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

Abstract

Abstract The sub‐seasonal CO 2 flux (FCO 2 ) 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 FCO 2 through the air‐sea gradient in partial pressure of CO 2 (ΔpCO 2 ) in the sub‐Antarctic zone. Winter‐spring storms caused ΔpCO 2 to weaken (by 22–37 μatm) due to mixing/entrainment and weaker stratification. This weakening in ΔpCO 2 was in phase with the increase in wind stress resulting in a reduction of the storm‐driven CO 2 uptake by 6%–27%. During summer, stronger stratification explained the weaker sensitivity of ΔpCO 2 to storms, instead temperature changes dominated the ΔpCO 2 variability. These results highlight the importance of observing synoptic‐scale variability in ΔpCO 2 , the absence of which may propagate significant biases to the mean annual FCO 2 estimates from large‐scale observing programmes and reconstructions.