Storm-Driven pCO2 Feedback Weakens the Response of Air-Sea CO2 Fluxes in the Sub-Antarctic Southern Ocean

The sub-seasonal CO2 flux (FCO2) variability across the Southern Ocean is poorly understood due to sparse observations at the required temporal and spatial scales. Twinned surface and profiling gliders experiments were used to investigate how storms influence FCO2 through the air-sea gradient in partial pressure of CO2 (Delta pCO(2)) in the sub-Antarctic zone. Winter-spring storms caused Delta pCO(2) to weaken (by 22-37 mu atm) due to mixing/entrainment and weaker stratification. This weakening in Delta pCO(2) was in phase with the increase in wind stress resulting in a reduction of the storm-driven CO2 uptake by 6%-27%. During summer, stronger stratification explained the weaker sensitivity of Delta pCO(2) to storms, instead temperature changes dominated the Delta pCO(2) variability. These results highlight the importance of observing synoptic-scale variability in Delta pCO(2), the absence of which may propagate significant biases to the mean annual FCO2 estimates from large-scale observing programmes and reconstructions.