The sea surface microlayer plays an important role in air-sea interactions. The boundary conditions set by this interfacial region have a significant impact on many air-sea processes of interest to ocean-atmosphere modelers, including the exchange of heat, mass and momentum. In particular, surfactant films are believed to be a significant factor in modulating physical transfer processes; accumulation of these materials causes variations in surface roughness and near surface turbulence via the Marangoni effect and have a strong effect on gas exchange.
During two cruises sponsored under the NSF CoOP Gas Exchange initiative, surface film enrichments were measured concurrently with wind stress, small scale waves and surface turbulence in order to assess the relationships between microlayer surfactant enrichments, atmospheric forcing and sea surface roughness. A coupled surface microlayer skimmer-fluorometry package was deployed on the research platform LADAS to compare CDOM (chromophoric dissolved organic matter) fluorescence in the surface microlayer (upper 50 microns) with that of the subsurface water. Large spatial variations in microlayer fluorescence and surface enrichments were observed. The correspondence between observed CDOM enrichment and suppression of both turbulence dissipation and wave degree of saturation will be discussed along with implications for air-sea gas transfer.