A Spectral View of the Seasonality and Size Differences of Marine Aerosol in the North Atlantic

Savannah Lewis1, Georges Saliba1, Lynn M Russell1, Patricia Quinn2, Timothy S Bates3, Kay D Bidle4, Benjamin Diaz5, Kimberly Halsey6, Craig A Carlson7 and Michael Behrenfeld6, (1)University of California San Diego, Scripps Institution of Oceanography, La Jolla, CA, United States, (2)NOAA Pacific Marine Environmental Laboratory, Seattle, Washington, WA, United States, (3)NOAA PMEL, Seattle, United States, (4)Rutgers University, Marine and Coastal Sciences, New Brunswick, United States, (5)Rutgers University New Brunswick, Microbial Biology, New Brunswick, NJ, United States, (6)Oregon State University, Corvallis, OR, United States, (7)University of California Santa Barbara, Marine Science Institute/Department of Ecology, Evolution and Marine Biology, Santa Barbara, CA, United States
The relationship between the ocean ecosystem and aerosol composition is an important but complex question that remains to be unsolved. Four cruises were conducted from November 2015 -March 2018 to investigate this relationship - the North Atlantic Marine and Ecosystem Study (NAAMES). Marine aerosol collected during four NAAMES research cruises conducted from November 2015 - March 2018 showed both seasonal differences in their organic functional group composition and differences among three particle size ranges (sub 1 µm, 0.5 µm, and 0.18 µm). Marine samples were identified as those with 3-day back trajectories over the ocean and low values for continental tracers (ozone and nitrate). Analysis of the sub 0.18 µm composition indicates contributions from long-lived continental particles rather than locally-produced marine particles. During the summer and late spring cruises, the carboxylic acid group fraction accounted for 10% to 60% of organic mass, providing evidence of SOA formation. The winter and early spring cruises had negligible acid contributions and were dominated by hydroxy groups. The averaged campaign spectra for primary marine aerosol generated by Sea Sweep are similar for all four campaigns and dominated by the hydroxyl functional group. Larger spectral differences were evident at specific stations, such as those with high biological activity, in which the hydroxyl peak magnitude changes from day to day.