Séminaire
The Southern Ocean plays a critical role in the global carbon cycle, yet remains one of the most poorly sampled regions. Studies in recent years have suggested that the Southern Ocean has undergone significant change, showing a reduction in ocean carbon uptake. While atmospheric CO2 primarily enters the ocean via sea-air fluxes, the rate-limiting step of ocean carbon uptake remains the ability of the ocean to move carbon, and sequester it in the ocean interior. The pattern of the transport of carbon and other tracers from the surface ocean into the ocean interior is set by a complex pattern of ventilation and reventilation. Here we present new biogeochemical eddy-resolving ocean simulations (1/10°) to explore the relationship between the surface carbon uptake and the transfer of carbon into the ocean interior. Specifically we explore the role of ocean dynamics and mesoscale circulation in controlling the rate and spatial distribution of carbon uptake in the Southern Ocean. In the time-mean, topography-induced stationary Rossby waves introduce small scale upwelling-downwelling systems. In comparison with low-resolution observations, the Rossby waves reveal different dynamical pathways to the ocean interior, with transfers on the northern and southern sides of the deep mixed later pools. We also present preliminary results from a projection experiment with the biogeochemical eddy-resolving ocean simulations (1/10°). We found a reduction in subduction in the future run, which is mainly caused by a shallowing of the mixed layer depths and a weakening of the lateral induction.