Influence of Wave-Induced Variability on Ocean Carbon Uptake

Abstract

High-frequency wind and wave variability influence air-sea gas fluxes by modulating the gas transfer velocity at the interface. Traditional gas transfer velocity formulations scale solely with wind speed and neglect wave effects, including wave breaking and bubble-mediated transfer. In this study, we quantify the influence of wave effects on the air-sea ${\text{CO}}_2$ flux and ocean carbon storage using a wind-wave-bubble gas transfer velocity formulation in an ocean general circulation model (MOM6-COBALTv2). Wave effects introduce strong variability in global air-sea ${\text{CO}}_2$ fluxes at high-frequency and seasonal timescales (+15–40%). Compared to a traditional wind-dependent formulation, local ${\text{CO}}_2$ fluxes can be modified by 2–20 mmol $m^{-2}$ ${\text{day}}^{-1}$ (i.e., 20–50% flux difference), with the largest differences occurring during storms. The wind-wave-bubble formulation yields a modest global increase in ocean carbon storage (+0.07 PgC ${\text{yr}}^{-1}$, $\sim$3%) due to regional and seasonal compensations, as well as the p${\text{CO}}_2$ feedback that limits the flux response to a faster exchange velocity. Yet, wave effects lead to an enhancement of carbon storage within the ocean interior, with the largest gain in mode and intermediate waters and a wave-induced hemispheric asymmetry in carbon storage. Notably, the southern hemisphere, where wave activity is consistently high, gains more carbon than the more sheltered northern hemisphere. These results highlight the need to account for wave-induced variability to capture local and seasonal carbon dynamics, which are essential, for instance, to high-frequency in situ observational deployments and regional marine carbon dioxide removal assessment efforts.