The influence of waves and bubbles on oxygen in the ocean interior

Abstract Bubble-mediated exchange during wave breaking is an essential pathway for oxygen transfer at the ocean–atmosphere interface. Conventional wind-dependent gas transfer velocity formulations generally ignore wave-bubble effects and use local wind speed alone to determine the air–sea gas exchange rate. Here, we quantify the influence of waves and bubbles using a generalised wind-wave-bubble gas transfer formulation that accounts for symmetric (diffusive flux through the unbroken ocean and large bubble surface) and asymmetric (pressurised large and small bubbles that dissolve completely) contributions. We contrast it with a widely used wind-dependent formulation using simulations from a global ocean circulation model over the historical period (1959–2020). Including waves and bubbles reduces the model–observation mismatch with quality-controlled biogeochemical Argo float oxygen concentrations in key mode and deep water mass formation regions by ∼70% to 90% and captures observed episodes of bubble-induced supersaturation. This addresses the systematic oxygen undersaturation bias simulated by the wind-dependent simulation. These surface changes propagate into the interior, raising oxygen concentrations by +2 to +10 µ mol kg −1 across most water mass layers. The wind-wave-bubble formulation also enhances flux variability across timescales, and amplifies the climatological seasonal amplitude of the global air–sea oxygen flux by ∼30% relative to the wind-dependent formulation. These results establish bubbles as a first-order, global-scale control on ocean oxygen, resulting in a closer match to observed oxygen saturation and enhancing interior oxygen ventilation.