A Lagrangian perspective on the carbon and oxygen budget of an oceanic eddy

Abstract Quantifying the ocean's ability to sequester atmospheric carbon is essential in a climate change context. Measurements of carbon exported to the mesopelagic seldom balance the carbon demand or the oxygen consumption there, suggesting the potential presence of other mechanisms of carbon export. We deployed a BGC Argo float in a cyclone in the Benguela upwelling system for five months in a quasi Lagrangian way, and estimated carbon export and respiration in the eddy via particle imagery with a UVP6. We found that the full eddy core subduction pump, a novel mechanism of particulate carbon export identified here, contributes to one third of the total exported carbon below 450 m (785±355 tons C/day). Moreover, we can balance the carbon supply, carbon demand, and the oxygen consumption if we extrapolate the observed particle size distribution (0.102-16.4 mm) down to 0.025 mm