Storms drive outgassing of CO(2) in the subpolar Southern Ocean

The subpolar Southern Ocean is a critical region where CO(2) outgassing influences the global mean air-sea CO(2) flux (F(CO2)). However, the processes controlling the outgassing remain elusive. We show, using a multi-glider dataset combining F(CO2) and ocean turbulence, that the air-sea gradient of CO(2) (∆pCO(2)) is modulated by synoptic storm-driven ocean variability (20 µatm, 1–10 days) through two processes. Ekman transport explains 60% of the variability, and entrainment drives strong episodic CO(2) outgassing events of 2–4 mol m(−2) yr(−1). Extrapolation across the subpolar Southern Ocean using a process model shows how ocean fronts spatially modulate synoptic variability in ∆pCO(2) (6 µatm(2) average) and how spatial variations in stratification influence synoptic entrainment of deeper carbon into the mixed layer (3.5 mol m(−2) yr(−1) average). These results not only constrain aliased-driven uncertainties in F(CO2) but also the effects of synoptic variability on slower seasonal or longer ocean physics-carbon dynamics.