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A model of gas transfer across air-water interfaces with capillary waves


  • Michel Coantic


The transfer of weakly soluble gases between the atmosphere and seas or lakes is controlled by liquid-phase molecular and turbulent diffusion mechanisms, which essentially depend on wind velocity and gas Schmidt number. A distinct change in regime is observed around 2–3 m s−1, when capillary waves appear, which present models cannot explain. We suggest relating turbulent diffusivity with (1) possible motions close to a “free” liquid-gas interface, (2) mean current distribution in that region, and (3) capillary wave spectra. Resulting transfer velocities explain laboratory and field data at low and moderate wind speeds.

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