Chair: Kumiko Azetsu-Scott

Clothilde Langlais ^(1)*, Andrew Lenton ⁽¹⁾, Richard Matear ⁽¹⁾, Steve Rintoul ^(1,2)

¹ CSIRO O&A, Hobart, TAS, 7000, Australia
² ACE CRC, Hobart, TAS, 7000, Australia

The Southern Ocean plays a critical role in the global Carbon (C) cycle, yet remains one of the most poorly sampled regions. Studies have suggested that the C sink in the Southern Ocean has undergone significant decadal variations due to changes in ocean circulation. Reduction in ocean C uptake has been attributed to enhanced upwelling of C rich deep water, driven by the intensification and poleward shift of the westerly winds. More recently, strengthening in the ocean C uptake has been related to a tendency towards more zonal winds.

Here we investigate the impact of the intensification and shift of the westerlies on C sequestration in the Southern Ocean using a new biogeochemical eddy-resolving ocean simulations (1/10°). We use historical (1992-2014) and future eddy-resolving experiments (2006-2100) to explore the role of ocean dynamics in controlling the variability and trends in natural and anthropogenic C uptake in the Southern Ocean. As the rate-limiting step of ocean C uptake remains the ability of the ocean to move C in and out of the ocean interior, we assess C subduction through the winter mixed layer alongside air-sea fluxes.