SO-CHIC Toolsee, T., Nicholson, S.-A., & Monteiro, P. M. S. (2024). Storm-driven pCO2 feedback weakens the response of air-sea CO2 fluxes in the sub-Antarctic Southern Ocean. Geophysical Research Letters, 51, e2023GL107804.

April 25, 2024 Toolsee T, Nicholson S-A, Monteiro PMS

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 (ΔpCO₂) in the sub-Antarctic zone. Winter-spring storms caused ΔpCO₂ to weaken (by 22–37 μatm) due to mixing/entrainment and weaker stratification. This weakening in ΔpCO₂ 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 ΔpCO₂ to storms, instead temperature changes dominated the ΔpCO₂ variability. These results highlight the importance of observing synoptic-scale variability in ΔpCO₂, the absence of which may propagate significant biases to the mean annual FCO₂ estimates from large-scale observing programmes and reconstructions.

Publication DOI: https://doi.org/10.1029/2023GL107804