The Disproportionate Role of Ocean Topography on the Upwelling of Carbon
in the Southern Ocean
Abstract
The physical circulation of the Southern Ocean sets the surface
concentration and thus air-sea exchange of CO2. However, we have a
limited understanding of the three-dimensional circulation that brings
deep carbon-rich waters to the surface. Here, we introduce and analyze a
novel high-resolution ocean model simulation with active biogeochemistry
and online Lagrangian particle tracking. We focus our attention on a
subset of particles with high dissolved inorganic carbon (DIC) that
originate below 1000 m and eventually upwell into the surface mixed
layer. We find that 71% of the DIC-enriched water upwelling across 1000
m is concentrated near topographic features, which occupy just 33% of
the Antarctic Circumpolar Current. Once particles upwell to the surface
mixed layer, their DIC decorrelates on timescales of
~1.5 months—an order of magnitude longer than their
residence time. Our results show that Southern Ocean bathymetry plays a
key role in delivering carbon-rich waters to the surface.