Oceanic convective mixing and the impact on air-sea gas transfer velocity

Combination of surface water cooling and a deep ocean mixed layer generates convective eddies scaling with the depth of a mixed layer that enhances the efficiency of the air-sea transfer of CO2 (and possibly other gases). This enhancement is explained by the convective eddies disturbing the molecular diffusion layer and inducing increased turbulent mixing in the water. The enhancement can be introduced into existing formulations for calculating the air-sea exchange of gases by using an additional resistance, due to large-scale convection acting in parallel with other processes. The additional resistance is expressed here as 1/r(wc) = gamma root w(*)/u(*w), where w(*)/u(*w) characterizes the relative role of surface shear and buoyancy forces. Citation: Rutgersson, A., A. Smedman, and E. Sahlee (2011), Oceanic convective mixing and the impact on air-sea gas transfer velocity, Geophys. Res. Lett., 38, L02602, doi:10.1029/2010GL045581.