Biologically-active regions of the surface ocean support the production of a range of compounds that influence aerosol particle production, composition and properties in the overlying marine boundary layer. The SOAP (Surface Ocean Aerosol Production) voyage (Law, 2017) in February 2012 examined biotic influences on aerosol production east of New Zealand, by targeting phytoplankton blooms along the biologically productive Sub-Tropical Front. The experiment investigated the relationships between phytoplankton biomass and species distribution, the flux of biogenic gases to the atmosphere and the influence on properties of marine aerosol with a focus on CCN.
We present an overview of campaign findings, and comparison to some other similar studies in the western Pacific region. On the ocean side, we examine the role of the surface microlayer in influencing DMS flux, DMSP cycling, comparison of DMS flux estimates from different techniques. In CCN characterization we examine the relationships between surface ocean and aerosol characteristics. CCN (0.5%) during SOAP had a median concentration of order 200 cm-3 in common with other measurements in the region. Numbers showed some evidence of distant-land influence. Under clean marine conditions, CCN were predominantly derived from coarse mode sea-salt aerosol and more numerous accumulation mode non-sea-salt sulfate. Observations and chemistry-climate modelling with ACCESS-UKCA has suggested there may be a significant contribution by secondary organic aerosol at times.