, and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), respectively. We identified strong seasonality, with CMOD and particulate color ratio (PCR) increasing in late spring until early fall, synchronous with a decrease in sea ice concentration and increase in CHL. Inter-annual variation in the strength of the CMOD and PCR increase appear tied to the extent and duration of the decrease in sea ice concentration and increase in CHL concentration. This is consistent with the hypothesis that the production of biogenically derived marine aerosol is seasonal, with the peak in biogenic aerosols concurrent with the phytoplankton growth season from late spring to early fall.