Air‐sea gas transfer: Its dependence on wind stress, small‐scale roughness, and surface films

laboratory wind wave studies. The slope spectrum of the small-scale waves and the gas transfer velocity are attenuated in the presence of surface films. Observations over largescale gradients of biological productivity and dissolved organic matter show that the reduction in slope and transfer velocity are more clearly correlated with surface film enrichments than with bulk organic matter concentrations. The mean square slope parameterization explains � 89–95% of the observed variance in the data and does not overpredict transfer velocities where films are present. While the specific relationships between gas transfer velocity and wind speed or mean square slope vary slightly with the choice of Schmidt number exponent used to scale the heat transfer velocities to gas transfer velocities, the correlation of heat or gas transfer velocity with mean square slope is consistently better than with wind speed. INDEX TERMS: 0312 Atmospheric Composition and Structure: Air/sea constituent fluxes (3339, 4504); 4504 Oceanography: Physical: Air/sea interactions (0312); 4506 Oceanography: Physical: Capillary waves; 4820 Oceanography: Biological and Chemical: Gases; 4806 Oceanography: Biological and Chemical: Carbon cycling; KEYWORDS: air-sea gas transfer, small-scale waves, surface films