Abstract

The Southern Ocean plays an outsized role in the global overturning circulation and climate system by transporting mass, heat, and tracers between basins, as well as between the surface and abyssal oceans. Consequently, the Southern Ocean accounts for a disproportionately large percentage of the total oceanic carbon uptake. Historically, studying the Southern Ocean has been limited by the paucity of observational data from this remote environment. However, recent advances in autonomous float technology have provided unprecedented spatial and temporal coverage of subsurface biogeochemical (BGC) measurements in the region. In this talk, I will discuss two studies that leverage BGC Argo data to investigate the Southern Ocean carbon cycle. The first study examines zonal asymmetry in air-sea carbon fluxes. We show that carbon outgassing occurs preferentially in the Indo-Pacific sector of the Southern Ocean due to regional differences in the mixed-layer entrainment of upwelled carbon-rich deep water. The second study characterizes meridional variations in the phasing of the pCO₂ seasonal cycle and links these to changes in the annual range of sea surface temperature, which in turn is closely related to the mixed-layer depth distribution. Together, these studies illustrate both the advantages and challenges of using float data to investigate carbon system parameters. Understanding these pros and cons is necessary to effectively use the data and integrate it into the larger global ocean observing system