Role of Sea Surface Microlayer Properties in Cloud Formation

To date, the relative contribution of primary marine organic matter to subset atmospheric particles that nucleate cloud droplets is highly uncertain. Here, condensation nuclei (CCN) measurements were conducted on aerosolized sea surface microlayer (SML) samples collected from North Atlantic Ocean during NASA Aerosols and Marine Ecosystems Study (NAAMES), κ values predicted for three representative high molecular weight (HMW) components aerosol: 6-glucose, humic acid, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). The pure aerosols varied by only ±0.01 across all organics chosen. For desalted SML samples, calculations assuming an composition entirely RuBisCO provided closest with a mean value 0.53 ± 0.10. These results indicate it salt in which drives formation potential aerosols. While presence material ocean waters may increase aerosol mass due enrichment processes, mixed organic/salt will be slightly weakened or unchanged compared spray aerosol.