The effects of near-surface turbulence on CO2 flux at the ocean-atmosphere boundary

Ocean alkalinity enhancement (OAE) seeks to store carbon in the ocean as bicarbonate or carbonate ions and thus accelerates CO₂ uptake from the atmosphere. Near-surface ocean turbulence is an important driver of CO₂ uptake by the ocean as it affects the rate at which air-sea gas exchange occurs. Turbulent mixing can also cause high alkalinity water to sink out of the mixed layer, where it will no longer be in contact with the atmosphere. In this presentation we will show the results of high resolution numerical simulations in which alkalinity and dissolved inorganic carbon are advected in a turbulent mixed layer. By coupling the physics to a simple carbonate system solver, we evaluate the potential impact of surface turbulence on CO₂ flux into the ocean. We explore the impact of ocean surface processes on the evolution and downwards diffusion of a surface alkalinity addition as influenced by different wind, temperature and precipitation conditions. The CO₂ flux is computed according to both an empirical and a physically derived parameterization, and an estimate of the sensitivity of the total CO₂ flux to the choice of parameterization is presented.