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The transfer of gases at the ocean-atmosphere interface impacts weather and climate from local to global scales, with carbon dioxide (CO2) key to marine life and ecosystems, and dimethyl sulfide affecting aerosols and atmospheric processes. However, the bubble-mediated gas transfer, associated with breaking waves has remained poorly constrained. We present a spectral framework for bubble-mediated gas transfer, computed from a mechanistic model for air bubble entrainment at the breaking wave scale combined with a chemical model. Gas transfer is upscaled to the ocean scale by evaluating air entrainment at all wave scales using wave and wave breaking statistics. The obtained CO2 gas transfer velocity reproduces the variability of historical parameterizations and recent field measurements, with very good accuracy. We propose a wind-wave parameterization that collapses all available data, which can be directly implemented in ocean-wave models or used with remote sensing of the ocean surface to infer gas transfer.

Plain Language Summary The transfer of gases at the ocean-atmosphere interface impacts weather and climate from local to global scales. The exchanges of carbon dioxide and oxygen are key to marine life and ecosystems, while transfer of dimethyl sulfide has a strong effect on aerosol composition, affecting atmospheric processes. Yet the bubble-mediated gas transfer, associated with breaking waves has remained poorly constrained. We present a general framework for gas transfer in the open ocean, where air entrainment and the associated bubble-mediated gas transfer are evaluated at all scales. We combine a mechanistic model for air entrainment and bubble statistics at the breaking wave scale with a chemical model for gas transfer by the entrained air bubbles and then upscale the gas exchange using the wave and wave breaking statistics. The obtained gas transfer velocity for CO2 reproduces the variability of historical parameterizations and recent field measurements, with very good accuracy, and we propose a wind-wave parameterization that collapse all available data. The proposed model for gas transfer can be directly implemented in coupled ocean-wave models, or used with remote sensing data of the ocean surface to infer gas transfer, strongly improving predictions of gas exchange at the ocean-atmosphere interface.